Vibration of a general and local nature has a certain effect on the human body. This has been proven through multiple studies and experimental tests. Therefore, there are certain allowable vibration levels for industrial or household level. It is very important to take them into account.

The maximum permissible vibration standards at the workplace are those that take into account the vibrations and amplitude of movement of household or industrial equipment for a certain period of work, taking into account the transmission of vibrations to other objects, surfaces and physical bodies located in the room. Sanitary standards introduce regulated sanitary standards for noise and vibration levels. This takes into account the specifics of the equipment and its area of ​​application. Sanitary standards do not regulate vibration changes in machines of independent movement or in transport, since these objects are in motion and do not have a stationary position during operation.

Normalization of vibrations and control over vibration changes

Hygienic standards for noise and vibrations establish permissible vibration standards, which are calculated based on the design features of the element under study, as well as the nature of its application. Notes and uncertainties in vibration measurements should be addressed to the machine manufacturer and designer whose vibration test has not been approved or accepted by the regulatory community. The GOST indicators for the vibration standards of smoke exhausters establish the efficiency, reliability and safety of the equipment.

Sanitary standards for vibration of plunger pumps are needed primarily in order to calculate the safest indicators for the human body, since most of the objects under study are in direct contact with a person and can harm his health if it does not function properly.

The main task of all instruments and sensors for measuring vibration vibrations is to measure the permissible levels of noise and vibration of equipment that is located near workplaces and has direct contact with individuals. Vibration testing should take into account the fact that human contact with a machine in production is systematic and should not contribute to the development of specific occupational diseases or deformations in the body during operation, which may further affect human productivity and performance.

Some of the most notable benefits of testing equipment vibration tolerances include:

• Regular monitoring and systematic measurements of changes in vibration indicators significantly improve the workflow and optimize the labor system. Since any changes in vibration indicators can affect the productivity, performance and physical health of employees.
• Hygienic standards for vibration of pipelines in production allow to draw up a correct picture of working conditions and take measures to improve or optimize them.
• Validation of indicators and the establishment of vibration standards in residential buildings are carried out not only at the production level, but also in the domestic sphere. Knowing the level of vibrations allows you to more competently approach the arrangement of home life, as well as protect yourself from the possible influence of vibrations on the body.
• Local and global checks of vibration standards at enterprises allow you to draw up an overall picture of the sanitary working conditions in a particular area, take measures to improve equipment or modernize work facilities.

What do the regulations reflect?

Based on the results of vibration checks and calculations, the sanitary group provides regulatory documentation and a complete schedule of measurements and vibration indicators of equipment in production or in the household sector. The regulatory package of documents contains the following information:

1) Complete information on the frequency analysis of equipment vibrations, taking into account the peculiarities of their design, operation and placement in a certain area on the inspected area. All measurements and indicators must be based on the regulatory framework and not exceed the permissible vibration level.
2) Integral assessment of the vibration frequency of the tested object, taking into account the characteristics of the test, the equipment used, as well as the nature of the surfaces of the tested equipment and the peculiarities of its use.
3) The maximum permissible vibration doses in the inspected area, taking into account the permissible limits and norms of the sanitary group.

Standard indicators provide data on the maximum permissible limits of vibration velocity and vibration acceleration of the tested equipment or machinery. This takes into account the specifics of its functioning and interaction with individuals.

Based on the results of measurements of vibration indicators, an equivalent indicator of vibration produced in a specific place is calculated and its ratio with the regulated framework of permissible vibrations for the human body at a specific place of work.

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Why and how is the measurement of the permissible vibration dose in production carried out?

The vibration dose is determined by calculating the square of the effect of vibration on the body for a certain period of operation of the investigated element. This counting method allows the most efficient calculation of the allowable vibration range in the workplace. A qualified vibration test of a modern type is capable of analyzing equipment in a remote version at workplaces where the work schedule is not standardized, and a stationary test of the old type is not able to give adequate results and identify errors.

Technical documentation and a regulated framework that establish the basis for testing and the norms for the use of one or another equipment in production should take into account the length of the working day, as well as the peculiarities of the functioning of the objects being checked. Upon completion of the check, the customer is provided with complete documentation on the studies carried out and data on the vibration field of the equipment in the checked area.

The norms of vibration indicators of hand-held equipment are regulated by GOST 17770-72. The main verified indicators of this type of equipment are:

• indicators of vibration and vibration frequencies in the zones of machines that are in direct contact with human hands;
• the force that an employee applies when clicking on a certain area of ​​the checked object in the process of work;
• the total weight of the machine and its individual parts, taking into account the specifics of the manual work of a person with this equipment.

In the process of checking manual machines, attention is paid to the ratio of the mass of the machine and the force of pressing a person on the corresponding area during operation. When checking pneumatic drives, they check the amount of effort that a person puts in the process of working with the equipment.

The force that a person applies when pressing on individual parts of a manual machine in the process of work is also a regulated and standardized indicator that determines the quality and efficiency of labor. This force should not exceed 200N. In this case, the total weight of the tested machine, taking into account the efforts applied by a person when working with it, should not exceed 100N.

It is also important to note that when checking vibration indicators, the heating temperature of the tested equipment during operation is taken into account. The contact surface that comes into contact with human hands should not have a thermal conductivity higher than 0.5 W.

Why do I need a hardware check?

Exceeding the regulated limits of thermal conductivity and vibrations can be detrimental not only for the machine itself (with strong vibrations, parts break, contacts overheat, individual machine parts fail), but also for a person who is in constant contact with equipment during working hours. Vibrations can have a destructive effect on the human body, contribute to the development and occupational diseases.

The EcoTestExpress laboratory offers a comprehensive vibration test of equipment or household appliances, which will allow you to extend the life of the equipment and maintain health. We use only modern and high-precision equipment, which allows us to check all investigated elements as soon as possible. Based on the results of the check, the customer is provided with a complete picture of the production process and the functioning of its individual elements. All calculations and data are recorded in the regulatory journal. It is also later transferred to the hands of the customer for further analysis and making changes to the work or household process.

You can leave a request for an assessment of the vibration level using the form below.

Vibration measurement points for assessing the state of machines and mechanisms are selected on bearing housings or other structural elements that respond to dynamic forces to the maximum extent and characterize the general vibration state of the machines.

GOST R ISO 10816-1-97 regulates vibration measurements of bearing housings in three mutually perpendicular directions passing through the axis of rotation: vertical, horizontal and axial (a). The measurement of the overall vibration level in the vertical direction is carried out at the highest point of the housing (b). The horizontal and axial components are measured at the level of the bearing cap connector or the horizontal plane of the axis of rotation (c, d). Measurements carried out on protective casings and metal structures do not allow determining the technical condition of the mechanism due to the nonlinearity of the properties of these elements.

(a)	(b)
(v)	(G)

a) on electric machines; b) in the vertical direction; c, d) on the bearing housing

The distance from the sensor installation site to the bearing should be as short as possible, without contact surfaces of various parts in the path of vibration propagation. The place of installation of the sensors must be sufficiently rigid (do not install the sensors on a thin-walled case or casing). Use the same measurement points and directions when performing condition monitoring. The increase in the reliability of the measurement results is facilitated by the use at characteristic points of devices for quick fixation of the sensors in certain directions.

Mounting of vibration sensors is regulated by GOST R ISO 5348-99 and the recommendations of the sensor manufacturers. To mount the transducers, the surface on which it is attached must be free of paint and dirt, and when measuring vibration in the high-frequency range - from paint and varnish coatings. The test points at which vibration measurements are taken are designed to ensure repeatability during sensor installation. The place of measurement is marked with paint, punching, installation of intermediate elements.

The mass of the transducer should be less than the mass of the object by more than 10 times. In a magnetic holder, for fixing the sensor, magnets with a holding force of 50 ... 70 N are used; to shift 15 ... 20 N. Not fixed transducer is detached from the surface at acceleration over 1g.

Shock impulses are measured directly at the bearing housing. With free access to the bearing housing, measurements are taken with a sensor (indicator probe) at the test points indicated on. The arrows indicate the direction of the sensor location when measuring shock pulses.

1 - indicator probe of the device; 2 - bearing housing; 3 - propagation of stress waves; 4 - rolling bearing; 5 - area of ​​measurement of shock impulses

Before measuring shock impulses, it is necessary to study the design drawing of the mechanism and make sure that the measurement points are selected correctly, based on the conditions for the propagation of shock impulses. The surface at the measurement site must be flat. Thick layers of paint, dirt, scale must be removed. The sensor is installed in the area of ​​the emission window at an angle of 90 0 to the bearing housing, the permissible deflection angle is not more than 5 0. The force of pressing the stylus to the surface of the control point must be constant.

Selecting a frequency range and vibration measurement parameters

In mechanical systems, the frequency of the disturbing force coincides with the frequency of the response of the system to this force. This allows the source of the vibration to be identified. The search for possible damage is carried out at predetermined frequencies of mechanical vibrations. Most of the damages are rigidly related to the rotor speed of the mechanism. In addition, informative frequencies can be associated with the frequencies of the working process, the frequencies of the elements of the mechanism and the resonant frequencies of the parts.

• the lower frequency range should include 1/3… 1/4 of the turnover frequency;
• the upper frequency range should include the 3rd harmonic of the informative frequency of the controlled element, for example, a gearing;
• the resonant frequencies of the parts must be within the selected frequency range.

Analysis of the overall vibration level

The first step in diagnosing mechanical equipment usually involves measuring the overall vibration level. To assess the technical condition, the rms value (RMS) of the vibration velocity is measured in the frequency range of 10 ... 1000 Hz (for a speed of less than 600 rpm, the range of 2 ... 400 Hz is used). To assess the condition of rolling bearings, vibration acceleration parameters (peak and RMS) are measured in the frequency range of 10 ... 5000 Hz. Low-frequency vibrations freely spread over the metal structures of the mechanism. High-frequency vibrations quickly attenuate with distance from the source of vibrations, which makes it possible to localize the site of damage. Measurement at an infinite number of points of the mechanism is limited to measurements at control points (bearing units) in three mutually perpendicular directions: vertical, horizontal and axial ().

The measurement results are presented in tabular form () for subsequent analysis, which includes several levels.

Table 7 - Values ​​of vibration parameters for control points of a turbocharger

Measuring point	RMS value of vibration velocity (mm / s), for measurement directions, frequency range 10 ... 1000 Hz			Vibration acceleration asks / apik, m / s 2, frequency range 10 ... 5000 Hz
	vertical	horizontal	axial
1	1,8	1,7	0,4	4,9/18,9
2	2,5	2,5	0,5	5,0/19,2
3	3,3	4,0	1,8	39,9/190,2
4	2,4	3,4	1,5	62,8/238,5

First level of analysis- the assessment of the technical condition is carried out according to the maximum value of the vibration velocity recorded at the control points. The permissible level is determined from the standard range of values ​​according to GOST ISO 10816-1-97 (0.28; 0.45; 0.71; 1.12; 1.8; 2.8; 4.5; 7.1; 11, 2; 18.0; 28.0; 45.0). The increase in values ​​in this sequence is 1.6 on average. This series is based on the statement that a 2-fold increase in vibration does not lead to a change in the technical condition. The standard assumes that an increase in values ​​by two levels leads to a change in technical condition (1.6 2 = 2.56). The next statement is that a 10-fold increase in vibration leads to a change in the technical condition from good to emergency. The vibration ratio at idle and under load should not exceed 10 times.

To determine the permissible value, the minimum value of the vibration velocity recorded in the idle mode is used. Let us assume that during the preliminary examination at idle speed the minimum value of vibration velocity of 0.8 mm / s was obtained. Of course, in this case, the axioms of a working state must be observed. It is desirable to define boundaries of states for equipment being put into operation. Taking the nearest higher value from the standard range of 1.12 mm / s as the border of good condition, we have the following estimated values ​​when working under load: 1.12 ... 2.8 mm / s - operation without time limits; 2.8 ... 7.1 mm / s - operation in a limited period of time; over 7.1 mm / s - damage to the mechanism is possible when operating under load.

Long-term operation of the mechanism is possible when the vibration velocity is less than 4.5 mm / s, recorded during the operation of the mechanism under load at the rated speed of the drive motor.

To assess the condition of rolling bearings at a rotation speed of up to 3000 rpm, it is recommended to use the following ratios of the peak and root-mean-square (RMS) values ​​of vibration acceleration in the frequency range of 10 ... 5000 Hz: 1) good condition - the peak value does not exceed 10.0 m / s 2; 2) satisfactory condition - RMS does not exceed 10.0 m / s 2; 3) a bad condition occurs when 10.0 m / s 2 RMS is exceeded; 4) if the peak value exceeds 100.0 m / s 2 - the state becomes emergency.

Second level of analysis- localization of points with maximum vibration. In vibrometry, the thesis is accepted that the lower the values ​​of the vibration parameters, the better the technical condition of the mechanism. No more than 5% of possible damage is due to damage at low vibration levels. In general, large values ​​of the parameters indicate a greater impact of destructive forces and allow localizing the place of damage. There are the following options for increasing (more than 20%) vibration:

1) an increase in vibration throughout the mechanism is most often associated with damage to the base - frame or foundation;
2) a simultaneous increase in vibration at points 1 and 2 or 3 and 4 () indicates damage associated with the rotor of this mechanism - unbalance, bending;
3) increased vibration at points 2 and 3 () is a sign of damage, loss of compensating capabilities of the connecting element - coupling;
4) an increase in vibration at local points indicates damage to the bearing assembly.

Third level of analysis- preliminary diagnosis of possible damage. The direction of the higher vibration value at the control point with higher values ​​most accurately determines the nature of the damage. In this case, the following rules and axioms are used:

1) the values ​​of vibration velocity in the axial direction should be minimal for rotor mechanisms, a possible reason for the increase in vibration velocity in the axial direction is rotor bending, shaft misalignment;
2) the values ​​of vibration velocity in the horizontal direction should be maximum and usually exceed by 20% the value in the vertical direction;
3) an increase in vibration velocity in the vertical direction is a sign of increased compliance of the mechanism base, weakening of threaded connections;
4) a simultaneous increase in vibration velocity in the vertical and horizontal directions indicates an imbalance in the rotor;
5) an increase in vibration velocity in one of the directions - weakening of threaded connections, cracks in the elements of the body or the foundation of the mechanism.

When measuring vibration acceleration, measurements in the radial direction - vertical and horizontal are sufficient. It is desirable to carry out measurements in the area of ​​the emission window - the zone of propagation of mechanical vibrations from the source of damage. The emission window is stationary under local load and rotates if the load is of a circulating nature. An increased value of vibration acceleration most often occurs when rolling bearings are damaged.

Vibration measurements are carried out for each bearing unit, therefore the graph of cause-effect relationships () shows the relationship between the increase in vibration in a certain direction and possible damage to the bearings.

When measuring the general level of vibration, it is recommended to measure the vibration velocity along the contour of the frame, bearing support in the longitudinal or cross section (). The values ​​of the vibration ratio of the support and the foundation that determine the state of the threaded connections and the foundation:

• about 2.0 is good;
• 1.4 ... 1.7 - unstable foundation;
• 2.5 ... 3.0 - loosening of threaded fasteners.

Vibration velocity in the vertical direction on the foundation should not exceed 1.0 mm / s.

Shock Pulse Analysis

The purpose of the shock pulse method is to determine the condition of rolling bearings and the quality of the lubricant. In some cases, shock pulse meters can be used to locate air or gas leaks in pipeline fittings.

The shock pulse method was first developed by SPM Instrument and is based on the measurement and registration of mechanical shock waves caused by the collision of two bodies. Acceleration of material particles at the point of impact causes a compression wave in the form of ultrasonic vibrations propagating in all directions. The acceleration of material particles in the initial phase of impact depends only on the collision velocity and does not depend on the ratio of the body sizes.

To measure shock pulses, a piezoelectric sensor is used, which is not affected by vibration in the low and medium frequency range. The sensor is mechanically and electrically tuned to a frequency of 28 ... 32 kHz. The frontal wave caused by mechanical shock excites damped oscillations in the piezoelectric sensor.

The peak value of the amplitude of this damped oscillation is directly proportional to the impact velocity. A damped transient has a constant damping value for a given state. Changing and analyzing the damped transient process allows assessing the degree of damage and condition of the rolling bearing ().

Causes of increased shock impulses

1. Contamination of the bearing grease during installation, during storage, during operation.
2. Deterioration of the performance properties of the lubricant during operation leading to the inappropriateness of the applied lubricant to the operating conditions of the bearing.
3. Vibration of the mechanism, which creates an increased load on the bearing. Shock pulses are unresponsive to vibration, reflecting deteriorating bearing conditions.
4. Deviation of the geometry of the bearing parts from the specified one, as a result of unsatisfactory mounting of the bearing.
5. Poor shaft alignment.
6. Increased bearing clearance.
7. Loose bearing seating.
8. Shock impacts on the bearing resulting from the operation of the gearing, collisions of parts.
9. Malfunctions of the electromagnetic nature of electrical machines.
10. Cavitation of the pumped medium in the pump, in which shock waves are directly generated in the pumped medium as a result of the collapse of gas caverns.
11. Vibration of connected pipelines or fittings due to unstable flow of the pumped medium.
12. Bearing damage.

Monitoring the condition of rolling bearings using the shock pulse method

There are always irregularities on the surface of the bearing raceways. During the operation of the bearing, mechanical shocks and shock impulses occur. The value of the shock impulses depends on the condition, the rolling surfaces and the peripheral speed. The shock impulses generated by the rolling bearing increase 1000 times from the start of operation to the moment before the replacement. Tests have shown that even a new and lubricated bearing generates shock impulses.

A logarithmic scale is used to measure such large quantities. An increase in the vibration level by 6 dB corresponds to an increase of 2.0 times; by 8.7 dB - an increase of 2.72 times; by 10 dB - an increase of 3.16 times; by 20 dB - an increase of 10 times; by 40 dB - an increase of 100 times; by 60 dB - an increase of 1000 times.

Tests have shown that even a new and lubricated bearing generates shock impulses. The value of this kickoff is expressed as dBi (dBi- initial level). As the bearing wears out, the value increases dBa(the value of the total shock impulse).

Normalized value dBn for a bearing can be expressed as

dBn = dBa - dBi.

The relationship between dBn and bearing life.

Scale dBn divided into three zones (bearing condition categories): dBn< 20 дБ ‑ хорошее состояние; dBn= 20 ... 40 dB - satisfactory condition; dBn> 40 dB - unsatisfactory condition.

Determination of bearing condition

The technical condition of the bearing is determined by the level and ratio of the measured values dBn and dBi. dBn – the maximum value of the normalized signal. dBi- the threshold value of the normalized signal - the background of the bearing. The value of the normalized signal is determined by the diameter and speed of the controlled bearing. These data are entered into the device before measurements are taken.

During bearing operation, peak shocks differ not only in amplitude but also in frequency. Examples of assessing the condition of a bearing and operating conditions (mounting, seating, alignment, lubrication) based on the ratio of the shock amplitude and frequency (the number of blows per minute) are given.

1. In a good bearing, shocks occur mainly from the rolling of the balls over the unevenness of the bearing treadmill and create a normal background level with a low value of the shock amplitude ( dBi< 10), на котором имеются случайные удары с амплитудой dBn< 20 дБ.
2. When damage occurs on the treadmill or rolling elements against the general background, peak values ​​of shocks with a large amplitude appear dBn> 40 dB. The blows occur randomly. Background values ​​lie within dBi< 20 дБ. При сильном повреждении подшипника возможно увеличение фона. Как правило, наблюдается большая разница dBn and dBi.
3. In the absence of lubrication, too tight or weak bearing fit, the background of the bearing increases ( dBi> 10), even if the bearing is not damaged on the treadmills. The amplitude of the peak shocks and the background are relatively close ( dBn= 30 dB, dBi= 20 dB).
4. During pump cavitation, background levels are high in amplitude. The measurement is carried out at the pump casing. It should be borne in mind that curved surfaces dampen shock impulses from cavitation. The difference between the peak values ​​and the background is very small (for example, dBn= 38dB, dBi= 30 dB).
5. Mechanical contact near the bearing between the rotating and stationary parts of the mechanism causes rhythmic (repetitive) shock peaks.
6. If a bearing is subjected to shock loading, such as from a piston stroke in a compressor, the shock impulses will be repetitive in relation to the operating cycle of the machine, so the overall background ( dBi) and peak amplitudes ( dBn) of the bearing itself can be easily identified.

Questions for self-control

1. Where should the vibration test points be located?
2. What is the standard governing vibration measurements?
3. Where should vibration test points not be located?
4. What are the requirements for measuring shock pulses?
5. What are the requirements for choosing a frequency range and vibration measurement parameters?

Noise worsens working conditions and has a harmful effect on the human body. With prolonged exposure to noise on the body, undesirable phenomena occur: visual acuity and hearing decrease, blood pressure rises, and attention decreases. A strong continuous noise can cause functional changes in the cardiovascular and nervous systems. Requirements for noise levels are established by GOST 12.1.003-83 Noise. General safety requirements (with amendment No. 1), СН 2.2.4 / 2.1.8.562 - 96. Noise at workplaces, in the premises of residential and public buildings and on the territory of residential buildings.

Sound as a physical process, it is a wave motion of an elastic medium. A person feels mechanical vibrations with frequencies from 20 to 20,000 Hz.

Noise is a disorderly combination of sounds of different frequencies and intensities.

The main characteristics of sound are:

vibration frequency (Hz); sound pressure (Pa); sound intensity (W / m2). V sound = 344 m / s.

Sound pressure- the variable component of the air pressure, arising from the oscillations of the sound source, superimposed on the atmospheric pressure.

A quantitative estimate of the sound pressure is estimated by the root-mean-square value.

where T= 30-100 ms.

When sound waves propagate, there is a transfer of sound energy, the magnitude of which is determined by the intensity of the sound.

Sound intensity- the sound power per unit area, transmitted in the direction of propagation of the sound wave.

Sound intensity is related to sound pressure by expression

where P is the root-mean-square sound pressure;

V is the root-mean-square value of the vibrational velocity of particles in a sound wave.

In a free sound field, the sound intensity can be expressed by the formula

where r- the density of the medium, with-sound speed in the environment;

rwith is the acoustic resistance of the medium.

The minimum sound pressure and the minimum intensity of sounds that are barely audible by the human hearing aid are called threshold.

The sensitivity of the human hearing aid is greatest in the range of 2000-5000 Hz. For the reference - sound with a frequency of 1000 Hz. At this frequency, the hearing threshold in intensity is I 0 = 10-12 W / m2, and the corresponding sound pressure p0 = 2 · 10-5 Pa. Pain threshold I max = 10 W / m2. The difference is 1013 times.

It is customary to measure and evaluate the relative levels of sound intensity and sound pressure in relation to threshold values, expressed in logarithmic form.

Intensity level: LI= 10 lg I / I0;

Sound pressure level: Lp= 20 lg P / P0-

The audible range is 0 - 140 dB.

The characteristic of the noise source itself is its sound power R- the total amount of sound energy emitted into the surrounding space per second.

Sound power level of the noise source

LP = 10 lg P / P0,

where R0 - threshold value = 10-12W.

The General Safety Requirements provides for the classification of noise, the permissible noise levels in the workplace, the general requirements for the noise performance of machines and methods for measuring noise.

The total sound pressure level during the simultaneous action of two identical sources with levels L1 and L2 in dB can be determined by the formula

Ltotal = L1 + L,

where L1 - the larger of the two summary equations,

L- correction for the total noise equation.

If N sources are the same, then Ltotal = L1 + 10 lgL.

Noise in which sound energy is distributed over the entire spectrum is called broadband... If you hear a sound of a certain frequency, then the noise is called tonal... Noise perceived as individual impulses (shocks) is called impulse.

Sound power and sound pressure as variable quantities can be represented as the sum of sinusoidal oscillations of different frequencies.

The dependence of the rms values ​​of these components (or their levels) on frequency is called frequency spectrum of noise.

Usually, the frequency spectrum is determined empirically, finding the sound pressure not for each individual frequency, but for the octave (or one-third octave) frequency bands.

Geometric mean octave frequency band f cp is defined as:

and for the octave bands f b / f k = 2,

for one-third octave f b / f k = 1.26.

The frequency spectra of noise are obtained using noise analyzers, which are a set of electrical filters that transmit an electrical sound signal in a certain frequency band (bandwidth).

In terms of time characteristics, noises are subdivided into permanent and fickle.

Fickle there are:

- time fluctuating the sound level of which is continuously changing over time;

- intermittent the sound level of which drops sharply to the background noise level;

- impulse consisting of signals less than 1s.

Noise regulation

To assess noise, the frequency spectrum of the measured sound pressure level, expressed in dB, in octave frequency bands, is used, which is compared with the limiting spectrum, normalized in GOST 12.1.003-83 SSBT. Noise. General safety requirements (as amended No. 1).

For an approximate assessment of the noise environment, it is allowed to use a one-number characteristic - the so-called sound level, dBA, measured without frequency analysis on the A scale of the noise meter, which approximately corresponds to the numerical characteristic of human hearing. The human hearing aid is more sensitive to high-frequency sounds, therefore, the normalized sound pressure values ​​decrease with increasing f. For constant noise, the standardized parameters are - permissible sound pressure levels and sound levels at workplaces (according to GOST 12.1.003-83).

For unstable noise, the standardized parameter is the equivalent sound level LA units in dB on the A scale.

Equivalent sound level is the value of the sound level of constant noise, which within the regulated time interval T = t2 - t1 has the same root-mean-square value of the sound level as the noise in question.

Direct noise levels are measured with special integrating noise meters-dosimeters.

If the noise is tonal or impulsive, then the permissible levels should be taken 5 dBA less than the values ​​specified in GOST.

The classification of means and methods of protection against noise is given in GOST 12.1.029 - 80. Means and methods of protection against noise. Classification.

Noise protection methods are based on:

1. reduction of noise at the source;

2. reducing noise in the path of its propagation from the source;

3. the use of PPE against noise (PPE - personal protective equipment).

Pathway noise reduction techniques: - is achieved by carrying out construction and acoustic measures. Methods of noise reduction along the way of its propagation - casings, screens, soundproof partitions between rooms, sound-absorbing facings, noise mufflers. Acoustic treatment of premises means cladding of a part of the internal surfaces of fences with sound-absorbing materials, as well as placement of piece absorbers in the premises.

The greatest effect is in the zone of reflected sound (60% of the total area). The efficiency is 6-8 dB.

Noise reduction method sound absorption based on the transition of sound vibrations of air particles to heat due to friction losses in the pores of the sound-absorbing material. The more sound energy is absorbed, the less it reflects. Therefore, to reduce noise in the room, it is acoustically processed by applying sound-absorbing materials to the inner surfaces, as well as placing piece sound absorbers in the room.

The efficiency of a sound absorbing device is characterized by the sound absorption coefficient a, which is the ratio of absorbed sound energy E ex. to the falling E pad.,

a= E ex. / E pad.

Sound-absorbing devices are porous, porous-fibrous, membrane, layered, volumetric, etc.

Soundproofing is one of the most effective and common methods of reducing industrial noise along its path.

With the help of soundproof barriers, the noise level can be reduced by 30-40 dB.

The method is based on the reflection of a sound wave incident on a fence. However, the sound wave not only reflects off the fence, but also penetrates through it, which causes the fence to vibrate, which itself becomes a source of noise. The higher the surface area of ​​the fence, the more difficult it is to vibrate it, therefore, the higher its sound insulating ability. Therefore, effective sound insulating materials are metals, concrete, wood, dense plastics, etc.

To assess the soundproofing ability of the fence, the concept of sound permeability was introduced t, which is understood as the ratio of sound energy passed through the fence to that falling on it.

The reciprocal of sound permeability is called sound insulation (dB), it is related to sound permeability by the following formula

R = 10 lg (1/ t) .

Vibration

1. Vibration can cause functional disorders of the nervous and cardiovascular systems, as well as the musculoskeletal system.

In accordance with GOST 24346-80 (STSEV 1926-79) Vibration. Terms and Definitions. vibration is understood as the movement of a point or a mechanical system, at which there is an alternate increase and decrease in time of the values ​​of at least one coordinate.

It is customary to distinguish between general and local vibration. General vibration affects the entire human body through the supporting surfaces - seat, floor; local vibration affects individual parts of the body.

Vibration can be measured using both absolute and relative parameters.

The absolute parameters for measuring vibration are vibration displacement, vibration velocity and vibration acceleration.

The main relative parameter of vibration is the level of vibration velocity, which is determined by the formula

LV = 10 log V2 / V02 = 20 log V / V0,

where V- amplitude of vibration velocity, m / s;

V0 = 5 * 10-8 m / s - the threshold value of vibration velocity.

In frequency (spectral) analysis, the kinematic parameters are normalized: mean square values ​​of vibration velocity V(and their logarithmic levels LV) or vibration acceleration a - for local vibrations in octave frequency bands; for general vibration in octave and 1/3 octave frequency bands.

In accordance with GOST 12.1.012-90 SSBT. Vibration safety. General safety requirements there are the following types of general vibration - three categories:

1- transport vibration;

2- transport and technological vibration;

3- technological vibration.

Process vibration, in turn, is subdivided into four types:

3- at permanent workplaces in production facilities, central control posts, etc.;

3b- at workplaces in service premises on ships;

3v- at workplaces in warehouses, household and other industrial premises;

3d - at workplaces in plant administrations, design bureaus, laboratories, training centers, computer centers, office premises and other premises for mental labor.

General vibration is normalized in active bands with geometric mean frequencies of 1, 2, 4, 8, 16, 32, 63 Hz and in 1/3 octave bands with geometric mean frequencies of 0.8; 1.0; 1.25; 1.6; ... 40; 50; 63; 80 Hz.

Local vibration is normalized in active bands with geometric mean frequencies of 8, 16, 32, 63, 120, 250, 500, 1000 Hz.

Vibration is normalized in the direction of three orthogonal coordinate axes X, Y, Z for general vibration, where Z is the vertical axis, and Y, X are horizontal; and XP, YP, ZP - for local vibration, where XP coincides with the axis of the vibration source, and the ZP axis lies in the plane formed by the XP axis and the direction of force feed or application.

The permissible values ​​of the parameters of transport, transport-technological and technological vibration are given in GOST 12.1.012-90.

At integrated assessment vibration in frequency, the normalized parameter is the corrected value of the controlled parameter V (vibration velocity or vibration acceleration), measured using special filters or calculated using the formulas given in GOST 12.1.012-90.

Dose approach allows you to assess the cumulation of the impact of a factor at work and outside working hours.

When evaluating vibration dose the normalized parameter is equivalent corrected valueVEKV determined by the formula

VEKV =,

where is the dose of vibration, which is calculated by the expression

where V (t) is the instantaneous corrected value of the vibration parameter at the moment of time t, obtained using a correcting filter with a characteristic in accordance with the table given in the standard, t- the time of exposure to vibration per work shift.

Noise and vibration meter VSHV - 001; as well as foreign vibroacoustic kits from Brüel & Kjer (Denmark).

General vibration measurement points are selected at workplaces (or in service work areas), and for self-propelled and transport-technological machines - at work areas and the seats of drivers and personnel. Measurements are carried out in a typical technological mode of operation of the equipment (machine).

The total time of work in contact with hand-held machines that cause vibration should not exceed 2/3 of a shift. At the same time, the duration of a one-time exposure to vibration, including micropauses, which are part of this operation, should not exceed 15-20 minutes.

The total time of work with a vibrating tool is about 8 hours. a working day and a 5-day week should not exceed 30% of the shift working time for an assembly fitter, 22% for an electrician; for the adjuster 15%.

When working with a vibration instrument, the mass of equipment held by hands should not exceed 10 kg, and the pressing force should not exceed 196 N.

The main methods of dealing with vibrations of machinery and equipment are:

Reducing vibration by acting on the source of excitation (by reducing or eliminating the driving forces);

Detuning from the resonance mode by rational choice of mass and stiffness of the oscillating system; (either by changing the mass or rigidity of the system, or at the design stage - a new mode w).

Vibration damping is an increase in the mechanical active impedance of vibrating structural elements by increasing dissipative forces during vibrations with frequencies close to resonance.

Dissipative forces are forces that arise in mechanical systems, the total energy of which (the sum of kinetic and potential energy) decreases during motion, passing into other types of energy.

A dissipative system, for example, is a body moving along the surface of another body in the presence of friction (vibration coating is the viscosity of materials).

Dynamic damping of oscillations - (additional reactive impedances) - connection of systems to the protected object, the reaction of which reduces the vibration range at the points of connection of the system;

Modification of structural elements and building structures (increasing the rigidity of the system - the introduction of stiffeners).

Vibration isolation - this method consists in reducing the transmission of vibrations from the excitation source to the protected object using devices placed between them. (Rubber, spring vibration isolators).

Active vibration protection.

General requirements for PPE against vibration are defined in GOST 12.4.002-97 SSBT. Personal protective equipment for hands from vibration. General technical requirements and GOST 12.4.024 - 76. Special vibration-resistant footwear.

Requirements for lighting production facilities and workplaces. Characteristics of natural and artificial lighting. Illumination standards. The choice of light sources, lamps. Organization of operation of lighting installations.

Correctly designed and executed lighting enables normal production activities.

A person receives about 80% of the total amount of information through the visual channel. The quality of the incoming information largely depends on the lighting: if it is unsatisfactory in quantity or quality, it not only tires the eyesight, but also causes fatigue of the body as a whole. In addition, irrational lighting can cause injuries: poorly lit hazardous areas, blinding light sources and glare from them, harsh shadows impair visibility so much that it causes a complete loss of orientation of workers.

In case of unsatisfactory lighting, in addition, labor productivity decreases and product rejects increase.

Lighting is characterized by quantitative and qualitative indicators.

Quantitative indicators include: luminous flux, luminous intensity, illumination and brightness.

The part of the radiant flux that is perceived by human vision as light is called the luminous flux F and is measured in lumens (lm).

Luminous flux Ф - the flux of radiant energy, assessed by visual sensation, characterizes the power of light radiation.

The unit of luminous flux is lumen (lm) - the luminous flux emitted by a point source with a solid angle of 1 steradian at a luminous intensity of 1 candela.

The luminous flux is defined as a quantity not only physical, but also physiological, since its measurement is based on visual perception.

All light sources, including lighting devices, emit a luminous flux into space unevenly, therefore, the value of the spatial density of the luminous flux is introduced - the luminous intensity I.

The luminous intensity I is defined as the ratio of the luminous flux dF emanating from the source and spreading uniformly within the elementary solid angle to the value of this angle.

Candela (cd) is taken as a unit of luminous intensity.

One candela is the intensity of light emitted from a surface with an area of ​​1/6 · 10 5 m 2 of total radiation (state standard of light) in the perpendicular direction at the solidification temperature of platinum (2046.65 K) at a pressure of 101325 Pa.

Illumination E - the ratio of the luminous flux dF incident on the surface element dS to the area of ​​this element

Lux (lx) is taken as the unit of illumination.

The brightness L of a surface element dS at an angle relative to the normal of this element is the ratio of the luminous flux d2F to the product of the solid angle dΩ, β in which it propagates, the area dS and the cosine of the angle?

L = d2F / (dΩ dS cos θ) = dI / (dS cosθ),

where dI is the intensity of light emitted by the surface dS in the direction θ.

The reflectance characterizes the ability to reflect the light flux incident on it. It is defined as the ratio of the luminous flux reflected from the surface Fotr. to the flow Fpad falling on it ..

The main quality indicators of lighting include the ripple coefficient, the indicator of dazzle and discomfort, and the spectral composition of light.

To assess the conditions of visual work, there are characteristics such as the background, the contrast of the object with the background.

When lighting industrial premises, natural lighting is used, created by the light of the sky, penetrating through the light openings in the external enclosing structures, artificial, carried out by electric lamps and combined, in which insufficient natural lighting is supplemented by artificial lighting.

Natural lighting of the room through the light openings in the outer walls is called lateral, and the lighting of the room through the lanterns, light openings in the walls at the points of difference in the heights of the building is called the upper. The combination of top and side natural lighting is called combined natural lighting.

The quality of natural light is characterized by the coefficient of natural illumination (KEO). It is the ratio of natural illumination created at a certain point of a given plane inside the room by the light of the sky to the value of the external horizontal illumination created by the light of a completely open firmament; expressed as a percentage.

By design, artificial lighting can be of two systems - general and combined. In the general lighting system, the luminaires are placed evenly in the upper area of ​​the room (general uniform illumination) or in relation to the arrangement of the equipment (general localized lighting). In a combined lighting system, local lighting is added to the general lighting, created by lamps that concentrate the luminous flux directly at the workplace.

Local lighting alone is not allowed.

According to their functional purpose, artificial lighting is divided into the following types: working, security, evacuation, security and duty.

Work lighting - lighting that provides standardized lighting conditions (illumination, lighting quality) in rooms and in places where work is performed outside buildings.

Safety lighting - lighting arranged to continue work in the event of an emergency shutdown of the working lighting. This type of lighting should create on work surfaces in industrial premises and on the territories of enterprises that require maintenance when the working lighting is turned off, the lowest illumination in the amount of 5% of the illumination standard for working lighting from general lighting, but not less than 2 lux inside the building and not less than 1 lux for territories of enterprises.

Evacuation lighting should be provided for the evacuation of people from premises in case of emergency shutdown of working lighting in places dangerous for the passage of people. It should provide the lowest illumination on the floor of the main aisles (or on the ground) and on the steps of stairs: indoors - 0.5 lux, and in open areas - 0.2 lux.

Safety lighting and evacuation lighting are called emergency lighting. Exit doors of public premises for public use, in which more than 100 people can stay, as well as exits from production premises without natural light, where more than 50 people can be at the same time or having an area of ​​more than 150 m2, must be marked with signs. Exit signs can be light or non-light, provided that the exit designation is illuminated by emergency lighting luminaires.

Lighting devices for emergency lighting are allowed to be provided lit, turned on simultaneously with the main lighting devices of normal lighting and not lit, automatically turned on when the power supply to normal lighting is cut off.

Security lighting should be provided along the boundaries of areas protected at night. Illumination should be at least 0.5 lux at ground level in the horizontal plane or at a level of 0.5 m from the ground on one side of the vertical plane perpendicular to the border line.

Duty lighting is provided for non-working hours. Its scope, illumination values, uniformity and quality requirements are not standardized.

The main task of lighting in manufacturing is to create the best possible conditions for vision. This task can only be solved by a lighting system that meets certain requirements.

Illumination at the workplace should correspond to the nature of visual work, which is determined by the following parameters:

The smallest size of the object of discrimination (the object under consideration, its separate part or defect);

The characteristic of the background (the surface adjacent directly to the object of discrimination, on which it is viewed); the background is considered light - with a surface reflection coefficient of more than 0.4, average - with a surface reflection coefficient from 0.2 to 0.4, dark - with a surface reflection coefficient of less than 0.2.

The contrast of the object of discrimination with the background K, which is equal to the ratio of the absolute value of the difference between the brightness of the object Lo and the background Lf to the brightness of the background K = | Lo - Lf | / Lf; the contrast is considered large - at K more than 0.5 (the object and background differ sharply in brightness), medium - at K from 0.2 to 0.5, (the object and background differ noticeably in brightness), small - at K less than 0, 2 (subject and background differ slightly in brightness).

It is necessary to ensure a sufficiently uniform distribution of brightness on the working surface, as well as in the surrounding space. If there are surfaces in the field of view that differ significantly from each other in brightness, then when looking from a brightly lit to a dimly lit surface, the eyes are forced to re-adapt, which leads to visual fatigue.

There should be no harsh shadows in the workplace. The presence of sharp shadows creates an uneven distribution of surfaces with different brightness in the field of view, distorts the size and shape of objects of discrimination, as a result, increases fatigue, decreases productivity. Moving shadows are especially harmful and can cause injury.

There should be no direct and reflected glare in the field of view. Glare - increased brightness of luminous surfaces, causing impairment of visual functions (glare), i.e. deterioration of the visibility of objects.

Direct glare is associated with light sources, reflected glare occurs on surfaces with high reflectivity or reflections towards the eye.

The criterion for assessing the blinding effect created by the lighting installation is the indicator of blinding Ro, the value of which is determined by the formula

Po = (S - 1) 1000,

where S is the dazzle factor, equal to the ratio of the threshold brightness differences in the presence and absence of dazzling sources in the field of view.

The criterion for evaluating uncomfortable gloss, causing discomfort with an uneven distribution of brightness in the field of view, is the indicator of discomfort.

The amount of illumination should be constant over time so that eye fatigue does not occur due to readaptation. The characteristic of the relative depth of illumination fluctuations as a result of changes in the luminous flux of light sources with time is the coefficient of illumination ripple Kp.

Kp (%) = 100 (Emax - Emin) / 2Eav,

where Еmax, Emin and Еср are the maximum, minimum and average values ​​of illumination during the period of its fluctuation.

For correct color rendering, you should choose the required spectral composition of light. Correct color rendering is ensured by natural lighting and artificial light sources with a spectral characteristic close to that of the sun.

Requirements for the lighting of premises are established by SNiP 23-05-95 Natural and artificial lighting. For the premises of industrial enterprises, standards have been established for KEO, illumination, permissible combinations of indicators of glare and pulsation coefficient. The values ​​of these norms are determined by the category and sub-category of visual work. A total of eight categories are provided - from I; where the smallest size of the object of discrimination is less than 0.15 mm, up to VI, where it exceeds 5 mm; VII category is set for work with luminous materials and products in hot shops, VIII - for general monitoring of the production process. At distances from the object of discrimination to the eye of the worker of more than 0.5 m, the category of work is set depending on the angular size of the object of discrimination, determined by the ratio of the minimum size of the object of discrimination to the distance from this object to the eyes of the worker. The sub-category of visual work depends on the characteristics of the background and the contrast of the object to be distinguished from the background.

For residential premises, public administrative buildings, standards have been established for KEO, illumination, discomfort indicator and coefficient of illumination ripple. In cases of special architectural and artistic requirements, cylindrical illumination is also regulated. Cylindrical illumination characterizes the saturation of the room with light. It is calculated by the engineering method.

The choice of these norms depends on the category and sub-category of visual work. For such premises, 5 categories of visual work are provided - from A - to D.

Visual work belongs to one of the first three categories (depending on the smallest size of the object of discrimination) if it consists in distinguishing objects with a fixed and non-fixed line of sight. In this case, the sub-category of visual work is determined by the relative duration of visual work with the direction of vision to the working surface (%).

Visual work belongs to the G&D category if it consists in an overview of the surrounding space with a very short, episodic distinction of objects. The G discharge is established at a high saturation of the room with light, and the D discharge - at normal saturation.

The norms of natural light depend on the light climate in which the administrative region is located. The required value of KEO is determined by the formula

KEO = en mN,

Where N is the number of the group of natural light provision, which depends on the implementation of light openings and their orientation on the sides of the horizon;

eн - the value of KEO indicated in the tables of SNiP 23-05-95;

mN - coefficient of light climate.

As a rule, the most economical discharge lamps should be used for illumination of industrial premises and warehouse buildings. The use of incandescent lamps for general lighting is allowed only in case of impossibility or technical and economic inexpediency of using discharge lamps.

For local lighting, in addition to discharge light sources, incandescent lamps, including halogen lamps, should be used. Indoor use of xenon lamps is not permitted.

For local illumination of workplaces, luminaires with opaque reflectors should be used. Local lighting of workplaces, as a rule, should be equipped with dimmers.

In rooms where a stroboscopic effect is possible, it is necessary to turn on neighboring lamps in 3 phases of the supply voltage or turn them on to a network with electronic ballasts.

In the premises of public, residential and auxiliary buildings, if it is impossible or technically and economically inexpedient to use discharge lamps, as well as to ensure architectural and artistic requirements, it is allowed to provide incandescent lamps.

Lighting of stairwells of residential buildings with a height of more than 3 floors should have automatic or remote control, which ensures that part of the lamps or lamps is turned off at night so that the illumination of the stairs is not lower than the evacuation lighting standards.

In large enterprises, there should be a dedicated person in charge of lighting operation (engineer or technician).

The level of illumination at the control points of the production room should be checked after the next cleaning of the lamps and replacing the burned out lamps.

Cleaning of glass skylights should be carried out at least 4 times a year for rooms with significant dust emissions; for lamps - 4-12 times a year, depending on the nature of the dustiness of the production area.

Burnt-out lamps must be replaced promptly. In installations with fluorescent lamps and DRL lamps, it is necessary to monitor the serviceability of switching circuits, as well as ballasts.

Vibration

What is vibration?

Vibration is vibration of solids or particles with a frequency of less than 20 Hz, which is perceived by a person through touch.

Why is prolonged exposure to vibration harmful to humans?

Vibrations in excess of the permissible sanitary standards are harmful to the nervous and cardiovascular systems. Workers exposed to the harmful effects of vibration for a long time develop vibration disease, the main signs of which are neurovascular disorders of the fingers, which manifests itself in increased sensitivity to cooling of the hands (numbness, blue discoloration or pallor), the appearance of pain in the joints of the hands and fingers, and also headaches, fatigue and irritability.

What can be the source of harmful vibrations in agriculture?

The operator working on a tractor or any other agricultural machine can be exposed to the harmful effects of vibrations. Handheld electric or pneumatic tools used in the repair of agricultural machinery can also create vibrations that are harmful to the worker. These are the most common sources of vibration.

What are the maximum permissible sanitary standards for vibration?

The norms limiting vibrations when working with mechanisms and equipment and at the workplace are given in table 8.

Table 8. Vibration limiting norms

frequency Hz	Vibroinstrument		Workplace
		vibrational speed, cm / s	oscillatory speed level, dB	vibrational speed, cm / s
			—	—

At frequencies up to 11 Hz, the following vibrational displacements are standardized for workplaces:

frequency Hz	1	2	3	4	5	6	7	8	9	10	11
Displacement, mm	0,6	0,5	0,4	0,2	0,1	0,08	0,07	0,05	0,045	0,04	0,035

Who gives permission to work with a tool whose vibration exceeds sanitary standards?

The administration of the enterprise must obtain such permission from the local authorities of the sanitary and epidemiological service.

It is forbidden to work with machines, the vibration levels of which are more than 4 times (more than 12 dB) higher than the sanitary standards.

How is vibration measured?

Vibrometers and vibrographs of various models are used to measure vibrations at workplaces. The most widespread noise and vibration meter is ISHV-1. The vibration of the instrument is also measured with sound level meters.

How are the vibration parameters of machines determined?

The vibration parameters of machines are determined according to the data of technical documentation for new machines, and for those in operation - according to actual measurements carried out at least once a year, as well as after repairs for all types of machines, and for manual machines - at least twice a year.

What is the permissible contact time of a person working with a vibrating tool or at a workplace with a machine that does not meet the requirements of sanitary standards?

The contact time of workers in this case depends on the value of exceeding the permissible levels of sanitary standards and corresponds to the following values ​​(Table 9).

Table 9. Permissible contact time of those working with vibration tools that do not meet sanitary standards

Exceeding the permissible levels of vibration velocity in octave frequency bands relative to sanitary standards, dB	Permissible total vibration activity per work shift, min
	manual machines	workplace
Up to 3 (1.41 times)
Up to 6 (2 times)
Up to 9 (2.8 times)
Up to 12 (4 times)

To eliminate the influence of harmful vibrations on the worker, it is necessary to observe the ratio of the duration of exposure to vibration and the performance of other operations not related to it, at least 1: 2. For example, if the sanitary standards for vibration of a manual machine are exceeded up to 9 dB, it is advisable to establish a procedure for operating the machine for 10 minutes with periods of other types of work of 20 minutes each, that is, 10 + 20 + 10 + 20 + 10 + 20 + 10 = 100 minutes. The rest of the working time (480-100 = 380 min) must be carried out work not related to vibration.

What are the requirements for vibrating equipment?

Vibrating equipment includes a power tool, mechanisms, manual controls, fixtures or workpieces, when working with which vibrations occur in excess of 20% of the maximum permissible sapitary standards.

Only equipment, tools, mechanisms or devices that are in good condition, within the limits of permissible wear, should be allowed to operate.

Equipment and machines that generate vibrations, after repair, before commissioning, are checked for compliance with vibration sanitary standards.

It is forbidden to use vibrating equipment in modes other than the passport one, if the resulting vibrations transmitted to the hands of the workers and the pressing forces exceed the sanitary standards.

What are the requirements for the operating personnel of vibrating equipment?

Persons at least 18 years of age who have passed a medical examination, have the appropriate qualifications and have passed the technical minimum according to the rules of safe work are allowed to work with vibrating equipment.

It is forbidden to admit to work associated with exposure to vibration, persons suffering from cardiovascular diseases, active tuberculosis, peptic ulcer disease, autonomic-endocrine disorders, functional disorders of the peripheral and central nervous system, mental illness, diseases of the musculoskeletal system, diseases of the middle and inner ear, chronic liver disease.

When working with vibrating equipment that meets the requirements of sanitary standards, the total time of contact with vibrating surfaces should not exceed 2/3 of the working day. With this mode of work, if other factors of working conditions comply with sanitary standards, the lunch break should be at least 40 minutes and two regulated breaks for active rest, industrial gymnastics and physioprophylactic procedures are established: 20 minutes after 1 ... 2 hours after the start of the shift and 20 ... 30 minutes after 2 hours after the lunch break.

Overtime work with vibrating equipment is prohibited.

Working with vibrating equipment is carried out, as a rule, in heated rooms with an air temperature of at least 16 °, with a humidity of 40 ... 60% and a speed of no more than 0.3 m / s.

When working in a cold season in unheated rooms or in the open air, for periodic heating of workers, heated rooms should be created with an air temperature of 22 ° C at a speed of its movement of no more than 0.3 m / s and a humidity of 40 ... 60%.

At workplaces, local heating is provided. Those working with power tools are provided with personal vibration protection equipment.

All workers engaged in work with vibrating equipment undergo periodic examinations once a year with the participation of doctors: therapist, neuropathologist, otolaryngologist, and, if indicated, other specialists.

Workers who show even the initial signs of vibration sickness are transferred to work that is not associated with exposure to vibration and noise.

For the prevention of vibration sickness, it is recommended to periodically use workers in other operations that are not associated with exposure to vibration. For this purpose, complex teams are being introduced at repair enterprises, where its members alternate with jobs during production processes.

Vibrations are one of the problems of modern megacities. Moreover, their intensity is constantly increasing every year. Why is modern science so actively investigating this problem? Why has vibration measurement become mandatory in many organizations and factories? The fact is that vibration is a phenomenon that causes a number of occupational diseases, which gives doctors reason to raise questions about measures to eliminate it.

Vibration concept

Vibration is a complex oscillatory process that occurs over a wide frequency range. How does it arise? When transferring vibrational energy from a source to a solid. Usually, vibration is understood as having a tangible effect on the human body. This refers to the frequency range from 1.6 to 1000 Hz. Sound and noise are closely related to the concept of vibration. They accompany this phenomenon at high rates of oscillatory motion.

What subject at school studies such a concept as vibration? This is a very important subject. Ensuring labor protection is one of the main problems in Russia, raised to the level of national security.

Sources of occurrence

Mechanical vibrations are phenomena that occur in almost all machine tools, machines and tools that have unbalanced or unbalanced rotating parts that perform reciprocating and shock movements. The list of such equipment includes stamping and forging hammers, pneumatic and electric hammers, as well as fans, compressors, pumping units and drives.

If vibrational movements of mechanical bodies are performed with a frequency in the range of up to 20 Hz, then they are perceived only as vibration. Sound appears at high frequencies. It is vibration with noise. In this case, perception is produced not only by the vestibular apparatus of a person, but also by his hearing organs.

Vibration classification

Oscillatory movements can be transmitted in various ways. So, there is a general vibration. This is an oscillatory process that is transmitted to the human body through various supporting surfaces. General vibration adversely affects the cardiovascular and nervous systems. In addition, it causes pathologies of the digestive tract and organs of movement.

In turn, the following are distinguished from the general vibration:
- transport, arising from the movement of cars on the road;
- transport and technical, the source of which are machines and mechanisms involved in the technological process;
- technical, arising during the operation of stationary equipment or transmitted to the areas where the operating personnel are located, where there are no sources of vibration.

There is also local vibration. These are oscillatory movements transmitted through the hands. If a person encounters such a vibration systematically, then he may develop neuritis with a simultaneous disability.

When examining workplaces, harmonic or sinusoidal vibration is highlighted. These are such oscillatory movements in which the values ​​of their main indicator change according to a sinusoidal law. This vibration is especially common in practice.

Oscillatory movements are also distinguished by their temporal characteristics. So there is a constant vibration. Its parameters in their frequency change no more than twofold during the observation period.

There is also a fickle vibration. It is characterized by a significant change in the main parameters (more than twice).

In the study of which subject, students are given the opportunity to become more familiar with such a phenomenon as vibration? This is BZD. It is taught in high school.

Vibration parameters

The following values ​​are used for characterization:
- amplitude, showing the greatest deviation from the equilibrium position in meters;
- vibration frequency, determined in Hz;
- the number of oscillatory movements per second;
- the speed of vibrations;
- period of fluctuations;
- acceleration of vibrations.

Industrial vibration

Questions about reducing the level of oscillatory movements that negatively affect the human body are especially relevant at the stage of developing a technological process, which is impossible without operating machines, machines, etc. But, nevertheless, industrial vibration is a phenomenon that cannot be avoided in practice. It arises due to the presence of gaps, as well as surface contacts between individual mechanisms and parts. Vibration also occurs when equipment elements are unbalanced. Oscillatory movements often increase many times over due to resonance phenomena.

Vibration monitoring

To control and further reduce the level of vibration in production, special vibration measuring control and signal equipment is used. It allows you to maintain the performance of outdated equipment and increase the service life of new machines and mechanisms.

Everyone knows that the technological process of any industrial enterprise requires the participation of a large number of fans, electrical machines, etc. In order for the equipment not to stand idle, technical services must carry out its timely maintenance or overhaul. This is possible when monitoring the vibration level, which allows timely detection of:
- unbalanced rotor;
- bearing wear;
- gear misalignment and other malfunctions and deviations.

The vibration control equipment installed on the equipment issues warning signals in case of an emergency increase in the vibration amplitude.

Effects of vibration on human health

Oscillatory movements primarily cause pathologies of the nervous system, as well as the tactile, visual and vestibular apparatus. Professional motor vehicle drivers and machinists complain of ailments of the lumbosacral spine. These pathologies are the result of the systematic impact of shock and low-frequency vibration that occurs at their workplace.

Those to whom oscillatory movements of the equipment are transmitted during the technological cycle suffer from pain in the limbs, lower back and stomach, as well as from lack of appetite. They develop insomnia, fatigue and irritability. In general, the picture of the effect of general vibration on a person is expressed in autonomic disorders, accompanied by peripheral disorders in the limbs, a decrease in sensitivity and vascular tone.

Exposure to local oscillatory movements leads to vasospasm of the vessels of the forearms and hand. In this case, the limbs do not receive the required amount of blood. Along with this, local vibration affects bone and muscle tissue, as well as the nerve endings located in them. This leads to a decrease in the sensitivity of the skin, to the deposition of salts in the joints, to deformation and reduced mobility of the fingers. It is worth mentioning that the oscillatory movements performed in the range sharply reduce the tone of the capillaries, and at high frequencies, vasospasm occurs.

Occasionally, a worker has a vibration in his ear. What is this phenomenon? The fact is that the frequency of vibrational movements transmitted from operating equipment is very different. However, in a single enterprise, there is a rather narrow range of such values. This leads to the appearance of this or that type of vibration, as well as the accompanying noise. For example, sounds can have a low, medium and high frequency.

When does vibration occur in the ear? What does this state characterize by itself? The fact is that sometimes the equipment creates oscillatory movements that are on the same level with auditory perception. As a result, the noise is transmitted to the inner ear through the body of the worker and his bones.

In practice, the permissible vibration level is distinguished. These are those values ​​that do not have a negative effect on the human body. These parameters depend on many factors (on the exposure time, the purpose of the room, etc.) and are measured by the vibration amplitude, vibration velocity, vibration acceleration and frequency.

Most Dangerous Vibration Levels

Features of the negative impact of oscillatory movements on the human body are determined by the nature of their distribution with a combination of mass and elastic elements. In a standing person, these are the torso, pelvis and lower spine. In a chair sitting, the upper body and spine are negatively affected.

The effect of vibration on human health is determined by its frequency spectrum. Those manual mechanisms, the oscillatory movements of which are below 35 Hz, contribute to the appearance of negative changes in the joints and the musculoskeletal system.

The most dangerous vibrations are close to human organs. This range is from 6 to 10 Hz. Fluctuations of this frequency also negatively affect psychological health. This frequency could well be the cause of the deaths of many travelers in the Bermuda Triangle. At vibration values ​​from 6 to 10 Hz, people have a feeling of fear and danger. At the same time, sailors strive to leave their ship as soon as possible. Prolonged exposure to vibration can lead to the death of the crew. This phenomenon is dangerous for the functioning of both individual organs and the whole organism. It disrupts the central nervous system and metabolism.

Vibration with a large amplitude is very dangerous. It has a negative effect on bones and joints. With prolonged exposure and high intensity of vibrations, such a vibration provokes the development. This professional pathology, under certain conditions, turns into a cerebral form, which is almost impossible to cure.

Elimination of oscillatory movements

How to avoid vibration in the body? What kind of activities should these be that will help preserve human health? There are two main groups of these methods. The measures of the first of them are designed to reduce vibration directly at the source of its occurrence. Such actions, carried out at the design stage, provide for the use of silent equipment and the correct selection of its operating modes. During the construction and further operation of industrial buildings, these measures relate to measures for the use of technically sound equipment.

The second method to reduce vibration is to eliminate it along the path of propagation. For this, vibration isolation of equipment and air ducts is carried out, vibration isolation platforms are built, workplaces are equipped with special rugs and seats. In addition, vibration in the path of its propagation can be eliminated by performing a whole range of acoustic and architectural planning measures. Among them:
- location of vibration sources at the maximum distance from protected objects;
- Appropriate placement of equipment;
- the use of a vibration-insulated and rigid mounting scheme for the unit, etc.

Time protection

In order to preserve the health of a person working with manual mechanisms or equipment transmitting oscillatory movements to the body, special modes of rest and work are being developed. So, there is a limitation of the time of contact with machines and mechanisms up to 1/3 of a shift. In this case, two or three breaks of 20-30 minutes are necessarily arranged. Moreover, free time from work during the shift is provided for a variety of physiotherapy procedures.

Such work regimes are developed for vibration-hazardous professions and are a kind of preventive measures aimed at preserving human health.

Numerical name vibration

When dealing with different people, each of us behaves in completely different ways. And all this depends on the attitude towards the interlocutor and on the current situation. We despise or respect, hate or love, we listen to their opinion, or we do not care at all.

If a person met on the path of life is restrained and laconic, then this behavior becomes characteristic of us. A merry fellow and a joker, on the contrary, will make you laugh and will certainly cheer you up. How to find out that individuality of a person, which is hidden in the depths of his soul? The vibration of the name will tell you a lot. What is it? Numerological addition of consonants of a name. Using this method, you can determine the nature of relatives and spouses, friends and any person, even without knowing the date when he was born. It is only necessary to know the 9 numerical vibrations corresponding to the name. With their help, you can pick up the key to the human soul and feel like a real magician. No wonder some people say that this is the vibration of my heart. Indeed, with the help of this method, a magical weapon appears in the hands of a person, which will benefit those who know its power of influence and its main meaning.

The letters of each person's name conceal three meanings of their individuality. This is a numerical vibration:
- vowels;
- consonants;
- the sum of all letters.

These numerical values, taken together, characterize the most important aspects of the personality.

There is also a sound vibration of the name, because life is a continuous movement. That is why it has its own vibration. Each name has its own vibration. Throughout life, its meaning is gradually transferred to the owner. Scientists believe that the lower threshold of such vibrations is at 35,000 vibrations per second, and the upper threshold is at 130,000 / s. Those people who have the highest rate are resistant to various kinds of infections. They also have high levels of moral attitudes.