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Unit B > B6 Ollie > Flashcards

B6 Ollie Flashcards

1
Q

Noise

A

Noise at WorkRegulations 2005:
Any audible sound
Oxford English Dictionary:
A sound, especially one that is loud or unpleasant or that causes disturbance
Sound:
Vibrations or pressure changes passing through a medium, usually air

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2
Q

Sound

A

Amlitude- Strength in which sound travels
Frequency - Number of wave fronts hitting the ear drum

Time

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3
Q

Sound Intensity and Decibels

A

Intensity is sound power per unit area
A measure of the flow of sound energy - units W/m2 Lowest value detected by human ear is 10-12 W/m2 Highest likely to be encountered is 1 W/m2
Very large range so Decibel (dB) used for convenience Logarithmic scale
Usually express ed as sound pressure level

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4
Q

Decibel Scale

A

Threshold of pain -
130 Noisy factory - 90 Busy traffic - 70

Normal conversation -60 Soft whisper - 20
Threshold of hearing - 0

Logarithmic scale, so increase of 3 dB means doubling of sound intensity

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5
Q

Adding Decibels

A

If adding similar values , add 3dB
e.g. 90dB + 90 dB = 93dB
If adding dissimilar values , use graph or table

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6
Q

Frequency

A

Pitch of note
Sounds us ally a mixture of frequencies
Human hearing range given as 20Hz to 20KHz
Frequencies often divided into octave bands ,
represented by central value
Frequency important in control, and selection of hearing defenders

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7
Q

Frequency-Octave bands

A

Graph- dB vertical and Hertz (Hz) Horizontal

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8
Q

A-Weighting

A

Tones of the same pressure level do not sound equally loud to the ear, nor do they have the same potential for causing hearing loss
High frequencies sound louder and are more likely to cause damage
Low frequencies sound quieter and are less likely to cause damage
A- weighting compensates for this difference After A-weighting is adopted - dB(A)

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9
Q

C-Weighting

A

A-weighting is not appropriate at high noise levels
Ear becomes better at hearing high/low frequencies Almost linear response
Used for peak values -dB(C)

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10
Q

Noise Dose

A

Noise measurements usually averaged over a time period
Known as Leq:
L can be any length of time
Control of Noise at Work Regulations refer to Daily noise exposure:
Averaged over 8 hour period
Known as daily noise exposure or LEP,d
Also make reference to peak values

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11
Q

Mechanism of Hearing

A

Vibrations directed by pinna into auditory canal
Eardrum vibrates
Vibrations carried across middle ear by ossicles to cochlea
Vibrations pass through fluid in cochlea in inner ear Detected by sensory hairs (stereocilia)
Conveyed to brain by auditory nerve

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12
Q

Noise-AdverseHealth Effects

A

Nuisance and stress
Tinnitus
Noise induced hearing loss (NIHL)
Temporary threshold shift - reversible damage (auditory fatigue)
Permanent threshold shift - failure of her cells to
respond to frequencies
Acoustic trauma
TTS & PTS (NIHL) generally occurs in the 4000hz octave band- 4K dip

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13
Q

Acoustic Shock

A

Sudden, unexpected loud sound through headset May be below Action Values
No loss of hearing

Symptoms:
Early: tinnitus , dizziness , nausea
Intermediate: headaches , fatigue, anxiety
Late: hypersensitivity, anxiety returning to telephone work

Controls:
Protection devices
Reduce background noise
Prompt repair of equipment
Manual control of voice levels
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14
Q

Audiometry - Basic Principles

A

Routine health surveillance
Health surveillance required if risk assessment identifies risk to health
Guidance suggests this is regular exposure above upper exposure action value
Shall include test of hearing –audiometry
Used as base line assessment
Also implications in Civil Law

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15
Q

Audiometry - Method

A

Details given in s tandard (EN26189:1991)
Quiet environment
No significant noise for 16 hours previously
Pure tones played - subject presses button if heard Software produces graph (audiogram)

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16
Q

Audiometry - Action to be Taken

A

Category& Action
1: Acceptable:
No action required

2: Mild hearing impairment:
Formal notification
Reinforcement of training and importance of controls Good practice to issue copy of audiogram

3:Poor hearing:
Referral to medical practitioner

4: Rapid hearing loss
Referral to medical practitioner

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17
Q

Control of Noise at Work Regulations (CNWR)2005-Regulation 4 & 5

A

Reg.4:
Exposure action values and exposure limit values

Reg.5:
Assessment to be carried out where exposure likely to reach lower exposure action value (80 dB(A))

To cover:
Level, type, duration of exposure
Manufacturers information
Availability of alternative equipment 
Results of health surveillance 
Availability of PPE
Recorded and reviewed
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18
Q

CNWR -Action Values

A

Lower Exposure Action Value - 80 dB ( A )
LEP,d / Peak 135 dB ( C ) :

Make PPE available
Provide information and training Assessment Upper Exposure Action Value -85dB(A)
LEP,d/Peak137 dB(C):

Reduce ALARP by means other than PPE
Hearing Protection Zones
Health surveillance (audiometry)

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19
Q

CNWR - Limit Values

A

Upper Exposure Limit Value - 87 dB ( A ) LEP , d / Peak 140 dB ( C ) :
Not to be exceeded

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20
Q

CNWR - Limit Values Exceeded

A

Exposure is not permitted above exposure limit value (87dB(A))

If exposure does occur, employer must reduce
exposure to noise to below the exposure limit value
Identify the reason for that exposure limit value being exceeded

Modify the organisational and technical measures to prevent it being exceeded again

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21
Q

CNWR -Regulation 7

A

Hearing protection:
To be made available at or above lower exposure action value
Must be worn above upper exposure action value (if cannot be controlled by other means )
Hearing Protection Zones:
Designated and signage displayed
Employer to maintain PPE and ensure use SFARP (Reg 8)

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22
Q

CNWR -Regulation 9 & 10

A

Reg.9 -Health surveillance:
Where the risk assessment indicates that there is a risk to health Risk to health:
If there is regular exposure above the upper exposure action value
Must include a hearing test (audiometry)
If hearing damage is identified then the employer must refer the individual to a medical practitioner.
Reg. 10:
Employer to provide information, instruction and training where lower exposure action value is reached

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23
Q

CNWR -Employees Duties

A

To comply with the employers arrangements for controlling noise

To use hearing protectors and noise control equipment

To take care of such equipment, and to report any defects (all Reg 8)

To co-operate with employer and attend hearing tests (Reg 9)

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24
Q

Noise Measurement - Basic Principles

A

Sound Level Meter:

Simple measures dB or dB(A) at a moment in time Integrating if measures Leq

Leq - equivalent continuous noise level

Need to measure A-weighted Leq (LAeq)

Need C-weighting for peak levels

Need to be calibrated each time they are used

25
Q

Noise Measurement-Classes of Device

A

Lower the class of SLM, higher the quality
Class 0-Research
Clas s 1 - Laboratory/Field
Class 2 -General Field
Class 3-Non integrating
Calibrators also different classes
Selection depends on objectives of survey
Increasing accuracy and response from
Class 3 toClass 0
Class 1 or 2 for occupational safety measurements

26
Q

Noise Measurement - Personal Dose Meters & Frequency Analysers

A

Personal dose meters:
Worn by person exposed in hearing zone
Measures actual dose for referenced time period
Frequency analysers:
Measure sound pressure levels at particular frequencies
Required for accurate assessment of hearing defenders
Combination of above and accessories
e.g. storage of data, print outs , software

27
Q

Work place Noise Survey

A

Planning:
Objectives and scope

Information sources:
Previous assessments Employees
Manufacturers information Complaints
Selection of measuring equipment including calibrators Battery check
Number of employees exposed/duration
Areas to be surveyed
Recording of data
Route
Safety issues/risk assessment
28
Q

The Ready Reckoner - Estimate (L108)

A

Estimate of noise exposure:
Try this :
1) 30mins spent working on a grinding machine - manufacturers info says 95dB

2) 3hours working in yard with vehicles - check
suggests 85dB

3)1.5hours in office-check suggests 80dB

4 ) 2 hours back in yard at 85d B

29
Q

Estimating LEPd - Static Measurements

A

Static measurements taken at operating positions at each machine
Static measurements taken during normal operation
Sound measured as LAeq
Use integrating SLM
Note the time operator spends at each machine
Calculate using points system/HSE s preadsheet
Assess or assume insignificant exposure during breaks

30
Q

Noise Propagation

A

Walls-Screens–steel Cladding

31
Q

Effect of Distance - Inverse Square Law

A

Inverse square law:
Refers to decrease in noise energy (and other energy forms ) as it moves away from a point source
Energy/intensity is proportional to 1/d2* (d = dis tance)
At 1 unit distance = 1/1 2* = 1
At 2 units distance=1/22=1/4
At 3 units distance=1/32=1/9
Note: 2*denotes squared

32
Q

Effect of Distance - Doubling Distance

A

Doubling of distance means a reduction of noise of 6 dB

33
Q

Controlling Noise-General Principles

A

Eliminate at source, or control so far as is reasonably practicable at source (e.g. by relocation, redesign and maintenance)
Control along the transmission path (e.g. by using
isolation, barriers and enclosures)
Control exposure at the receiver (e.g. by enclosures , acoustic havens , hearing protection zones and PPE, limiting exposure time, audiometry)

34
Q

Controlling Noise-Methods (1)

A

Engineering controls
Selection of equipment (presses instead of hammers ) Location of pipe-work and ducting
Reduce operation speeds
Distance/orientation
Maintenance (balancing, sharpening, tightening)

35
Q

Controlling Noise-Methods (2)

A

Enclosure (noise enclosures ) Isolation(noise havens,springs to absorb energy)
Silencers (air movements /absorptive reactive)
Lagging
Damping (pads,stiffening)
Screens
Absorption
PPE

36
Q

Acoustic Enclosure - Design (1)

A 
Keeps noise in
Heavy outer wall (plasterboard and brickwork) 
Inner lining of acoustically absorbent material 
Absorbent covered in protective mesh
Flexible pipes to form vibration breaks 
Services in through ground
Inspection door double/triple glazed
Access panels for maintenance
37
Q

Acoustic Enclosure - Design (2)

A 
Access doors air tight
Any joints to outside sealed
Motors on dampers
Machines covered in enclosures
Avoid contact between equipment and walls 
Sound absorbent material on floors 
Silencers on any ventilation exits Self-closing doors
Exterior controls
38
Q

Acoustic Haven

A 
Keep noise out
Air conditioned/lighting/thermal comfort/works stations Viewing windows
Emergency response (fire alarms etc)
Above workplace for better view
External surface reflective
Internal acoustic absorbent
Internal walls cleanable
Isolated from floor and ceiling
Double/triple glazed
Air supply through lagged pipework
39
Q

Hearing Protection - Basics Principles (1)

A 
Selection is critical
Matched to noise characteristics 
Will only be effective when used Types and specifications: 
Ear defenders
Semi-inserts
Earplugs
Active hearing protection
40
Q

Hearing Protection - Basics Principles (2)

A

Mean attenuation values at frequency bands
63-8000 Hz
Subjective tes t - 16 test subjects
Standard deviation values for each (+/-84%)
Assumed protection values at each frequency ( = mean – one standard deviation)
HML (high, medium, low) values SNR (single number rating)

41
Q

Hearing Protection - Selection

A

Use HML (apply formula)
Use SNR
Octave band frequency

42
Q

Hearing Protection - Single Number Rating (SNR)

A

Simple guide to hearing protection required:
Noise Level dB(A)&SNR Required

85-90-20or less

90-95- 20-30

95-100 - 25-35

100-105- 30 or more

43
Q

Vibration - Basic Principles

A

Oscillating movement of a fixed point due to applied energy

44
Q

Vibration - Basic Terms

A

Displacement (amplitude) – maximum distance moved from the point of oscillation

Frequency – number of complete oscillations per
second (Hertz )

Velocity – speed of the oscillating object at a fixed point in time (m/s ) Acceleration – maximum rate of increase in s peed (m/s 2 )

Magnitude – Vibration at Work Regulations 2005= acceleration

45
Q

Measurement of Vibration

A

Accelerometer
Average (root-mean-s quare) of acceleration in three planes
Weighting given to most harmful frequencies (8-20Hz) Expressed as A(8)-daily exposure

46
Q

Hand Arm Vibration Syndrome (HAVS)

A

Impaired circulation to fingers - blanching (white finger) Numbness in fingers , reduced sensitivity, tingling
Loss of dexterity
Loss of grip strength
Pain (especially in cold weather)
Infection/gangrene
Carpal Tunnel Syndrome and associated symptoms

47
Q

Whole Body Vibration

A 
Range of health effects
Back pain
Nausea
Gastrointestinal upsets
General feeling of discomfort, including headaches 
Loss of equilibrium (balance)
Abdominal pain
48
Q

Factors Contributing to Risk

A 
Damage depends on:
Vibration magnitude
Vibration frequency
Duration of exposure
Individual susceptibility (diabetics /smokers more at risk) 
External temperature
Tightness of grip
49
Q

Control of Vibration at Work Regulations (CVWR) 2005- EAVs & ELVs

A

Exposure limit values and exposure action values :

Hand-armvibration:
EAV 2.5ms -2 A(8)
ELV 5.0 ms -2 A(8)

Whole body vibration:
EAV 0.5ms -2 A(8)
ELV 1.15ms -2 A(8)

A(8) vibration dose averaged over an 8-hour shift

50
Q

CVWR - ELV

A

Must not be exceeded
If exceeded then:
Reduce exposure to vibration to below the limit value
Identify the reason for that limit being exceeded
Modify the measures taken to ensure it does not happen again

51
Q

CVWR - ELV

A

Provide appropriate health surveillance
(Regulation 7)

Provide adequate information, instruction and training (Regulation 8).

52
Q

CVWR -Risk Assessment

A

Reg 5:
Risk assessment required if employees are exposed to risk due to vibration

Assessmentto consider:
The frequency and magnitude of vibration
The health effects of exposure to vibration
Any information provided by the manufacturers of work equipment
The availability of replacement equipment designed to reduce exposure to vibration
Specific working conditions such as low temperatures appropriate information obtained from health surveillance

53
Q

Estimating Daily Exposure

A

Graph

Points system

54
Q

Hand Arm Vibration - Controls

A 
Automation
Change of work method
Modify/use alternative equipment
Purchasing policy
Maintenance
Monitor exposure and enforce limits 
Job rotation 
Instruction and training
Health surveillance
PPE - gloves to keep hands warm
Warm temperatures
55
Q

Hand Arm Vibration - Health Surveillance

A

Tier 1 - A short questionnaire used for new workers
Tier 2 - A short questionnaire for employees already exposed
Tier 3 - This involves a HAVS health assessment by a qualified person, if the assessments hows that the employee has HAVS, Tier 4 will apply
Tier 4 - Formal diagnosis by occupational health
physician
Tier 5 - Optional: referral for further tests

56
Q

Hand Arm Vibration - Tier 3/4 Assessment

A 
Grip strength
Muscular dexterity
Vascular
Finger rewarming after cold provocation
 Finger systolic blood pressure 
Sensorineural
Vibrotactile perception threshold 
Thermal perception threshold
57
Q

Hand Arm Vibration - Stockholm Workshop Scales

(Sensorineural)

A

Stage -Description:
0 SN - Vibration exposed & no symptoms
1 SN - Intermittent numbness with or without tingling
2 SN - Intermittent or persistent numbness , reduced
sensory perception
3 SN - Intermittent or persistent numbness , reduced tactile discrimination and/or manipulative dexterity

58
Q

Hand Arm Vibration - Stockholm Works hop Scales

(Vascular)

A

Stage -Grade -Description:
0 - No grade - No attacks

1V - Mild - Occasional attacks affecting tips of one or more fingers

2V-Moderate-Occasional attacks affecting distal and middle(rarely also proximal) phalanges of one or more fingers

3V - Severe - Frequent attacks affecting all phalanges of most fingers

4V-Very severe-As in stage 3 with trophic skin changes in the fingertips

59
Q

Whole Body Vibration - Controls

A

As for HAVS e.g. maintenance/automation etc
Specific examples:
Drive vehicles more slowly
Ergonomic design of vehicle cabs
Mount seats on springs or compression pads / provide cushions Provide rubber mats for standing tasks

Unit B (20 decks)

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