Regulation of industrial noise. Methods and means of protection against noise.
Existing
two methods of normalization of the generated noise:
1. Rationing by sound level
pressure. 2. Rationing by level
sound.
1.It
the main normalization method for
constant noise is normalized here
sound pressure levels in octaves
strip with average geom frequencies (63,
125, 250, 500...8000Hz). Set of 8 valid
sound pressure levels called
limit spectrum. 2.This method
used for indicative evaluation
constant and intermittent noise,
In this case, we do not know the noise spectrum.
The sound level is related to the limit
spectrum dependence LA=PS+5.
For tonal and impulse noise
acceptable levels must be accepted
5 dB less than for constants.
The allowable noise dose is the dose
corresponding to the acceptable level
sound or acceptable equivalent
sound level. For intermittent noises
normalized parameter is equivalent
energy sound level constant
broadband non-impulse noise.
Noise control measures 1.
Construction and planning; 2.Constructive;
3.Reduce noise at the source of it
occurrence; 4. Organizational
Events.
Most
effective method of protection is
noise control v
its origin.
To reduce mechanical noise
need to be done in a timely manner
equipment repair, drum replacement
processes on unstressed, more widely apply
forced lubrication of rubbing
surfaces. Aerodynamic reduction
noise can be reduced by reducing the speed
gas flow, improved aerodynamics
construction, soundproofing and installation
mufflers. Electromagnetic noise
reduced by structural changes
in electrical machines.
wide
methods have been applied to reduce
noise along its path
by installing soundproofing
and sound-absorbing barriers in the form
screens, partitions, casings,
cabins, wall cladding, ceilings,
silencers, etc. Screens
installed between the noise source and
workplace. acoustic effect
screen is based on the education behind it
shadow areas where sound waves
penetrate only partially. Degree
penetration depends on the ratio
between screen sizes and wavelength:
the longer the wavelength, the less
given dimensions, the shadow area, the smaller
noise reduction. Silencers
noise apply
mainly to reduce the noise of various
aerodynamic installations and devices.
They separate
adsorption,
reactive and combined. Adsorption
mufflers containing sound-absorbing
material that absorb the incoming
sound energy, and reactive reflect
her back to the source. In combined
mufflers occurs as absorption,
as well as sound reflection. Method
noise emission direction changes.
It is used in design
installations with directional noise, consists
in the appropriate installation orientation
towards the workplace.
Rational
workshop planning.
When planning, noisy workshops should
be concentrated in one or two
places. If the business is located
in the city, then noisy workshops should
located in the interior.
If
noise level is not reduced within
norms, individual
protective equipment (headphones, headsets).
Control devices: - sound level meters; —
vibroacoustic complex - RFT, VSHV.
4 Vibration in residential environments
Vibration
- it
mechanical oscillations of elastic media.
According to the nature of contact with the body, they distinguish
local and general vibration. Allocate
low-frequency (8–16 Hz), mid-frequency
(16–64 Hz) and high frequency (64–1000 Hz)
vibration areas.
Vibration
refers to one of the physical
pollution of the human environment.
Influencing a living organism, mechanical
vibrations are converted into energy
biochemical and biophysical processes,
shaping the body's response.
fluctuations
in a dwelling can generate external
sources, such as underground and ground
transport, industrial enterprises.
Often the source can be
construction organizations: when driving
piles, when dismantling and breaking buildings, when
performing road works. Length
vibration impact zone is determined
its damping value. in dry ground,
for example, it is about 1
dB/m, and higher in water-saturated soils.
The problem of combating vibration has acquired
particular relevance in the construction
and operation in large cities
subways, which are often built
shallow laying method. lines
laid directly under residential
quarters, intense vibrations
are observed at a distance of 50–70 m in both
side of the line. Vibration generated
in the tunnel, transmitted through the ground
the foundation of buildings, exciting in them
fluctuations of various constructive
elements.
Research
distribution of vibrations on floors
buildings showed that in five-story buildings
vibration levels are declining
from the first to the fifth floor. In high-rise
buildings can, along with a decrease
vibrations on high floors are observed
and its increase due to resonant
phenomena.
Vibration
in a domestic environment can act
per person around the clock, calling
irritation, loss of sleep, disturbing rest.
Unlike noise, vibration is perceived
all organs and parts of the body.
Low frequency vibrations are perceived
otolith apparatus of the inner ear.
Sometimes the reaction of people to vibration
determined not so much by receptors
vibrations, how many secondary (visual,
auditory) receptors (rattling
crockery, swinging the chandelier).
subjective
perception of vibration depends on its
parameters and health status
person, fitness, individual
portability. On the perception of vibration
can be influenced by human activities.
At the same time, the vibration that interferes with a person
engaged in sedentary work will not
completely perceived by a person,
moving from place to place, i.e. than
the quieter the work, the more sensitive
to vibration man.
measure
vibration impact assessment
is the concept of "power of perception"
vibration by a person that binds
the magnitude of the oscillations, their frequency and
direction. There are three degrees
human response to vibration:
-
threshold
perception by a seated person
sinusoidal oscillations; -
occurrence
unpleasant sensations; -
limit
voluntarily transferred vibration in
within 20 minutes.
special
attention should be paid to the study of the phenomenon
resonance, both of the whole body and individual
parts and organs under vibration conditions.
It has been found that at frequencies above 2 Hz
a person behaves as an integral system.
For a seated person, the resonance is
in the range of 4–6 Hz. Other frequency band
resonance lies in the region of 17–30 Hz and
manifests itself in the system "head -
neck - shoulder
In this range, the amplitude
head vibrations can three times
exceed the amplitude of the swing of the shoulders.
Greatest
the number of complaints made by people aged
31–40 years old. Vibration intolerant people
suffering from cardiovascular and
nervous diseases.
For
regulation of the impact of vibration on
living organisms as the main
values accepted threshold
vibration sensations.
Limit values are given as multiples
values for this threshold. Allowed at night
one-time vibration sensation threshold,
day - twice.Vibration standards
given in the Sanitary Rules and Norms No.
1304–75. Vibration standards in residential buildings.
