Sources of noise and vibration are moving vehicles, compressors, ventilation systems. Noise, ultrasound and vibration worsen working conditions, have a harmful effect on the human body, contribute to the occurrence of injuries and lead to a decrease in the quality of car repairs and maintenance.

Permissible levels noise at permanent workplaces and in working areas in industrial premises and on the territory of the enterprise are established by the current standard. Limit values ​​of noise characteristics are regulated by GOST 12.2.030-83.

To combat noise, ultrasound and vibration, various means and methods of collective protection, architectural and planning methods, acoustic means and organizational and technical methods are widely used.

When planning ATP, "noisy" workshops are concentrated in one place and located on the leeward side in relation to other buildings. Around the "noise" workshops create a green noise protection zone. As acoustic, the following means of noise protection are used: sound insulation, vibration isolation, noise silencers. Anti-plague tabs and earmuffs are used as personal protection against noise at ATP.

Microclimate of the working area

The microclimate in the working area is determined by the combinations of temperature, humidity, air velocity acting on human organs,

as well as the temperature of the surrounding surface.

Increased humidity makes it difficult for the body to release heat through evaporation at high air temperatures and contributes to overheating, and at low temperatures, on the contrary, enhances heat transfer, contributing to hypothermia.

on the subject: "Life safety"

on the topic: “Industrial vibration and industrial noise. Their influence on a person

Perm-2007

Industrial vibration

Vibration is the reciprocating motion of a solid body. This phenomenon is widespread in the operation of various mechanisms and machines. Vibration sources: bulk conveyors, rotary hammers, electric motors, etc.

Basic vibration parameters: frequency (Hz), vibration amplitude (m), vibration period (s), vibration velocity (m/s), vibration acceleration (m/s²).

Depending on the nature of the worker's contact with vibrating equipment, local and general vibration are distinguished. Local vibration is transmitted mainly through the limbs of the arms and legs. There is also a mixed vibration that affects both the limbs and the entire body of a person. Local vibration occurs mainly when working with a vibrating hand tool or bench equipment. General vibration prevails in transport vehicles, heavy machinery manufacturing plants, elevators, etc. where floors, walls or equipment bases vibrate.

The effect of vibration on the human body. The human body is considered as a combination of masses with elastic elements that have their own frequencies, which for the shoulder girdle, hips and head relative to the supporting surface ("standing" position) are 4-6 Hz, the head relative to the shoulders ("sitting" position) - 25-30 Hz. For most internal organs natural frequencies lie in the range of 6-9 Hz. General vibration with a frequency of less than 0.7 Hz, defined as pitching, although unpleasant, does not lead to vibration disease. The consequence of such vibration is seasickness, caused by a violation of the normal activity of the vestibular apparatus due to resonance phenomena.

The systematic impact of general vibrations leads to a vibration disease, which is characterized by violations physiological functions organism associated with damage to the central nervous system. These disorders cause headaches, dizziness, sleep disturbances, decreased performance, poor health, and cardiac disorders.

Local vibration of low intensity can have a beneficial effect on the human body, restore trophic changes, improve functional state central nervous system, accelerate wound healing, etc.

With an increase in the intensity of oscillations and the duration of their impact, changes occur, leading in some cases to the development occupational pathology- vibration disease.

Permissible vibration levels.

The general vibration is normalized taking into account the properties of the source of its occurrence and is divided into vibration:

transport, which occurs as a result of the movement of cars on the terrain and roads;

transport and technological, which occurs during the operation of machines that perform a technological operation in a stationary position, as well as when moving through a specially prepared part of a production facility, an industrial site or wholesale depots;

Technological, which occurs during the operation of stationary machines or is transmitted to workplaces that do not have sources of vibration (for example, from the operation of refrigeration, filling and packaging machines).

· High requirements present when rationing technological vibrations in rooms for mental work (management, dispatching, accounting, etc.). Hygienic vibration standards are set for a working day lasting 8 hours.

The effect of vibration on the human body

Methods to reduce the impact of vibration on a person

To reduce the impact of vibrating machines and equipment on the human body, the following measures and means are used:

replacement of tools or equipment with vibrating working bodies for non-vibrating ones in processes, where possible (for example, replacing electromechanical cash registers with electronic ones);

application of vibration isolation of vibrating machines relative to the base (for example, the use of springs, rubber gaskets, springs, shock absorbers);

The use of automation in technological processes where vibrating machines work (for example, control according to a given program);

· the use of remote control in technological processes (for example, the use of telecommunications to control the vibroconveyor from an adjacent room);

Use of hand tools with anti-vibration handles, special footwear and gloves.

In addition to technical means and methods to reduce the impact of vibration on a person, it is necessary to carry out hygienic and therapeutic and preventive measures. In accordance with the regulation on the working regime of workers in hazardous professions, the total time of contact with vibrating machines, the vibration of which meets sanitary standards, should not exceed 2/3 of the working day.

To work with vibrating machines and equipment, persons under the age of 18 are allowed. Those who have received the appropriate qualifications, passed the technical minimum according to safety rules and passed a medical examination.

To increase the protective properties of the body, working capacity and labor activity, industrial gymnastics complexes, vitamin prophylaxis should be used (2 times a year, a complex of vitamins C, a nicotinic acid), special food. It is also advisable to carry out in the middle or at the end of the working day 5 - 10-minute hydro-procedures, combining baths at a water temperature of 38º C

Production noise

In various sectors of the economy there are sources of noise - these are mechanical equipment, human flows, urban transport.

Noise is a collection of aperiodic sounds of varying intensity and frequency (rustling, rattling, creaking, screeching, etc.). From a physiological point of view, noise is any adversely perceived sound. Prolonged human exposure to noise can lead to occupational disease like "noise disease".

According to its physical essence, noise is a wave-like movement of particles of an elastic medium (gas, liquid or solid) and therefore is characterized by the amplitude of the oscillation (m), frequency (Hz), propagation velocity (m/s) and wavelength (m). The loudness of the noise is determined by the subjective perception of the human hearing aid. The threshold of auditory perception also depends on the frequency range. Thus, the ear is less sensitive to low-frequency sounds.

The impact of noise on the human body causes negative changes primarily in the organs of hearing, nervous and cardiovascular systems. The severity of these changes depends on the parameters of noise, work experience in conditions of noise exposure, the duration of noise exposure during the working day, and the individual sensitivity of the organism. The effect of noise on the human body is aggravated by the forced position of the body, increased attention, neuro-emotional stress, and unfavorable microclimate.

The effect of noise on the human body. To date, numerous data have been accumulated that make it possible to judge the nature and features of the influence of the noise factor on the auditory function. The course of functional changes can have different stages. A short-term decrease in hearing acuity under the influence of noise from fast recovery function after the termination of the factor is considered as a manifestation of the adaptive protective-adaptive reaction of the auditory organ.

Adaptation to noise is considered to be a temporary decrease in hearing by no more than 10-15 dB with its restoration within 3 minutes after the cessation of the noise. Prolonged exposure to intense noise can lead to re-irritation of the cells of the sound analyzer and its fatigue, and then to a persistent decrease in hearing acuity.

It has been established that the tiring and hearing-damaging effect of noise is proportional to its height (frequency). The most pronounced and early changes are observed at a frequency of 4000 Hz and a frequency range close to it. In this case, impulse noise (at the same equivalent power) acts more unfavorably than continuous noise. Features of its impact significantly depend on the excess of the impulse level above the level that determines the background noise in the workplace.

The development of occupational hearing loss depends on the total time of exposure to noise during the working day and the presence of pauses, as well as the total work experience. Initial stages occupational lesions are observed in workers with an experience of 5 years, expressed (hearing damage to all frequencies, impaired perception of whispered and colloquial speech) - over 10 years.

In addition to the effect of noise on the hearing organs, its harmful effect on many organs and systems of the body, primarily on the central nervous system, in which functional changes occur before a violation of auditory sensitivity is diagnosed, has been established. Damage to the nervous system under the influence of noise is accompanied by irritability, memory loss, apathy, and depressed mood. Changes in skin sensitivity and other disorders, in particular, slow down the speed of mental reactions, sleep disorders occur, etc. For knowledge workers, there is a decrease in the pace of work, its quality and productivity.

NOISE - how harmful production factor- this is a set of sounds, different in amplitude and frequency, which arise as a result of an oscillatory process and are undesirable for a person.

Being a general biological irritant, noise not only affects the hearing aid (due to constant exposure to noise, an occupational disease can appear - hearing loss), but can lead to a disorder of the cardiovascular and nervous systems, contributes to the occurrence hypertension. In addition, it is one of the reasons for the rapid fatigue of the worker, it can cause dizziness, which in turn can lead to an accident.

At the design stage of buildings and premises in which noisy machines and equipment are to be installed, it is necessary to provide for the safety of production activities in terms of noise levels, for which the ability of sound waves to be reflected from surfaces or absorbed by them should be taken into account. The degree of reflection of a sound wave depends on the shape of the reflecting surface and the properties of materials (felt, rubber, etc.). The main part of the sound wave (energy) incident on them is not reflected, but absorbed. Features of the design and shape of the premises can lead to reverberation - multiple reflections of sound from the surfaces of the floor, walls and ceiling, which increases the sound time.

Noise reduction in industrial premises of enterprises Catering can be achieved by:

Applications of sound-absorbing materials;

The use of special shock-absorbing, noise-absorbing and sound-absorbing devices and devices;

Timely elimination of malfunctions that increase noise during equipment operation; timely prevention and repair of equipment;

Constant control over the fastening of moving parts of machines and mechanisms, checking the condition of cushion pads, lubrication, etc.;

Operation of the equipment in the modes specified by the manufacturer in the passport for the equipment;

Placement of workplaces, machines and mechanisms in such a way that the impact of noise on workers is minimal;

Placement of jobs for waiters, bartenders, bartenders in dining halls in the least noisy places, remote from the stage, acoustic systems;

Limitations on the output power of musical arrangements in the premises for visitors;

Organization of places for short-term rest of employees in rooms equipped with sound insulation and sound absorption;

Suspended ceiling devices.

VIBRATION - mechanical vibrations in elastic bodies or bodies under the influence of variable physical fields with a relatively small amplitude.

At catering establishments, in production shops and areas, vibration is observed during the operation of refrigeration units, lifting, transport and packaging equipment and other machines and mechanisms. The limit levels of local (local) vibration are set by GOST 12.1.012 - 90 SSBT. Vibration safety. General requirements".

Industrial vibration, characterized by a significant amplitude and duration of action, causes irritability, insomnia, headache, aching pain in hand.

In people dealing with a vibrating instrument, with prolonged exposure to vibration, the bone tissue is rebuilt: on radiographs, you can see stripes that look like traces of a fracture - areas of greatest stress, where the bone tissue softens, the permeability of small blood vessels, nervous regulation is disturbed, skin sensitivity changes. When working with a manual mechanized tool, acroasphyxia (a symptom of "dead fingers") may occur - loss of sensitivity, whitening of fingers, hands. When exposed to general vibration, changes in the central nervous system are more pronounced: dizziness, tinnitus, memory impairment, impaired coordination of movements, vestibular disorders, and weight loss appear.

If the level of vibration permissible for a person is exceeded, measures should be taken to reduce its parameters. First of all, it is necessary to reduce the vibration in the source itself, for example, to use special shock-absorbing devices and fixtures.

Individual protection against vibration of workers is provided by special shoes and gloves with elastic damping elements. Relaxing baths for hands and feet, massage, ultraviolet irradiation, industrial gymnastics are of great preventive importance. To strengthen the body's resistance to the harmful effects of vibration, workers are given vitamins.

The optimal alternation of periods of work and rest helps to reduce the harmful effects of vibration. Vibration-related work time is reduced (as a percentage of the total shift time) as the allowable vibration values ​​are exceeded. In addition, they provide for regulated breaks lasting 20 minutes in the first half of the shift and 30 minutes in the second.

All those working with vibration sources must undergo preliminary and periodic (at least once a year) medical examinations.

Noise, vibration are vibrations of material particles of a gas, liquid or solid. Production processes are often accompanied by significant noise, vibration and shaking, which adversely affect health and can cause occupational diseases.

The human auditory apparatus has unequal sensitivity to sounds of different frequencies, namely, the greatest sensitivity at medium and high frequencies (800-4000 Hz) and the least at low frequencies (20-100 Hz). Therefore, for the physiological assessment of noise, curves of equal loudness are used (Fig. 30), obtained from the results of studying the properties of the hearing organ to evaluate sounds of different frequencies according to the subjective sensation of loudness, i.e. judge which one is stronger or weaker.

Loudness levels are measured in phons. At a frequency of 1000 Hz, the volume levels are taken equal to the sound pressure levels. According to the nature of the noise spectrum, they are divided into:

tonal - one or more tones are heard.

By time, noises are subdivided into constant ones (the level for 8 hours a day changes by no more than 5 dB).

Non-constant (the level changes for 8 hours a day at least 5 dB).

The non-permanent are divided: those that fluctuate in time are constantly changing over time; intermittent - abruptly interrupted with an interval of 1 s. and more; pulse - signals with a duration of less than 1 s.

Any increase in noise above the threshold of hearing increases muscle tension, which means that it increases the expenditure of muscle energy.

Under the influence of noise, visual acuity is dulled, the rhythms of respiration and cardiac activity change, there is a decrease in working capacity, weakening of attention. In addition, noise causes increased irritability and nervousness.

Tonal (a certain noise tone dominates) and impulse (intermittent) noise are more harmful to human health than broadband noise. The duration of exposure to noise leads to deafness, especially when the level exceeds 85-90 dB, and first of all, sensitivity at high frequencies decreases.

Vibrations of material bodies at low frequencies (3-100 Hz) with large amplitudes (0.5-0.003) mm are felt by a person as vibration and shaking. Vibrations are widely used in production: compaction of the concrete mix, drilling of holes (wells) with perforators, loosening of soils, etc.

However, vibrations and concussions have a harmful effect on the human body, cause vibration disease - neuritis. Under the influence of vibration, a change occurs in the nervous, cardiovascular and osteoarticular systems: blood pressure, spasms of the vessels of the extremities and the heart. This disease is accompanied by headaches, dizziness, increased fatigue, numbness of the hands. Oscillations with a frequency of 6-9 Hz are especially harmful, the frequencies are close to natural vibrations of internal organs and lead to resonance, as a result, internal organs move (heart, lungs, stomach) and irritate them.

Vibrations are characterized by displacement amplitude A - this is the magnitude of the largest deviation of the oscillating point from the equilibrium position in mm (m); amplitude of vibrational velocity V m/s; amplitude of oscillatory acceleration a m/s; period T, s; oscillation frequency f Hz.

General vibration according to the source of its occurrence is divided into 3 categories:

• 1. transport (when moving across the terrain);
• 2. transport and technological (when moving indoors, at industrial construction sites);
• 3. technological (from stationary machines, jobs).

The most harmful vibration, the frequency of which coincides with the resonant frequency of the body, equal to 6 Hz, and its individual parts: internal organs - 8 Hz, head - 25 Hz, CNS - 250 Hz.

Vibration is measured with a vibrometer. Sanitary and hygienic regulation of vibration provides optimal working conditions for a person, and technical regulation ensures optimal working conditions for machines.

Methods of protection against noise and vibration are divided into groups. Architectural and planning methods: acoustic planning of buildings and master plans; placement of equipment and workplaces; placement of zones and mode of traffic; creation of noise protection zones. Acoustic means: sound insulation of equipment, buildings and premises; covers on equipment; soundproof booths, acoustic screens, enclosures; sound absorption by facings and piece absorbers; vibration isolation of supports and foundations, elastic pads and coatings of protected communications, structural gaps. Organizational and technical methods: low-noise machines; remote control of noisy machines; improving the repair and maintenance of machines; rationalization of work and rest regimes. Noise through windows can be reduced with glass blocks (“bricks” made of glass) and double, triple glazing or glass of different thicknesses that do not have a common divider (for example, 1.5 and 3.2 mm). Sometimes it is uneconomical or difficult to reduce noise to the standard (riveting, chopping, stamping, stripping, screening, grinding, etc.), then PPE is used: liners, headphones and helmets.

Noise- a set of sounds of different frequencies and intensities arising from the oscillatory motion of particles in elastic media (solid, liquid, gaseous); perceived as an obsessive and unpleasant sound.

The process of propagation of oscillatory motion in a medium is called a sound wave, and the area of ​​the medium in which sound waves propagate is called a sound field.

According to the nature of occurrence, industrial noise is divided into:

Shock

Occurs during stamping, riveting, forging, etc.

Mechanical

Most often found in chemical industries. Occurs during friction and beating of units and parts of machines and mechanisms.

Aerodynamic

It is also widely used in the chemical industry. Accompanies the operation of devices, pipelines, turbines, fans.

The frequency content of the noise is called spectrum . If the frequency is doubled, then a person perceives this increase in tone by a certain amount, called an octave.

Octave is the frequency range in which the upper limit is twice the lower limit.

The frequency of the noise is divided into:

- low frequency (20-350 Hz) - fan noise and motor hum.

- midrange (500-100 Hz) - the noise of machines, machine tools, units.

- high frequency (above 800 Hz) - all ringing, hissing, whistling noises that are characteristic of the operation of percussion units, the movement of air and gases.

According to temporal characteristics, noise is divided into:

- Constant - noise, the sound level of which during an 8-hour working day changes by less than 5 decimals.

- fickle - noise, the sound level of which during an 8-hour working day changes by more than 5 decimals. Intermittent noises, in turn, are:

- intermittent - the sound level of which changes in steps by 5 dB or more. Moreover, the duration of the interval during which the sound level remains constant must be more than 1 second.

- impulse - the interval in which the sound level remains constant is less than 1 second. Impulse noise is the most unfavorable.

The propagation of noise occurs with the help of a sound wave and is accompanied by a change in energy.

Sound intensity- sound energy transmitted per unit of time through a unit of surface: [I] \u003d W / m 2

Different vibration frequencies will produce different sound intensities.

Pain threshold: I b.p. \u003d 10 2 W / m 2; hearing threshold: I sl. \u003d 10 -12 W / m 2.

Sound intensity level (L i)= 10lg (I/I 0), where I is the intensity of the propagating sound wave; I 0 - hearing threshold.

Sound pressure (p) is the difference between atmospheric pressure and the pressure at a given point in the sound field.

Threshold of hearing 2*10 -5 Pa; pain threshold 2 * 10 2 Pa.

Sound intensity level can be related to sound pressure by the following formula:

L P =20lg(P/P 0)

where R - sound pressure, Р 0 – hearing threshold.

All these quantities cannot give complete information about the loudness of sound, since with the same sound strength, but at different frequencies, the sound volume will be different. Therefore, the loudness level is measured, which is measured in phons.

vibrations- these are vibrations of solid bodies - parts of apparatuses, machines, equipment, structures, perceived by the human body as tremors. Vibrations are often accompanied by audible noise.

local vibration is characterized by vibrations of the tool and equipment transmitted to individual parts of the body.

At general vibration vibrations are transmitted to the whole body from working mechanisms in the workplace through the floor, seat or work platform. The most dangerous frequency of general vibration lies in the range of 6-9 Hz, since it coincides with the natural frequency of vibration of the internal organs of a person, as a result of which resonance may occur.

The main parameters characterizing vibration:

- frequency (I) (Hz);

- displacement amplitude (A) - the value of the largest deviation of the oscillating point from the equilibrium position (m)

- oscillation speed , (V) (m/s)

- oscillatory acceleration (a) (m/s 2)

Since the range of changes in vibration parameters from threshold values ​​at which it is not dangerous to actual ones is large, it is more convenient to measure not the actual values ​​of these parameters, but the logarithm of the ratio of actual values ​​to threshold ones. This value is called the logarithmic level of the parameter, and the unit of its measurement is the decibel.

So the logarithmic level of vibration velocity is determined by the formula:

L V \u003d 20lg (V / V 0)

Noise reduction can be achieved by the following methods:

Reducing noise at its source

Isolation of noise sources by means of sound insulation and sound absorption;

Architectural and planning solutions that provide for the rational placement of technological equipment, machines, mechanisms, acoustic treatment of premises;

Use of personal protective equipment.

Protection against aerodynamic noise that occurs during the operation of ventilation units, air conditioners, compressors, when parts are blown with compressed air for cleaning, drying, and during other technological operations requires a lot of effort and is often insufficient. The main noise reduction is achieved mainly by soundproofing the source or by using silencers that are installed on the air ducts. suction ducts, ejection lines and air correspondence.

Soundproofing these are special barrier devices (in the form of walls, partitions, casings, screens, etc.) that prevent the spread of noise from one room to another or in the same room. The physical essence of sound insulation is that the largest part of the sound energy is reflected from the building envelope.

The soundproofing ability of barriers increases with an increase in their mass and sound frequency. In some cases, multilayer structures consisting of different materials have higher sound insulation than single-layer structures of the same mass. The air layer between the layers increases the soundproofing ability of the barrier.

In production conditions, often used together with soundproofing sound absorption . Porous materials absorb sound most effectively. This is due to the transition of the energy of oscillating air particles into heat generated as a result of their friction in the pores of the material. Nylon fiber, foam rubber, mineral wool, fiberglass, porous polyvinyl chloride, asbestos, porous plaster, cotton wool, etc. are used as sound-absorbing material.

Very often, special casings installed on the units are used to protect against noise. They are usually made from thin aluminum, steel or plastic sheets. The inner surface of the casing must be lined with sound-absorbing material. When installing the casing on the floor, rubber pads must be used. The casing can provide 15-20 dB noise reduction.

To protect workers from direct (direct) exposure to noise, screens are used that are installed between the noise source and the workplace. The acoustic effect of the screen is based on the formation of a shadow area behind it, where sound waves only partially penetrate. The screens are lined with sound-absorbing material with a thickness of at least 50-60 mm. Noise reduction in places protected by screens is 5-8 dB.

Great importance to reduce noise and vibration, it has the correct layout of the territory and production facilities, as well as the use of natural and artificial barriers that prevent the spread of noise.

To protect against vibration, vibration-absorbing and vibration-isolating materials and structures are widely used.

Vibration isolation- this is a reduction in the level of vibration of the protected object, achieved by reducing the transmission of vibrations from their source. Vibration isolation is elastic elements placed between the vibrating machine and its base.

Vibration dampers are made from steel springs or rubber pads.

Foundations for heavy equipment that cause significant vibrations are made deep and insulated on all sides with cork, felt, slag, asbestos and other vibration-damping materials.

To reduce the vibration of casings, guards and other parts made of steel sheets, they are covered with a layer of rubber, plastics, bitumen, vibration-absorbing mastic, which dissipate vibration energy.

In cases where technical and other measures fail to reduce the level of noise and vibration to acceptable limits, personal protective equipment is used. To protect hands from the effects of local vibration, mittens or gloves of the following types are used: with special vibration-protective elastic-demorphing inserts, completely made of vibration-protective material (casting, molding, etc.), as well as vibration-protective pads or plates that are equipped with attachments to the hand .

To protect against vibration transmitted to a person through the feet, it is recommended to wear shoes with felt or thick rubber soles.

Similar information.