Workshop, its Applications and Safety Considerations

Workshop safety means working in a way that prevents injury to people and damage to machines. The main rules are grouped below.

Personal safety

• Wear close-fitting overalls or apron with sleeves buttoned or rolled up; no loose clothes, ties, rings, watches or scarves near rotating parts.
• Tie long hair or cover it with a cap.
• Wear safety shoes, goggles or face shield (grinding, chipping, welding), gloves (welding, hot work) and ear protection where noise is high.
• Never wear gloves while working near a rotating drill or lathe spindle.

Machine and tool safety

• Learn the machine and its emergency stop before starting it; operate only with the instructor's permission.
• Fix guards over belts, gears, chucks and grinding wheels; never remove them.
• Clamp the job and tool firmly; remove the chuck key before starting the lathe.
• Stop the machine before measuring, cleaning, oiling or changing speed.
• Do not remove chips with bare hands; use a brush or hook. Do not use compressed air to clean clothes.
• Use sharp, undamaged tools with properly fitted handles. Keep mushroomed chisel heads ground.

Housekeeping and general rules

• Keep floor clean, dry and free from oil, chips and obstruction; keep passages clear.
• Store tools in their place; keep heavy items low and stable.
• No running, joking or distracting a person who is operating a machine.
• Know the position of the first-aid box, fire extinguishers and exits.

Electrical and emergency

• Check earthing of machines; do not touch switches with wet hands; report damaged cables.
• Report every accident, however small, and give first aid at once.
• Keep inflammable liquids in closed metal containers away from sparks.

Fire needs fuel, heat and oxygen (the fire triangle). Removing any one of them extinguishes it.

Classes of fire and suitable extinguishers

Water must not be used on oil fires (it spreads the burning oil) or on live electrical fires (shock hazard).

Carbon dioxide (CO2) extinguisher

It is a steel cylinder holding liquefied CO2 at high pressure (about 50 bar) with a valve, a discharge hose and a horn (a metal horn is avoided on electrical fires since it may conduct).

   [Valve + pin]
        |
   +----+----+
   |  CO2    |-----> hose --> horn
   | (liquid)|
   | dip tube|
   +---------+

• Working: the safety pin is pulled and the valve opened. Liquid CO2 rises in the dip tube and leaves through the horn, where it expands suddenly to gas and cools to about -78 °C as dry-ice snow.
• Action: CO2 is heavier than air, so it forms a blanket that displaces oxygen (smothering) and also cools the fuel.
• Use: Class B and electrical fires, as it leaves no residue and is non-conducting. It is poor for Class A deep-seated fires.
• Precaution: aim at the base of the fire; in a closed room CO2 can cause suffocation.