4.1. The impact of noise, ultrasound and vibration on the human body

ATP sources of noise and vibration are internal combustion engines, metalworking and woodworking machines, compressors, blacksmithing hammers, ventilation systems, brake stands, etc. Ultrasound sources are mainly ultrasound settings for cleaning and washing parts, mechanical processing of fragile and solid metals. , flaw detection, etching.

Noise, ultrasound and vibration, both individually and in aggregate have a negative effect on the human body. The degree of harmful effects depends on the frequency, level, duration and regularity of their action is essential and individual features of a person are essential.

Noise by affecting the central nervous system, hearing organs and other organs cause irritation, leads to fatigue, weakened attention, impairs memory, slows down mental reactions, prevents the perception of beneficial signals. For these reasons, under production conditions, intensive noise can contribute to the occurrence of injuries, a decrease in quality and productivity. The noise contributes to the development of hearing loss and deafness. Intense noise often causes people headaches, dizziness, feeling of fear, unstable emotional state. Under the influence of noise, the acuity of sight is dulled, the rhythms of breathing and cardiac activity change, arrhythmia appears, sometimes changes arterial pressure. The noise leads to a violation of the secret and engine function of the stomach, therefore, among working noisy production cases, cases of gastritis, ulcerative disease. Sometimes he is the cause of insomnia.

Sound oscillations are perceived not only by hearing organs, but also directly through the bones of the skull (bone conductivity). The level of sound pressure transmitted due to bone conductivity, almost "30 dB less than the level perceived by the hearing authorities. However, high levels The sound of bone conductivity increases significantly, respectively, the harmful effects of noise on the human body increase. When the audio pressure level of 130 dB and more (pain threshold), there is a pain in the ears, the sound is no longer heard. At the level of more than 145 dB, a breakpoint breakpoint is possible. At higher levels, deaths are possible.

The harmful effect of vibration is expressed in the form of increased fatigue, headaches, the appearance of itching, nausea, the sensation of the shaking of internal organs, pain in the joints, nervous excitement with depression, violation of coordination of movement, changes in the work of nervous and cardiovascular systems. The prolonged impact of vibration can cause vibration disease with a spasm of blood vessels of limbs, muscle damage, joints, tendons, disruption of the metabolic process in separate organs and the body as a whole. Vibration can lead to heart disease and diseases of the central nervous system.

Especially dangerous vibrations with frequencies, close or equal frequency of their own oscillations of the human body or its individual parts, organs, it is established that fluctuations with a frequency of 5-6 Hz are extremely unpleasant. They act on the heart of the heart. At frequencies 4-9 Hz oscillations are resonant for the stomach, brain and liver body, at 30-40 Hz for hands, 60-90 Hz for the eyeball, and 250-300 Hz for skull. Vibrations with a frequency of up to 4 Hz affect the vestibular apparatus and the central nervous system and cause a disease called "Sea disease".

Prolonged impact of both the general and local vibration can lead to partial or complete loss of ability to work.

The impact of ultrasonic oscillations on the human body occurs through air, liquid and directly through objects under the influence of ultrasound. The physiological effect of ultrasound on the human body causes a thermal effect and alternating pressure in the tissues. In contact with ultrasonic converters through liquid mediums with the intensity of sound 2-10 W / cm 2 people may be subjected to biological effects. In addition, there is noise near the equipment generating ultrasound oscillations. The overall level of sound pressure during the ultrasonic cleaning of parts near the equipment and the power of the generator of 2.5 kW reaches 97-112 dB, and when welding 125-129 dB.

The systematic impact of ultrasonic waves on the human body causes quick fatigue, ears pain, headaches, vomiting, violates the coordination of movements, develops neurosis and hypotension. There is a reduction in the pulse frequency, several slow motion reflexes, sleep disorders, poor appetite, dry mouth and "obedientness" of a language, abdominal pain.

4.2. Production noise rationing

In accordance with the classification of noise set by GOST 12.1.003-83 "CBST. Noise. General security requirements ", noises share by the nature of the spectrum on broadbandhaving a continuous spectrum, more than one octave width, and tonalwith discrete tones in the spectrum.

By temporary characteristics Noise are divided by permanent, whose sound pressure level for an 8-hour working day (working shift) varies in time no more than 5 dBA, and non-permanent (more than 5 dBA). Non-permanent noises in turn are divided into intermittent (fluctuated in time) and impulse.

Intermittent noise has a stepwise changing level of sound pressure (5 dba and more), and the duration of the intervals during which the level remains constant, is 1 s. and more. The noise fluctuating in time has a sound pressure level continuously changing in time. Pulse noise is a noise consisting of one or more audible signals, each duration of less than 1 s. At the same time, sound pressure levels differ at least 7 dBA.

For broadband noise permissible levels sound pressure in octave frequency bands, sound pressure levels and equivalent sound pressure levels. At workplaces should be taken in accordance with GOST 12.1.003-83 (Table 31).

For tonal and impulse noise measured by soundmark on the characteristic "Slow", permissible sound pressure levels, sound levels and equivalent sound levels should be taken by 5 dB fewer values \u200b\u200bindicated in Table. 31. For the noise created in the premises of air conditioning installations, ventilation and air heating, these characteristics are taken by 5 dB fewer values \u200b\u200bspecified in Table. 31, or actual soundproof levels in these rooms, if the latter do not exceed the values \u200b\u200bindicated in Table. 31 (amendment for a tonal and impulse noise in this case should not be taken).

The limit values \u200b\u200bof the noise characteristics of manual pneumatic and electrical machines should be taken in accordance with the requirements of GOST 12.2.030-83 (Table 32).

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1 For an octave strip The upper boundary frequency F B is equal to the double bottom boundary frequency F H, i.e. f V / F H, and each octave band is characterized by a medium-meter frequency

4.3. Noise fighting events

The fight against the noise on ATP should be started at the stage of their design or reconstruction. For this, the following are used. architectural and planning collective methods and means of protection: rational acoustic solution to the planning of buildings and general planners of objects; rational placement of technological equipment, machines and mechanisms; rational placement of jobs; Rational acoustic planning of zones and vehicle movement mode; Creating noise-proof zones in various locations of man.

When developing a master plan of ATP, the engine testing station, blacksmith and other "noisy" cues focus in one place on the periphery of the ATP territory, have them from a leeward side with respect to other buildings and residential array. Around the "noisy" workshops, it is advisable to create a green noise zone.

As an acoustic means of protection against noise, it is used: soundproofing (sound insulation of the fencing of buildings and premises, soundproofing casing and cabins, acoustic screens, weiglocks); sound absorption (sound-absorbing cladding, voluminous sound absorbers); Vibration insulation (vibration-insulating supports, elastic gaskets, structural breaks); damping means (linear and nonlinear); Silencers of noise (adsorption, jet, combined). Some characteristics of soundproofing and sound-absorbing means are shown in Table. 33-35.

TO organizational and technical means and methods of collective protection GOST 12.1.029-80 "SSBT. Means and methods of protection against noise. Classification "Related: The use of low-noise technological processes (for example, replacing a pneumatic riveting hydraulic); Equipment of noisy machines with remote control and automatic control (for example, removal of the control panel into a separate room or a cabin in compressor and at the engine test stations); the use of low noise machines; the change in the structural elements of the machines, their assembly units (replacement of the impact interaction of parts of the unwound, reciprocating movement rotational, the elimination of the resonant phenomenon by using minimum tolerances in the articulous parts, impassableness of rotating and moving parts and machine components); Improving car repair and maintenance technology; The use of rational modes of labor and recreation of workers in noisy sites. When these tools and methods are ineffective, the means of individual protection against noise should be used: antioxide liners and headphones (Table 36).

4.4. Rationing of ultrasound and protection against its harmful effects

Permissible levels of sound pressure at workplaces near ultrasound settings should, according to GOST 12.1.001-83 "SSBT Ultrasound. General security requirements, "match the following values:

Medium meterometric frequencies

third-solid stripes, kHz ............... 12,5 16 20 25 31.5-100

Sound pressure levels, dB ............ 80 90 100 105 110

Note. For the third-stroke strip

The values \u200b\u200bare set for ultrasound exposure duration for an 8-hour working day (shift). With the duration of ultrasound exposure less than 4 hours per shift, according to CH 245-71, sound pressure levels increase:

Total ultrasound exposure duration

in shift, min .................................... .. 60 - 240 20 - 60 5 - 15 1 - 5

Amendment, dB .............................. .. + 6 +12 +18 +24

In this case, the duration of exposure to ultrasound should be justified by calculation or confirmed by technical documentation.

The main activities to reduce the harmful effects of elevated ultrasound levels on the human body are:

reduction of harmful radiation of sound energy in the source;

localization of ultrasound constructive and planning solutions;

organizational and preventive measures;

use of personal protective equipment for working.

the use of soundproof housings, semi-fuses, screens;

placement of industrial equipment in individual rooms and cabins;

device of the blocking system that turns off the ultrasound source generator in the soundproofing;

remote control;

facing individual premises and cabbage sound-absorbing materials.

Soundproofing casing can be made of 1- or 2-millimeter sheet steel or duralumin, plated rubberoid, a technical rubber with a thickness of 3-5 mm, synthetic sound-absorbing materials or coated with anti-lastic mastic. You can use for the manufacture of housings and getinaks with a thickness of 5 mm. Technical openings (windows, covers, doors) soundproof housings must be sealed around the perimeter using rubber, and for dense closure there are special locks or clamps. From ultrasound baths and gears, housings must be isolated with rubber gaskets with a thickness of at least 5 mm. Elastic sound-insulating casing can be performed from three layers of rubber 1 mm thick each. Screens are made of the same materials as housings. Plexiglas are used for the manufacture of transparent screens, 3-5 mm thick.

Organizational and preventive measures Includes instructions on the nature of the impact of ultrasound and measures of protection, the choice of rational modes of labor and recreation.

To protect the human body from ultrasonic oscillations, when using ultrasonic baths, eliminate the direct contact of the body parts with the oscillating medium. During the change of the processed parts and during the loading period, they are turned off in a bath or unloading from them, the ultrasonic emitter is turned off or the special elastic coating holders are used. When contacting with the converter processed by parts and voiced liquid use personal protective equipment: Special gloves (rubber with cotton pad) or two pairs of gloves (internal cotton or woolen, outdoor - rubber) During operation, wetting of internal cotton or woolen gloves is not allowed. In cases where it is impossible to reduce the noise created by the ultrasonic installation, to permissible limits, persons directly engaged in the installation maintenance, should issue personal protective equipment from noise (for example, headphones, inserts)

4.5. Permissible levels of vibration and protection against its harmful effects

Hygienic norms of vibration, affecting a person under production conditions, are established by GOST 12.1.012-78 (Table 37-39)

For the total technological vibration in the workplaces of warehouses, canteens, household, duty and other industrial premises, where there are no machines generating vibration, its valid values \u200b\u200b(see Table 38) must be multiplied by the coefficient of 0.4, and the levels are reduced by 8 dB.

For general technological vibration in the workplaces of design bureaus, laboratories, training points, computing centers, health care, office premises, work rooms and other premises for mental labor workers, permissible vibration values \u200b\u200bmust be multiplied by the ratio of 0.14, and the levels are reduced by 17 dB.

With the methods of collective protection (GOST 12.4.046-78, "CSBT Methods and means of vibration protection. Classification") Vibration reduce, affecting the source of excitation, or on the paths of its propagation from the excitation source. At the same time, the decrease in vibration is achieved by the elimination of resonant phenomena, an increase in the strength of structures, a thorough assembly, balancing, eliminating too large backlash, equilibrating the masses, using vibration insulation and vibration, remote control, etc.

Organizational measures are of great importance, including control over the installation of equipment, proper operation, timely and qualitative planning and preventive service and repair.

As individual protection products Hands with vibrations are recommended mittens and gloves, liners and gaskets. Industry manufactures Cotton Mittens Anti-Vibrating, on the palm part they have a flip-rubber gasket. To protect the legs, special shoes should be used on the vibrational sole and knee pads made of microporous rubber by pressing the press form. The effectiveness of special vibration shoes is as follows:

Mediterraneanometric frequency of the octave strip, Hz 16.0 31.5 63.0

Efficiency of vibration protection, dB, not less than 7 10 10

Bibs, belts and special costumes are used to protect the body.

4.6. Measuring noise, ultrasound and vibration

The noise in the workplace of the industrial premises is measured in accordance with the requirements of GOST 20445-75 and GOST 23941 - 79. The noise-1m tumors can be used as the measuring equipment, W-1, noise meters and vibration meters, Ishv- 2, VSV-003, Noiseibrometric Kits KWC-1, IRK-and, as well as low-frequency vibration measuring equipment NVA-1 and VBM-1 type vibrometer

Ultrasound levels are measured by our industry a set of portable equipment for measuring sound to a frequency of 50,000 Hz.

From foreign equipment for measuring noise levels, ultrasound and vibrations, kits of the Danish company "Broul and Kier" and the company GDR "RFT" can be recommended.

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

Permissible noise levels at permanent jobs and in worksheets in industrial premises and in the enterprise are established by the current standard. The limit values \u200b\u200bof 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 methods are widely used.

When planning ATP "Noisy", cores focus in one place and have a leeward side with respect to other buildings. Around the "noise" workshops create a green noise protective zone. The following remedies for noise protection are used as acoustic: sound insulation, vibration insulation, noise silencers. Applicable tabs and headphones are used as the means of individual protection against noise on ATP.

Microclimate working zone

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

as well as ambient temperature.

Increased humidity of the body of the body makes it difficult by evaporation when high temperatures Air and helps overheating, and at low temperatures, on the contrary, enhances the heat transfer, contributing to the supercooling.

Intensive noise effect on the human body adversely affects nervous processes, promotes the development of fatigue, changes in the cardiovascular system and the appearance of noise pathology, among the diverse manifestations of which leading clinical sign It is a slowly progressive decline in hearing by the type of cochlear neuritis.

In production conditions, noise sources are working machines and mechanisms, manual mechanized tools, electric machines, compressors, forge-presses, lifting and transport, auxiliary equipment (ventilation plants, air conditioners), etc.

Permissible noise characteristics of workplaces are regulated by GOST 12.1.003-83 "Noise, General Safety Requirements" (Change II.III.89) and Sanitary Normats of Permissible Noise Levels at Work Places (CH 3223-85) with changes and additions from 29.03.1988 of year №122-6 / 245-1.

By the nature of the spectrum of noises are divided into broadband and tonal.

According to the temporary characteristics of the noise are divided into permanent and non-permanent.In turn, non-permanent noises are divided into time fluctuating, intermittent and impulse.

As the characteristics of constant noise at workplaces, as well as to determine the effectiveness of measures to limit its adverse effects, the levels of sound pressure in decibels (dB) in octave bands with medium-meter frequencies 31.5 are taken; 63; 125; 250; 1000; 2000; 4000; 8000 Hz.

As a general characteristic of noise at workplaces, an estimate of the sound level in dB (A) is used, which is the average value of the frequency response of sound pressure.

The characteristic of non-permanent noise in the workplace is the integral parameter - the equivalent sound level in dB (A).

The main activities to combat noise are technical measures that are held in three main areas:

• - eliminating the causes of noise or reduce it in the source;
• - weakening noise on transmission paths;
• - Direct protection of working.

The most effective means of reducing noise is the replacement of noisy technological operations on low noise or completely silent, but this path of struggle is not always possible, so it is of great importance to reduce it in the source. The reduction of noise in the source is achieved by improving the design or scheme of the part of the equipment that produces noise, use in the design of materials with low-acoustic properties, equipment at the noise source of an additional soundproofing device or a fencing located as close to the source.

One of the most simple technical means to combat noise on the transmission paths is a soundproofing casing that can close a separate noisy machine knot.

The significant effect of reducing noise from the equipment gives the use of acoustic screens, harboring the noisy mechanism from the workplace or the maintenance zone of the machine.

The use of sound-absorbing cladding for finishing the ceiling and walls of noisy premises leads to a change in the noise spectrum towards lower frequencies, which even with a relatively small level of level decreases significantly improves the working conditions.

Considering that with the help of technical means it is not always possible to solve the problem of reducing noise levels, much attention should be paid to the use of personal protective equipment (antifones, plugs, etc.). The effectiveness of personal protective equipment can be ensured by their correct selection depending on the levels and spectrum of noise, as well as control over the conditions of their operation.

Definition of concept. The prolonged impact of production noise on the body of working is characterized by a specific damage to the auditory analyzer and non-specific damage to the nervous, cardiovascular, digestive and endocrine Systems and polymorphism of the clinical picture.

The relevance of the question. In Russia, professional hearing loss in the structure of professional pathology is 9-12% and ranks 3rd after the defeat of the nervous system and the musculoskeletal system and professional dusty pathology (in the Omsk region - on average over the past 5 years 15.6% and 4- E place).

Sinkable production: extractive, wood, metal-, stone processing industry, weaving production, machine, air and shipbuilding, etc.

Sinkable professions:miner, penetrations, miners, rivests, grinders, polishers, concreteers, sandrafts, sharpeners, locksmiths, testers of motors, kovelschiki, chasokers, hammers, blacksmiths, tinsmiths, medical, sheets, etc.

Etiology of noise lesions.

The effect of noise in many cases is combined with the effects of vibration, dust, toxic and irritant substances, adverse factors of micro and macroclimate, with forced uncomfortable, unrelated working position of the body, physical overvoltage, increased attention, neuro-emotional overvoltage, which accelerates the development of pathology and causes Polymorphism of the clinical picture.

Noise sources are engines, pumps, compressors, turbines, pneumatic tools, hammers, crushers, machines, etc.

Distinguish:

by frequency:

low - 200-2000 Hz,

average - 2000-4000 Hz and

high-frequency noise - 4000-8000 Hz;

by temporary characteristics:

stable - with fluctuations in the intensity of no more than 5 dB and

impulse - with sharp changes in intensity (more aggressive);

by duration of exposure:

short-term I.

long existing noises.

Pow Shuma - 80 dBA in an octave strip with a medium-meter frequency of 1000 Hz. The remittant of noise for a particular employee is established taking into account the severity and tensions of labor and, depending on this, can be from 60 to 79 dBA.

With the intensity of production noise in 85 dBA, professional touginess is detected in 5% of employees, at 90 - in 10% at 100 - in 12%, at 110 - in 34%.

Pathogenesis of noise lesions.

The industrial noise exceeding the remote control has a two-way and non-specific effect on the body.

1. Specific actionnoise affects a rumor analyzer, its sound pending part, starting with the spiral body of a spiral organ, which are receptors for neurons of spiral ganglium and, ending with the neurons of the crust of Geshley temporalwhere the cortical end of the auditory analyzer is located, which leads to the development of professional hearing loss. Dystrophic (exchange, reversible), and then destructive (structural, small or irreversible) changes in the auditory analyzer develop due to the long-term operation of the hearing organ in the mode of increased noise load, an increased afferent impulse, in depleting mode. A certain contribution to the development of professional hearing loss introduces 1) mechanical factor, 2) central violations of the trophic of the auditory analyzer, 3) vascular disorders.

The morphological basis of professional hearing loss is mainly necrotic changes in the Cortium organ and spiral ganglia. Combined action Noise and vibration causes degenerative changes in the vestibular analyzer - the oholite apparatus and ampoules of semicircular channels, which causes the vestibular syndrome.

2. The nonspecific effect of noise affects the functions:

CNS - up to epileptiform seizures;

digestive system - up to ulcerative defects;

hearts - up to myocardial infarction;

4) vessels - up to an acute circulatory disorder in myocardium, brain, pancreas and other ischemic or hemorrhagic type organs.

Changes in listed above and other organs and systems are developing on neuro-humoral mechanism. Overflowing production noise is a stress factor. A nonspecific hypothalamic-pituitary-adrenal system with a release and hit to the circulating blood of biologically active substances, exposed to smooth muscle blood vessels (with the exception of vessels and capillaries), is involved in the response to a long-term effect of noise. their spastic state, ischemia of tissues and organs, hypoxia, acidosis, dystrophic (reversible), and in the future destructive (small or irreversible) changes in various tissues and organs, to greater in organs and systems with genotypically and / or phenotypically deterministic increased elevated Weakness and vulnerability to the "strength test" through a multiple and long-lasting circulatory disorder in them.

Classification of noise lesions.

Only changes are classified due to the specific effect of noise on the auditory analyzer, namely professional hearing loss. There are 4 and 5-grade classification of professional hearing loss in V.E. Sostapkovich and N.I. Pononarevoy, based on the severity of reduction of hearing acuteness at low frequencies (spoken speech range), high frequencies And at the perception of a whisper speech.

Recently, in otolaryngological practice, allocate:

initial signs of impact of noise on the hearing body (I and II degree of hearing loss in V.E. Sostapkovich, etc.);

easy reduction of hearing - I - I degree (III degree of hearing loss in V.E. Sostapkovich, etc.);

a moderate decline in hearing - II degree (IV degree of hearing loss in V.E. Sostapkovich, etc.);

a significant reduction in hearing - III degree (V degree of hearing loss in V.E. Sostapkovich, etc.).

Also distinguished:

• - sudden hearing loss (developing for 1 day),
• - Ostly (1-2 weeks),
• - subacted (for 3 weeks),
• - chronic (gradually).

Exemplary diagnosis of specific noise lesion: duplex neuro-sensory hearing loss (professional disease).

Noise and vibrations exceeding the volume and frequency of sound oscillations are professional harm. Noise is a combination of sounds of various intensity and frequency, which has an annoying and harmful effect on the human body. Under the influence of noise in humans, blood pressure can change, the operation of the gastrointestinal tract, and its long-term action in some cases leads to partial or complete loss of hearing. The noise affects the labor productivity of workers, weakens attention, causes hearing loss and deafness, irritates the nervous system, as a result of which susceptibility to danger signals is reduced, which can lead to an accident.

The noise is distinguished Shock (forging, riveting, stamping, etc.), Mechanical (friction and bias of nodes and parts of machines), Gas and Hydrodynamic (noise in devices and pipelines at high air, gas and liquid motion speeds).

Noises are classified by the nature of the spectrum (on broadband, with a continuous spectrum of more than one octave wide; tonal, in the spectrum of which there are audible discrete tones); According to the temporary characteristics (for permanent, the sound level of which for an 8-hour working day changes in time by no more than 5 dB in measurements on the time characteristic of "slowly" noiseomer according to GOST 17187-71; non-permanent, the sound level of which for the 8-hour working A day varies in time at least 5 dB when measuring the time characteristic of the "slowly" noiseomer according to GOST 17187-71).

In addition, non-permanent noises are divided into:

· I fluctuated in time, the sound level of which continuously changes in time; intermittent, the sound level of which drops sharply to the level of background noise;

· Pulse, consisting of one or more audible signals each duration less than 1 s, with sound levels in dB when the characteristics of the "slow" and "impulse" of the noiseomer in accordance with GOST 17187-81 differ at least 10 dB.

The characteristic of constant noise in the workplace is the levels of sound pressures in octave stripes (in dB) with medium-meterometric frequencies 63, 125, 250, 500, 1000, 2000, 4000, 8000 indefinite by the formula

Where: p is the rival size of sound pressure, pa;

The 3-10-5-threshold value of the standard sound pressure, Pa.

When measuring noise on a scale and noiseomers according to GOST 17187-81 R Take as Ra Defined on the root-mean-square magnitude of sound pressure, taking into account correction AND Noiseomer (in PA).

The characteristic of non-permanent noise in the workplace is equivalent (by energy) noise level (in dB), determined according to GOST 20445-75.

The minimum power of the sound that is perceived by the human ear is called Threshold audible.The greatest power of the sound, the excess of which leads to a feeling of pain, is called Painful threshold. The range of sounds perceived by the ear of a person is laid in the scale of 0 ... 130 dB. The lower limit of the scale corresponds to the threshold of hearing, the upper - painful threshold. Noise with a level of 130 ... 150 dB is able to cause mechanical damage Hearing organs. A harmless (reference) level of the greatest volume of noise for a person is 70DB (with a frequency of oscillations of 1000 Hz).

In physical nature, vibrations as well as noise is the oscillatory movements of material bodies with frequencies within 12.-. 8000 Hz, perceived by a person with its direct contact with the oscillating surfaces.

Vibration - oscillations of parts of production equipment and pipelines arising from unsatisfactory mounting, poor balancing of moving and rotating parts of machines and installations, work, shock mechanisms, etc. Vibration is characterized by a frequency (T-1) of oscillations (in Hz), amplitude ( in mm or cm) acceleration (in m / s). At a frequency of oscillations, more than 25 Hz vibration has an adverse effect on the nervous system, which can lead to the development of heavy nervous disease - vibration disease.

By analogy with the noise, the intensity of vibration can be measured by relative values \u200b\u200b- decibels and characterize:

· The level of oscillatory speed by the formula

Where:V.-colt speed, cm / s;

VO.- the title value of the oscillatory speed, adopted per unit of comparison and equal to 5 * 10-5 cm / s with sound pressure P \u003d 2-10-5 Pa and the amplitude of the displacement of 8 * 10-10 cm;

· The level of oscillatory acceleration by the formula

Where: a - oscillatory acceleration, cm / c2;

A0, - the threshold value of the oscillatory acceleration, taken over the comparison unit and equal to 3 * 10-2 cm / c2 with sound pressureP.\u003d 2 * 10-5 Pa and offset amplitude 8 * 10-10 cm.

By the number of harmful works on construction, which form noise and vibration (concussion) include work related to the use of manual pneumatic machines, vibrators, parquet-striking and grinding, machines, pile immersion operations, loosening frozen soil, etc. Vibration distinguishes - General and local. Common belongs to the vibration of the design or the unit, on which there is a person. Local vibration arises from a manual machine, which is in the hands of a worker, or an element of the machine.

Maximum permissible levels of general vibration installed for speed both in absolute and relative values \u200b\u200bover the frequency spectrum comprising six octave frequency bands; with medium megometric values \u200b\u200bof frequencies 2; four; 8; 16; 31.5 and 63 Hz with a movement amplitude with harmonic oscillations 3,11 ... 0.005 mm and the rms value of the oscillatory speed of 11.2 ... 2 mm / s. The maximum allowable values \u200b\u200bof local vibrations at a rotational speed of 1200-6000 min are 20-100 Hz with an amplitude of oscillations of 1.5-0.005 mm.

The sound pressure level is measured by noiseomers: type W-63 (IRPA), W-ZM, ICHV (with an interval of sound pressure level 30 ... 140) and Ash-2M noise spectrum analyzers, PF-1, 0-34 (with measurement interval 40 ... 10,000). Most wide use Received a sound meter type W-ZM. The device is designed to measure sound pressure levels and noise levels. Local vibration is determined using a low-frequency (with a vibration measurement interval of 1.4 ... 350) and vibration metering equipment (with a measurement interval of 70 ... 130) NVA-1 vibrarographs, WP-2. The overall vibration, amplitude and frequency of oscillation (the oscillation of the structures on which the person is located) is measured by electronic devices WEP-4, Vi6-5 MA, K.001, together with oscilloscopes N-700, H-004, and others. The main recording mechanism in the instrument is Vibration sensor seismic type VD-4. During the measurement, the sensor is installed on a vibrating surface.

It should be noted that the fight against noise and vibration represents a comprehensive problem that affects the interests of many specialists, builders, designers, doctors and acoustics. For protection against noise and vibration use general and individual means.

TO General means protection First of all, the improvement of building machines and the technological process (for example, the replacement of riveting electric welding), the planning of industrial premises and isolation of noisy production processes, the use of soundproofing and sound-absorbing materials in machines, walls, overlaps and partitions. Effective tool The protection against the propagation of noise is the shelter of the machine with a casing with sound-absorbing materials (such as noise silencers) and the transition to the remote control of the vibropneumoprocession. Zones with sound level above 85 dB should be indicated by safety signs, and working are provided with personal protective equipment. In zones with octave sound pressure levels, over 135 dB, people stay are prohibited.

Any kind of fencing devices, vibration-eyed, vibration and vibrarous devices of automatic control, alarm and remote control can be assigned to vibration protection products.

TO Personal protective equipment from harmful influences Noise includes anti-coax, helmets, headphones, liners, and from the effects of vibration - the use of vibrational shoes, special gloves and mittens (when using manual vibrators).

The impact of ultrasound (with mechanical processing of materials, welding, tinning, etc.) on the human body occurs through the air and directly with the contact of the person with objects. The physiological effect of ultrasound causes a thermal effect in human tissues (temperature increase) and alternating pressure, as well as fast fatigue, ears pain, violates the balance and develops neurosis and hypotension.

To the means of eliminating and reducing the harmful effects of ultrasound also includes constructive and planning solutions aimed at its localization. This is the use of soundproofing housings, semi-windows, screens, equipment accommodation in separate rooms and offices, a blocking system device that turns off the ultrasound source generator with a sound insulation, the use of remote control, the facing of individual rooms and cabbage sound-absorbing materials.

Organizational and prophylactic measures to protect against the harmful effects of elevated levels include the instructions of working, on the nature of the ultrasound action and rational regimes of labor and recreation.

Noise - a set of sounds of different frequency and intensity arising from the oscillatory movement of particles in elastic media (solid, liquid, gaseous); Perceived as obsessive and unpleasant sound.

The process of propagation of the oscillatory movement in the medium is called a sound wave, and the area of \u200b\u200bthe medium in which sound waves are applied - the sound field.

By the nature of the occurrence, the production noise is divided into:

Shock

Occurs when stamping, riveting, forging, etc.

Mechanical

Most often occurs in chemical production. It occurs when friction and bias of nodes and parts of machines and mechanisms.

Aerodynamic

It is also widespread in the chemical industry. Accompanies the work of devices, pipelines, turbines, fans.

The frequency composition of noise is called spectrum . If you enlarge the frequency is twice, then the person perceives this raising of the tone to a certain value called the octava.

Octave - The frequency range in which the upper border is twice as much longer.

The noise frequency is divided into:

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

- mid-frequency (500-100 Hz) - noise of cars, machine tools, aggregates.

- high frequency (above 800 Hz) - all ringing, hissing, whistling noise, which are characteristic of the work of the shock aggregates, move the flow of air and gases.

By temporary characteristics, noise is divided into:

- Constant - noise, the sound level of which is changing less than 5 degree to the 8-hour working day.

- Unstable - Noise, the sound level of which is changing more than 5 degree to the 8-hour working day. Non-permanent noises, in turn, are:

- intermittent - The sound level of which stepwise changes by 5 degree and more. Moreover, the duration of the interval during which the sound level remains constant, must be more than 1 second.

- pulse - The interval in which the sound level remains constant, is less than 1 second. Pulse 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 frequency of oscillations will give different sound intensity.

Pain threshold: I bp \u003d 10 2 W / m 2; Threshold of hearing: i cl. \u003d 10 -12 W / m 2.

Sound intensity level (L i) \u003d 10lg (I / I 0), where i is the intensity of the propagating sound wave; I 0 - threshold of hearingness.

Sound Pressure (P) - The difference between atmospheric pressure and pressure at this point of the sound field.

Threshold of hearing 2 * 10 -5 pa; Pain threshold 2 * 10 2 pa.

The audio intensity level can be associated with the sound pressure of the following formula:

L p \u003d 20lg (P / P 0)

where r - sound pressure, p 0 - threshold of hearingness.

All these values \u200b\u200bcannot give full information about the volume of sound, since with the same sound strength, but with different frequency the volume of the sound will be different. Therefore, the volume level is measured, which is measured in the backgrounds.

Vibration - These are the oscillations of solid bodies - parts of the apparatuses, machinery, equipment, structures, perceived by the human body as concussion. Often vibrations are accompanied by audible noise.

Local Vibration is characterized by oscillations of the tool and equipment transmitted to individual parts of the body.

For general Vibrations of oscillations are transmitted to the whole body from working mechanisms in the workplace through the floor, seat or work site. The most dangerous frequency of general vibration lies in the range of 6-9 Hz, since it coincides with its own fluctuation frequency internal organs man, resulting in a resonance.

The main parameters characterizing vibration:

- frequency (I) (Hz);

- ambacious amplitude (A) - the magnitude of the greatest deviation of the oscillating point on the equilibrium position (M)

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

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

Since the range of changes in the parameters of vibration from the threshold values \u200b\u200bat which it is not dangerous, to valid - large, it is more convenient to measure the valid values \u200b\u200bof these parameters, and the logarithm ratio of valid values \u200b\u200bto the threshold. Such a magnitude is called the logarithmic level of the parameter, and the unit of its measurement is decibel.

So the logarithmic level of vibrations is determined by the formula:

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

Noise reduction can be achieved by the following methods:

Reducing noise in the source of its formation

Insulation of noise sources with sound insulation and sound absorption;

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

Application of personal protective equipment.

Protection against aerodynamic noise arising from the operation of ventilation installations, air conditioners, compressors, when blending parts with compressed air for cleaning them, drying and with other technological operations requires great effort and is often insufficient. The main decrease in noise is achieved mainly sound insulation of the source or the use of silencers, which are installed on the air ducts. Suction paths, emission and air recurring highways.

Soundproofingthese are special features of obstacles (in the form of walls, partitions, housings, screens, etc.), which prevent noise from the same room to another or in the same room. The physical essence of sound insulation is that the greatest part of the sound is energized from the enclosing structures.

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

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

Very often, special covers installed on aggregates are used to protect against noise. They are usually made of subtle aluminum, steel or plastic sheets. The inner surface of the casing is necessarily facing the sound-absorbing material. When installing the housing to the floor, rubber gaskets should be used. The casing can ensure noise reduction by 15-20 dB.

To protect those operating from the immediate (direct) effects of noise, screens that are installed between the noise source and the workplace are used. The acoustic effect of the screen is based on the formation of the shadow region, where the sound waves penetrate only partially. Screens are lined with sound-absorbing material with a thickness of at least 50-60 mm. Reducing noise in places protected by screens is 5-8 dB.

Of great importance for reducing noise and vibration has the correct planning of the territory and industrial premises, as well as the use of natural and artificial obstacles that prevent the spread of noise.

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

Vibration Isolation - This is a decrease in the level of vibration of a protected object, achieved by a decrease in the transmission of oscillations from their source. Vibration isolation is an elastic elements placed between the vibrating machine and its base.

Vibration shock absorbers are made of steel springs or rubber gaskets.

Foundations for heavy equipment, causing significant vibrations, are made beweded and isolated from all sides by cork, felt, slag, asbestos and other damping vibration materials.

To reduce the vibration of housings, fences and other parts made of steel sheets, a layer of rubber, plastics, bitumen, vibrating absorbing mastics are applied to them, which dispel the oscillation energy.

In cases where the technical and other measures fail to reduce the level of noise and vibration to permissible limits, individual means of protection apply. Mittens or gloves or gloves of the following types are used to protect hands from the effects of local vibration: with special vibration-protected elastic-demarfing liners, fully made from vibration-proof material (molding, molding, etc.), as well as vibration-proof gaskets or plates that are equipped with fines to hand .

To protect against vibration transmitted to man through legs, it is recommended to wear shoes on a felt or thick rubber sole.

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