iosh msqp machinery
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IOSH MANAGING SAFELY Preventing Accidents & Incidents in the Oil & Gas Sector
in partnership with
TOBY CLARK BSc FIOSH AIEMA MCot Cert Ed
IOSH MANAGING SAFELY
MODULE 4
Machinery Safety
Mechanical Hazards
BS EN 292• Crushing – caused when part of the body is caught between
either two moving parts of machinery or a moving part and a stationary object
• Shearing – When two or more machine parts move towards/past one another a “trap” is created. Can result in a crush injury or amputation e.g. power presses, guillotines, scissor lifts
• Cutting/severing – Saw blades, knives and even rough edges, especially when moving at high speed. Can result in serious cuts or amputation e.g. saws, slicing machines, abrasive cutting discs
Examples of in-running nips
Guarding arrangements for drilling machines
Working at a guillotine – risk of crushing & amputation of fingers
Clear plastic fixed guarding at a milling machine
Protection against Machinery Hazards
Photoelectrical Safety Systems• Operate on the principal of the detection of
an obstruction in the path taken by a beam or beams of light, a curtain or light or any combination of these necessary to provide the required safeguard
• The light may be visible or invisible, continuous or modulated
Proximity sensor
Light curtains at a weaving machine
Rotating light curtain
Rotating light curtain
Testing the integrity of a light curtain
Power press guarding
Mechanical Hazards
• Entanglement – caused by revolving parts of machine. Risk increased by loose clothing, jewellery, long hair etc. E.g. couplings, drill chucks/bits, flywheels, spindles and shafts (especially those with keys/bolts)
• Drawing in/trapping – caused when a belt runs round a roller e.g. conveyors
• Impact – caused by objects which strike the body but do not penetrate
Guarding on a chainsaw source Health & Safety Executive
Circular saw
Width setterShrouded on-off switches
Blade guard
Abrasive wheel
Lathe
Mechanical Hazards
• Stabbing/puncture/ejection – The body may be penetrated by flying objects such as broken pieces of machinery or sharp pieces of machinery (drill bits) or ejection of material (swarf/sparks)
• Friction/abrasion – Friction burns or abrasion injuries can be caused by coming into contact with smooth surfaces moving at high speed (grinding wheel)
• High pressure fluid injection – Injection of fluids through the skin. Air or hydraulic oil entering the blood stream through the skin may be fatal. Immediate medical assistance is essential
Protection against Mechanical Hazards
Fixed distance guard
• Does not completely cover the danger point but puts it out of normal reach
• A distance guard which completely surrounds machinery is commonly called a perimeter-fence type guard (1.8m high)
Fixed enclosing guardFine mesh prevents fingers reaching moving parts
Moving parts visible
Ventilation prevents overheating
Doesn’t stop noise
Should contain broken belt and fragments
Tools needed to remove guard
Belt tensioner and drive motor•fixed perimeter fence•access via interlocked door•residual risk of falling in from above
Protection against Mechanical Hazards
Anthropometric considerations
• Guards should be designed and constructed with the object of preventing any part of the body from reaching a danger point or area. They should take account of the physical characteristics of the people involved, and their abilities to reach through openings, over or around barriers or guards
Protection against Mechanical Hazards
Key Dimensions
Protective Structure
Danger zone
Reference planea b
c
.a Height of danger zone
.b Height of protective structure
.c Horizontal distance to danger
Protection against Mechanical Hazards
Interlocked guards• Similar to a fixed guard but has a movable
(usually hinged) part connected to the machine controls so that if the movable part is open/lifted, the dangerous moving part at the work point cannot operate.
• Until the guard is closed the interlock prevents the machine from operating
• Or the guard remains closed until the risk of injury has passed
Perimeter fence 2.4m high
Door with interlocks
Protection against Mechanical Hazards
The four media for interlocking guards are electrical, mechanical, hydraulic and pneumatic
Guard locking systems • motion or position sensing devices – photoelectric
beam• Timing devices – delay relay, mechanical, electric
or electronic clocks• Guard locking devices – captive key/trapped key
Dual Electrical Interlock with cross-monitoring
Protection against Machinery Hazards
Automatic guards• Moved into position automatically by the machine
thereby removing any part of a person from the danger area sometimes known as a ‘sweep away’ guard.
• Operates by physically removing from the danger area any part of a person
• It can only be used where there is adequate time for such removal to take place without introducing any further danger
Protection against Machinery Hazards
Trip devices• A trip device is a device which causes working
machinery to stop or assume an otherwise safe condition while a person remains within the danger area
• Designed to ensure that an approach to a dangerous part beyond a safe limit causes the device to operate and the dangerous part to stop
• May be reset automatically or manually after operation
Protection against Machinery Hazards
Pressure sensitive mat system• Contains sensors which operate when a
person or object applies pressure to the mat. • May be exposed to potential damage which
can result in failure.• Dimensions should take account of speed of
approach, length of stride and overall response time
Protection against Machinery Hazards
Adjustable guard
• A fixed guard which incorporates an adjustable element (which remains fixed for the duration of a particular operation) e.g. on a pillar drill or circular saw
• Opening may be adjusted to accommodate material
Adjustable guard
Riving knifeFixed enclosing guard
Guarding a circular saw. Power takeoff (PTO) should also be guarded
PTO
Protection against Machinery Hazards
Self-adjusting guard• Prevents accidental access by the operator but
allows entry of the material in such a way that the material actually forms part of the guarding arrangement e.g. hand held circular saw
• Opened by passage of the workpiece• Returns to safe position on completion of the
operation
Protection against Machinery Hazards
Two hand controls
• A device which requires two hands to operate and therefore protects the hands of the operator
• Protects only the operator
Protection against Machinery Hazards
Emergency stop devices• The function of an emergency stop device is
to provide a means to bring a machine to a rapid halt.
• It should be easy to operate and clearly discernible from other controls
• Should be readily available to the operator and/or others
Light curtains
Emergency stops
Provision and Use of Work Equipment Regulations
Regulation 11 – Dangerous parts of machinery (hierarchy of control)
• Fixed guards
• Other guards or protection devices
• Provision of jigs, holders, push-sticks or similar protection appliances
Push stick
Non-mechanical hazards
• Electricity – power generated at a variety of voltages, alternating/direct current, stored energy, static electricity, batteries (chemical)
• High/low temperature – Many processes rely on the input of high or low temperature as part of the process or process may evolve high or low temperatures
Non-mechanical hazards
• Radiation – may be ionising or non-ionising
• Hazardous substances – may be part of the process, evolved or introduced along with materials by mistake e.g. vapours released or substances carried on materials from a prior process
Non-mechanical hazards
• Noise – noise sources from equipment may be from such things as bearings that are loose or worn, materials falling into or out of equipment or from air exhausted from equipment
• Vibration – vibration may be designed as part of the process or a result of moving parts of the equipment such as conveyor systems and rotating parts