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OCCUPTIONAL VIBRATION Presentation Transcript
1.OCCUPTIONAL VIBRATION
2.Introduction
TYPE
SYPMTOMS
MEASUREMENT
CONTROL
Case Studies
TYPE
SYPMTOMS
MEASUREMENT
CONTROL
Case Studies
3.VIBRATIONS
An object moving back and forth, up and down and side to side rapidly
Frequency- number of vibrating movements in a given period of time or cycles/s measured in Hz
Amplitude- intensity or magnitude of vibration, maximum distance an object moves from central point, measured in m
An object moving back and forth, up and down and side to side rapidly
Frequency- number of vibrating movements in a given period of time or cycles/s measured in Hz
Amplitude- intensity or magnitude of vibration, maximum distance an object moves from central point, measured in m
4.Two Types
1 Whole body vibration or head to toe exposure -affects such employees as truck, bus, heavy equipment, farm vehicle, forklift and overhead-crane operators
2 Hand-arm vibration or localized vibration exposure, mainly, but not exclusively, affecting employees
1 Whole body vibration or head to toe exposure -affects such employees as truck, bus, heavy equipment, farm vehicle, forklift and overhead-crane operators
2 Hand-arm vibration or localized vibration exposure, mainly, but not exclusively, affecting employees
who use all manner of vibrating pneumatic,
electrical, hydraulic, and gasoline-powered hand tools
5.WBV and HAV
a) Both occurring simultaneously-E.g. motorcycling or mountain bike
b)Different medical effects of HAV and WBV as
are their vibration exposure so discussed differently
c) Share a common physics
d) Do not share a common physiology
e) They share the same safety and health effects.
6.Hand arm vibration
Daily use of vibrating pneumatic hand tools by workers in the quarrying, cutting, and carving of oolitic limestone in Indiana termed this condition
“Raynaud’s phenomenon of occupational origin” name would be changed to
“vibration white ?nger” or “dead hand” disease
?nally this condition became known as ”hand-arm vibration syndrome”
7. Major Symptoms
Are initially characterized by tingling and/or
numbness in the ?ngers
With continuous vibration exposure the appearance of a single “white” or blanched fingertip occurs.
Usually, but not always, in the presence of cold
a) Both occurring simultaneously-E.g. motorcycling or mountain bike
b)Different medical effects of HAV and WBV as
are their vibration exposure so discussed differently
c) Share a common physics
d) Do not share a common physiology
e) They share the same safety and health effects.
6.Hand arm vibration
Daily use of vibrating pneumatic hand tools by workers in the quarrying, cutting, and carving of oolitic limestone in Indiana termed this condition
“Raynaud’s phenomenon of occupational origin” name would be changed to
“vibration white ?nger” or “dead hand” disease
?nally this condition became known as ”hand-arm vibration syndrome”
7. Major Symptoms
Are initially characterized by tingling and/or
numbness in the ?ngers
With continuous vibration exposure the appearance of a single “white” or blanched fingertip occurs.
Usually, but not always, in the presence of cold
8.In the later stages of HAVS, attacks can and do occur in all seasons as well as on and off the job
HAVS interferes in both the patient’s work and nonworking lives, vibration, cold and nicotine from smoking is particularly deadly, since all three tend to act as vasoconstrictors and thus help “close down” blood vessels
HAVS interferes in both the patient’s work and nonworking lives, vibration, cold and nicotine from smoking is particularly deadly, since all three tend to act as vasoconstrictors and thus help “close down” blood vessels
9.Extreme conditions, the loss of blood supply to the fingers can lead to gangrene, which may require finger amputation. Thus HAVS can quickly become a serious occupational disease
10.WBV exposure has been causally linked, but not limited to, severe low-back pain (lumbar spine) and degeneration, moisture loss, buckling
poor vehicle seating, awkward postures, and manual cargo handling in addition to WBV exposure tend to exacerbate low-back pain miser
poor vehicle seating, awkward postures, and manual cargo handling in addition to WBV exposure tend to exacerbate low-back pain miser
11.Motion is described by both a magnitude and
intensity (i.e., acceleration or velocity or displacement)and a
direction in which the motion moves
Vibration at any given point is de?ned by six vectors: three mutually perpendicular “linear” motions that move in a line (i.e., front-to-back, up-down, side-to-side)and three rotational vectors (i.e., pitch, yaw, roll)
Vibration at any given point is de?ned by six vectors: three mutually perpendicular “linear” motions that move in a line (i.e., front-to-back, up-down, side-to-side)and three rotational vectors (i.e., pitch, yaw, roll)
12.BASICS: VIBRATION MEASUREMENTS
For occupational vibration, rotational motions are not measured; only the three (triaxial) linear axes are simulta-neously measured.
For HAV, vibration is measured from tool handles, where the worker grasps the tool, while for WBV, it is measured from the top of seat cushion where a vehicle driver sits.
The measure of vibration intensity is usually acceleration or, more precisely, a form of average acceleration known as
rms, or root-mean-squared, acceleration.
This is measured separately and simultaneously for each of the three mutually perpendicular axes
For occupational vibration, rotational motions are not measured; only the three (triaxial) linear axes are simulta-neously measured.
For HAV, vibration is measured from tool handles, where the worker grasps the tool, while for WBV, it is measured from the top of seat cushion where a vehicle driver sits.
The measure of vibration intensity is usually acceleration or, more precisely, a form of average acceleration known as
rms, or root-mean-squared, acceleration.
This is measured separately and simultaneously for each of the three mutually perpendicular axes
13.WHOLE BODY MEASUREMENTS
1 a hard-rubber seat pad/disc that contains the triaxial accelerometers is attached to the seat of the operator, commonly using duct tape
2 frequency below 1 Hz measurements initially were made using devices such as piezoresistive accelerometers or
1 a hard-rubber seat pad/disc that contains the triaxial accelerometers is attached to the seat of the operator, commonly using duct tape
2 frequency below 1 Hz measurements initially were made using devices such as piezoresistive accelerometers or
capacitive accelerometers
14.WHOLE BODY VIBRATION MEASUREMENTS
During measurements, the seat must be occupied so that the seat pad re?ects the accelerations actually being transmitted to the body.
Data collection needs to be a minimum of 2 to 5 min so that the processed values obtained have statistical signi?cance
During measurements, the seat must be occupied so that the seat pad re?ects the accelerations actually being transmitted to the body.
Data collection needs to be a minimum of 2 to 5 min so that the processed values obtained have statistical signi?cance
15.HAND ARM VIBRATION MEASUREMENTS
Triaxial accelerometers must be mounted in close proximity to the hands during functional use of the tool
Transducers need to be mounted as rigidly as possible to the tool to insure the full transmission of tool vibration to the transducer
The time of measurement needs to exceed 90 sec of continuous vibration to provide statistical signi?cance
Triaxial accelerometers must be mounted in close proximity to the hands during functional use of the tool
Transducers need to be mounted as rigidly as possible to the tool to insure the full transmission of tool vibration to the transducer
The time of measurement needs to exceed 90 sec of continuous vibration to provide statistical signi?cance
16.1: Identify Activities Causing Vibration Exposure
To do so, hold discussions with workers andsupervisors, and observe work activities to develop an understanding of:
? work operations
? tasks performed
? tools and equipment used
? vehicles used
To do so, hold discussions with workers andsupervisors, and observe work activities to develop an understanding of:
? work operations
? tasks performed
? tools and equipment used
? vehicles used
17.Estimate the Duration of Exposure
determine the typical frequency (how often and) duration of vibration exposure
record how often and for how long equipment or tools are used
make estimates through discussions with workers and supervisors , reviewing work activity records , and direct observation
determine the typical frequency (how often and) duration of vibration exposure
record how often and for how long equipment or tools are used
make estimates through discussions with workers and supervisors , reviewing work activity records , and direct observation
18.Use Published Data to Determine Potential Exposure Intensity
researchers have measured the HAV exposures for a variety of hand-held and hand-guided tools and WBV exposures associated with the operation of different type of mobile andstationary equipment
vibration levels fall within a range of values
exposures the highest potential vibration intensity in the published range should be used unless it is certain that the vibration intensity of the tool in question is actually lower
19.Compare the Estimated Exposure to Recommended Maximum Permissible Exposure Limits
compare estimated exposure duration and potential exposure intensity to
researchers have measured the HAV exposures for a variety of hand-held and hand-guided tools and WBV exposures associated with the operation of different type of mobile andstationary equipment
vibration levels fall within a range of values
exposures the highest potential vibration intensity in the published range should be used unless it is certain that the vibration intensity of the tool in question is actually lower
19.Compare the Estimated Exposure to Recommended Maximum Permissible Exposure Limits
compare estimated exposure duration and potential exposure intensity to
maximum permissible vibration exposure limits,
such as those suggested in the ACGIH, CEN and ISO standards
if estimated vibration exposure duration and intensity are higher than the suggested limits, then the actual vibration
exposure could be unacceptably high
if estimated vibration exposure duration and intensity are higher than the suggested limits, then the actual vibration
exposure could be unacceptably high
20.ISO International Organization for Standardization
ACGIH
American Conference of
Governmental Industrial Hygienists
CEN
European Committee for Standardization
ACGIH
American Conference of
Governmental Industrial Hygienists
CEN
European Committee for Standardization
21.Implement Simple Vibration Controls
If vibration exposures might be too high, then steps should be taken to reduce exposures
reduce the duration of time that the worker performs the work
But reducing the amount of time the worker is exposed to vibration
is not always possible
workers may be under pressure to complete their work
In these cases, other vibration reduction methods should be explored.
Table identifies a variety of simple vibration reduction methods that should be considered where assessment identifies the
potential for excessive vibration exposure.
If vibration exposures might be too high, then steps should be taken to reduce exposures
reduce the duration of time that the worker performs the work
But reducing the amount of time the worker is exposed to vibration
is not always possible
workers may be under pressure to complete their work
In these cases, other vibration reduction methods should be explored.
Table identifies a variety of simple vibration reduction methods that should be considered where assessment identifies the
potential for excessive vibration exposure.
22.Get Expert Assistance if Necessary
vibration exposure assessment method described above may lead to the conclusion that exposure could be close to being, or is likely to be, excessive or cannot be determined
in such cases, expert assistance should be sought to either conduct measurements of vibration intensity to more conclusively determine the potential for adverse health effects; or recommend vibration-reducing control measures
vibration exposure assessment method described above may lead to the conclusion that exposure could be close to being, or is likely to be, excessive or cannot be determined
in such cases, expert assistance should be sought to either conduct measurements of vibration intensity to more conclusively determine the potential for adverse health effects; or recommend vibration-reducing control measures
23. Identify the Vibration Sources: Crews of workers use chain-saws every day to trim tree branches that grow too close to power lines. Each crew consists of two workers, who share all duties. The only hand-held power tool that they use in their work is a chain saw.
24.Identify the Vibration Sources: Crews of workers use chain-saws every day to trim tree branches that grow too close to power lines. Each crew consists of two workers, who share all duties. The only hand-held power tool that they use in their work is a chain saw.
25.Estimate the Exposure Duration: after speaking with the workers, and observing their work operations, and it was found that during a typical day, each worker does the following activities for the time indicated
26.So, assuming that the only activity resulting in hand-arm vibration is operating the chain saw
then the total duration of hand-arm vibration exposure is 3.5 hours
then the total duration of hand-arm vibration exposure is 3.5 hours
27.Use Published Data to Estimate Vibration Exposure Intensity:
we see that chain saws have a wide range of vibration intensities – anywhere from as low as 1 m/s2 to as high as 12 m/s2.
Figure also shows that about 50% of all chain saw models fall in the range of about 5 m/s2 to 7 m/s2.
we can do our exposure estimation in a variety of ways, using the lowest, middle, or highest vibration intensities. To be most cautious, we should use the highest vibration intensity, 12 m/s2.
28.4 Compare Exposure Levels to Maximum Permissible Exposure Limits:
we have found that workers operating chain saws may be exposed for 3.5 hours/ day to a vibration intensity as high as 12 m/s2
we can now compare this to recommended maximum permissible exposure limits
we see that chain saws have a wide range of vibration intensities – anywhere from as low as 1 m/s2 to as high as 12 m/s2.
Figure also shows that about 50% of all chain saw models fall in the range of about 5 m/s2 to 7 m/s2.
we can do our exposure estimation in a variety of ways, using the lowest, middle, or highest vibration intensities. To be most cautious, we should use the highest vibration intensity, 12 m/s2.
28.4 Compare Exposure Levels to Maximum Permissible Exposure Limits:
we have found that workers operating chain saws may be exposed for 3.5 hours/ day to a vibration intensity as high as 12 m/s2
we can now compare this to recommended maximum permissible exposure limits
29.Should this Vibration Exposure Be Considered Acceptable?:
Here, the actual vibration intensity of the chain saw is unknown, and there are large differences between the
potentially lowest and highest vibration intensities. In a case such as this, it is best to either
obtain information on the actual vibration levels from the chain saw manufacturer or consult
an expert to conduct hand-arm vibration exposure measurements.
Here, the actual vibration intensity of the chain saw is unknown, and there are large differences between the
potentially lowest and highest vibration intensities. In a case such as this, it is best to either
obtain information on the actual vibration levels from the chain saw manufacturer or consult
an expert to conduct hand-arm vibration exposure measurements.
30.Estimating WBV Exposure from Various Construction EquipmentS
1 Identify the Vibration Sources: A construction company has backhoes and small
bulldozers. It is determined that on a typical day, an operator will operate both a backhoe and
a bulldozer. These pieces of equipment are the only sources of whole body vibration exposure.
1 Identify the Vibration Sources: A construction company has backhoes and small
bulldozers. It is determined that on a typical day, an operator will operate both a backhoe and
a bulldozer. These pieces of equipment are the only sources of whole body vibration exposure.
31.Estimate the Exposure Duration:
You have spoken with the operators, observed their work, and have found that over the course of a typical day, each operator does the following activities for the times
So, there are two activities resulting in whole body vibration: backhoe operation (for 3 hours), and bulldozer operation (for 3 hours).
You have spoken with the operators, observed their work, and have found that over the course of a typical day, each operator does the following activities for the times
So, there are two activities resulting in whole body vibration: backhoe operation (for 3 hours), and bulldozer operation (for 3 hours).
32.Use Published Data to Estimate Vibration Exposure Intensity:
Using Figure we can see that:
?the backhoe can produce whole body vibration exposure of about 1.05 m/s2
?the small bulldozer can produce whole body vibration exposure of about 1.1 m/s2
These are fairly similar vibration intensities for both types of equipment, so for simplicity we
can say that the operator is exposed to whole body vibration of approximately 1 m/s2 for 6 hours.
33.Compare Exposure Levels to Maximum Permissible Exposure Limits:
To this point, we have concluded that the operators may be exposed for 6 hours per day to a vibration
intensity of 1 m/s2. We can now compare this to recommended maximum permissible exposure limits.
Table shows CEN vibration exposure limits for whole body vibration By CEN recommendations, a worker’s daily exposure to whole body vibration (i.e. exposure
over an 8 hour day) should not exceed 1.15 m/s2 .
34.Should this Vibration Exposure Be Considered Acceptable?
In this example, if the actual
vibration intensity is about 1 m/s2 for 6 hours, then the exposure is below the CEN daily
exposure limit, and the vibration exposure can be considered acceptable.
Using Figure we can see that:
?the backhoe can produce whole body vibration exposure of about 1.05 m/s2
?the small bulldozer can produce whole body vibration exposure of about 1.1 m/s2
These are fairly similar vibration intensities for both types of equipment, so for simplicity we
can say that the operator is exposed to whole body vibration of approximately 1 m/s2 for 6 hours.
33.Compare Exposure Levels to Maximum Permissible Exposure Limits:
To this point, we have concluded that the operators may be exposed for 6 hours per day to a vibration
intensity of 1 m/s2. We can now compare this to recommended maximum permissible exposure limits.
Table shows CEN vibration exposure limits for whole body vibration By CEN recommendations, a worker’s daily exposure to whole body vibration (i.e. exposure
over an 8 hour day) should not exceed 1.15 m/s2 .
34.Should this Vibration Exposure Be Considered Acceptable?
In this example, if the actual
vibration intensity is about 1 m/s2 for 6 hours, then the exposure is below the CEN daily
exposure limit, and the vibration exposure can be considered acceptable.
35.Handbook of human factors and ergonomics by Neville Stanton, CRC press, Chapter 73
Google images
http://www.machinemonitoring.co.uk/services/?c=80-HandArm-Vibration
Work Safe Alberta, best practices- vibration at the work site, February 2010
Google images
http://www.machinemonitoring.co.uk/services/?c=80-HandArm-Vibration
Work Safe Alberta, best practices- vibration at the work site, February 2010
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