C6.3 Protective measures Flashcards

1
Q

Guarding requirements

A
suitable
good construction
in good repair
efficient working order
no additional risk
not easily disabled / bypassed
at a distance from danger zone
not unduly restrictive
permit maintenance
prevent contact
secured to machine
protect so that objects cannot fall onto moving parts
introduce no new hazards
do not interfere with the work
allow safe lubrication
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2
Q

PUWER Reg 11 hierarchy of guarding

A

Fixed or enclosed guards
Interlocking guards or auto devices
Appliances, eg push sticks
Training, info, instruction, supervision

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3
Q

Types of guards

A

Fixed
Interlock
Automatic
Trip

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4
Q

Fixed enclosed guards

A

denies access to danger at all times
fixed to machine
need tool to remove
openings must not lead to danger

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5
Q

Adjustable guard

A

adjustable bars to allow workpiece only to enter

adjusts to allow variety of workpieces

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6
Q

self adjusting guard

A

barrier moves dependent on size of workpiece

eg circular saw

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7
Q

Two hand control

A

both hands needed on controls to operate
constant correct pressure
hands in a safe location

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8
Q

Interlocked guard

A
machine cannot operate when access available to danger zone
guard closed = machine can operate
operates by limit switches
fail to safe
electrical
mechanical
hydraulic
pneumatic
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9
Q

automatic guard

A

sweeps danger zone clear

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10
Q

photoelectric devices

A

light curtain beam

machine stops if broken

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11
Q

capacitance field

A

machine stops if electric field broken

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12
Q

pullback devices

A

cables connected to operators hands
used with machine with stroke action
access allowed when device is up
hands pulled back as device descends

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13
Q

restraint device

A

hands attached to cables that restrain where hands can go

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14
Q

trip wire

A

pull wire to stop machine

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15
Q

gates

A

machine only operates if gate closed

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16
Q

robots

A

repetitive processes
prevent injury from repetition
use where unsafe / hazardous / unpleasant tasks

17
Q

protective shields

A

protection from flying particles / substances

18
Q

holding tools

A

used to place / remove items in danger zone

use as an additional control, not in place of

19
Q

guard considerations

A

prevent any part of body reaching danger zone
any opening at distance to prevent reaching danger zone
ability to withstand force of ejection
protect against hazards identified
weight / size of guard
compatible with material being processed
resistant to possible contaminants

20
Q

fixed distance guards

A

does not completely cover danger zone but places it out of reach

21
Q

barrier considerations

A

height and distance to prevent reaching danger zone

1.8 metres for perimeter fencing

22
Q

interlocks - sensing devices

A

rotating sensing
light beam
proximity device
position switch

23
Q

interlocks - timing devices

A

mechanical, electric, electronic clock
delay relay
sequence valve
threaded bolt

24
Q

interlock failure mechanisms

A
failure / interruption of power supply
wiring malfunction
earthing fault
cross connection
electrical interference
disconnection of hose / pipe
mechanical failure
brake failure
25
interlock failure controls
dual control system with / without cross monitoring
26
normally open limit switch
spring keeps contact open easy to defeat broken spring = switch is on can jam in on position
27
normally closed limit switch
``` spring closes contact difficult to defeat fails to safe wear / misalignment = fail to danger switch active if guard removed = danger ```
28
positive & negative limit switch in series
very difficult to defeat rigorous maintenance needed monitor switches with warning lights
29
interlock switch types
``` cam operated switch tongue operated switch captive key switch trapped key proximity switch magnetic switch diode link manually operated delay bolt solenoid operated shot bolt ```
30
cam operated position switch
movement of guard from safe position causes switch plunger to be depressed and trip the controls
31
magnetic switch
actuating magnet attached to guard | easily defeated
32
captive key system
guard has to be closed before key can be put in lock
33
trapped key system
removable key trapped in lock | when guard closed, key can be removed
34
pressure sensitive mat
pressure sensors - equipment operates when activated can be damaged mat of suitable dimension that person cannot reach danger zone when standing on mat
35
reasons why light beam cannot be used
``` slow machine response time poor brake design variable machine speed machine cannot stop part cycle machine is part of production line stored energy machine can eject parts ``` CAN be used in conjunction with other means to control risks
36
mechanical restraints
mechanical restraint to dangerous parts to prevent it moving | relies on strength of restraint
37
jigs
used to hold / move workpiece keeping body away from danger zone used in addition to guards
38
push sticks
used to feed timber into circular saws | used to push food into food processing machine