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Control measures for reducing risks from machinery hazards (Hierarchy of…
Control measures for reducing risks from machinery hazards (Hierarchy of controls 1-10)
Prevention of access to dangerous parts of machinery (PUWER Regulation 11)
If machinery could cause foreseeable injury, access to it should be prevented. Control measures should prevent access to dangerous parts
1. Fixed enclosed guards
Principles
Must be used whenever practicable
Physical barrier with no moving parts
Not connected to the machine controls
Attached to a machine & requires a tool to remove
Advantages
Creates a physical barrier with no moving parts
Has no moving parts so is more reliable
Needs a special tool to remove it
Disadvantages
Machine can become dangerous if guard is removed
Total enclosure means visual inspection more difficult
If enclosed, heat may increase risk of fire
2. Interlocking guards
Principles
Linked to the machine power supply
Machine cannot operate until the guard is closed
Machine will stop if the guard is opened
Advantages
Allows access to the machine where needed
Linked to controls; if opened during operation, machine will stop
Disadvantages
If interlock is a gate, person can open, enter, and close gate behind them (someone else could reactivate the machine)
Dangerous part of the machine will not stop immediately once guard is opened
3. Automatic guards
Principles
Operates automatically as machine goes through its cycle
In some cases, physically moves the operator away from danger zone
Advantages
Part of the normal machine cycle
Does not rely on human intervention to activate
Disadvantages
If interlock is a gate, person can open, enter, and close gate behind them (someone else could reactivate the machine)
Dangerous part of machine will not stop immediately once guard is opened
4. Self-adjusting guards
Principles
Fixed, but can be moved to a range of positions when required
Guard closes itself around the dangerous part (automatically or manually) as an integral part of the machine operation
Advantages
Closes over the dangerous parts to provide protection to operator
Does not require operator to set in position
Disadvantages
May obscure visibility during use
Does not completely prevent access to the dangerous part
4. Adjustable guards
Principles
Fixed, but can be moved to a range of positions when required
When adjusted remains in that position
Advantages
Cab be adjusted by operator where neccessary
Protects operator where size or position of dangerous parts vary
Disadvantages
Relies on operator to move to correct position
May obscure visibility during use
5. 2-hand control devices
Principles
Provides a level of protection where guards are not practicable
Controls must be operated simultaneously by both hands ensuring safety
Advantages
Ensures operator's hands remain outside danger zone during use
Disadvantages
Only protects the operator's hands
Does not protect other areas of the body
6. Hold-to-run devices
Principles
Operator has to 'hold' a button, stick or foot pedal
If not held, machine stops operating
Advantages
Ensures operator is out of danger area when the machine is operated
Machine switches off immediately if not in operation
Disadvantages
Can be easily defeated using an instrument of some kind
Machine will not stop immediately
7. Sensitive protective equipment devices (trip devices)
Principles
Use of sensors to detect a worker's presence in the danger zone
Sensors may be a light beam, pressure mate, cable or other mechanism
If sensor is tripped, machine is switched off
Advantages
May minimise the severity of injury
Disadvantages
May not prevent harm from occuring
Can be easily defeated by developing a method of access around or over the sensor
8. Jigs/push sticks (protective appliances)
Principles
When guarding is not practicable, protective appliances must be provided
Keeps operator's hands at a safe distance from moving parts
Advantages
Provides distance between operator and hazard
Inexpensive and easily replaced if damaged
Disadvantages
No physical restraint or barrier to prevent hands being placed in danger
Failure of protective appliance may cause additional hazard to operator
9. Emergency stop controls
Principles
Intended to provide a rapid response to potentially dangerous situations
Should be easy to reach and activate
Should not be used as functional stops during normal operation
Adavantages
Cuts off power immediately once activated
Equipment has to be reset after use (no accidental start up)
Disadvantages
Does not prevent access to dangerous parts of machinery
May be incorrectly positioned making access difficult
10. Information, instruction, training & supervision
Legal position
The provision & Use of Work Equipment Regulations 1998 require persons who use equipment & persons who supervise or manage the use of work equipment to have knowledge of:
Hazards associated with the equipment
Conditions in which and methods by which the equipment may be used
Foreseeable abnormal situations & the action to be taken
Written instructions for use of the equipment
Requirements for cleaning & maintenance
Requirements for reporting of defects
Advantages
Easy to reach a wide audience
Can be applied immediately & adapt for the user
Disadvantages
Relies on individual to follow instructions
Information & instruction may be misunderstood
Supervision does prevent contact with the hazard
In addition
PPE
Principle
Used as a last resort when all other controls have been considered
Advantages
Easy to see whether it's being worn by the operator
Provides protection against a variety of hazards
Disadvantages
No substitute for effective guarding
May not provide adequate protection against hazards
Maybe pose additional hazards (e.g. gloves becoming entangled)