Hazards and Fire

Hazards and Fire Points : hazards and fire, safety against rotating machine hazards general measures should be adopted Safety against Rotating Machine Hazards General Measures Should Be Adopted Rotating machine is a machine which has one or several rotating parts. An electric motor has rotating part and is actually a rotating machine but it is not called a machine; it is called a motor. This motor drives many machines which have rotating parts and are called rotating machines.

As there are many types and sizes of rotating machines so there are many types of rotating machine hazards. For example there are hazards of exposed gear wheel, of unguarded circular saw, of unguarded belts and V-belts, of unguarded pneumatic conveyors, of unguarded feeding points, of unguarded rollers and of unguarded hairs etc,

Before enumerating rotating machine hazards and describing measures of preventing them it will be worth while to have at least a broad concept of the.
a) Operation of rotating machines, and
b) Size of such machines a) I-Operation of Rotating Machines Rotating machines are operated by electric motor through the following system:
a) Direct — drive, system
b) Indirect drive system a) Direct Driven System Direct driven system is the system in which rotating part of the attached machine is mounted on the rotating shaft of the electric motor an in a fan is in a drilling machine of small size. The most common hazard of machines driven through this system is that the rotating part of the attached machine is not mounted properly and tightly on the motor shaft, consequently it comes out of the grip and injures the operator. To avoid this hazard the rotating part of the attached machine must be mounted properly. b) Indirect Driven System In this system in which there is a belt in between the motor shaft and the attached machine. The belt runs over two pulleys, one pulley is fixed on the shaft of the motor and the other on the machine as in a flour grinding mill of small size or in a cane crushing important hazard of machines driven by this system is that running nip is created by the belt running over the pulleys. Running nip occurs when a material (may be the operator or a person in the vicinity) runs over the running belt, and consequently (i) dashes with the wall or any other machine and is injured or (ii) is trapped in between the belt and the pulley and is injured. (NB: More information about running nips will be given at a later stage.) To avoid this hazard the belt must be guarded. (a) Chain Driven System Is the system in which a wheel with sprockets (teeth on the rim of the wheel) is fixed on the shaft of the motor and another wheel with sprockets is fixed on the attached machine and a chain runs over these two wheels as in a bicycle. Unguarded chain is a hazard. Nip is created by the running chain over the toothed wheels. Sleeves or any other hanging cloth of the operator may be caught in between the chain and sprocket and may result in injury to the operator. To avoid this hazard the chain must be guarded (b) Gear Driven System Is the system in which a wheel with sprockets is fixed on the shaft of the motor and adjacent to it is another such wheel. This process is repealed required time. A motor car runs according to this system. Exposed gear wheel is a hazard. Loose sleeve or any part of loose clothing may be caught by the wheel which may drag the operator due to which he may fall down and injure himself. Exposed gear wheel may injure the fingers or hand of the operator or any other body in the vicinity if he is unmindful of the gear wheel. To avoid this hazard the gear must be closed within a gear box. II Size of Rotating Machines Some machines are only of the shall size while other are of small and large sized both. The small size machines are simple and are operated through any one of three system. The large size machines are complicated and employ more than one system for example a simple small size cane crushing machine which is found in a road-side cold drink stall operates according to belt drives system whereas sugar cane crushing machines in a sugar mill are complicated and employ the different systems in their different parts; actually the large size machines are a combination of several independent machines which are put together in a plant. Another example can be given of a cylinder printing machine which is found in medium size presses. Do’s and Do Not In Industrial Work • Wear adequate protective or tight clothes.
• Make sure that insulation of cables is in good condition.
• Put on insulated / rubber boots before touching any cable, cutout, switch board etc.
• Make sure that all electrical joints are sound.
• Respect warning notices pasted in the unit.
• Treat all cables LIVE.
• Put the switch off before replacing a blown fuse.
• Put the switch off if you see any person has come in contact with LIVE conductor.
• Make sure that the electric equipment is properly earthed before supplying current to it.
• Maintain good ventilation before charging cell in a room.
• Examine frequently the flexible cable for insulation defects.
• Make sure that flexible cables do not become the person being tripped up.
• Display at prominent places instructions for the treatment of electric shock.
• Tape joints and loose ends of conductors.
• Use only hand tools suited to work being done and SC) reduce the danger of short circuits.
• Ground the coils before touching then.
• Handle grinding wheels carefully.
• Keep away from belts and moving parts.
• Make sure that the work piece has been hold tightly in the vice.
• Make sure that the bit in of the correct size it has been fixed correctly in the (chak) and the (chak) has been fixed tightly with the key.
• Avoid doing things by UNPRESCRIBED METHOD; unprescribed methods are always UNSAFE METHODS and unsafe methods cause accidents.
• Avoid short cuts, adopt prescribed methods. DON’T • Wear loose clothes.
• Take risks.
• Touch cables with naked hand.
• Use bare figures or hands to find out whether the circuits is alive.
• Disconnect plug point by pulling the flexible wire.
• Energize a conductor unless you are sure that all is clear and no one is working on it.
• Touch over-head unless you are sure that it is dead and properly earthed.
• Clean rollers while in motion.
• Touch a person who is in contact with a live conductor.
• Allow any flame to come near any accumulator.
• Drag flexible cables over floors and rough surfaces and on damp ground.
• Sit on, stand on or pass through belts whether the belt is in motion or at rest.
• Allow tools dusters, wiping cloth or oil cones to catch in moving parts of a machine.
• Use metal bar to turn over the rotor of any energized machine.
• Use metal rule or tape or metal-reinforced fabric tape near live circuits.
• Use air hose with metallic coverings or fittings around live circuits or electric apparatus.
• Use a flashlight with metal case near live parts.
• Leave joints or loose ends of conductors untapped.
• Make any change in equipments or lines unless you have fully understood the effect of the change.
• Move carelessly in between the machines.
• Do any thing by UNPRESCRIBED METHOD, unprescribed methods are UNSAFE METHOD and unsafe Methods cause accidents.