QUESTION 1
a. You have been requested by the owner of a metal workshop to develop a safety program to help reduce the risks of electrical hazards. Outline some of the safety policies you would include in the program
b. In terms of personnel education and formation, suggest some important steps that the management can take to reduce the risk of mechanical hazards during operation of machines in a metal workshop
QUESTION 2
A process worker received an electric shock when she attempted to turn off a conveyer control. The toggle switch controlled the power to a variable speed drive. An examination found that dust had accumulated on the toggle switch. Moisture on the woman's hand caused tracking, resulting in the electric shock. The only protection for the single-phase supply was a circuit breaker. The factory machines were subsequently fitted with RCD socket outlets
a. Explain how an electric shock may occur
b. Explain the effect of the moisture on the worker's hand that has resulted in the electric shock. c. Describe the different factors that may affect the severity of an electric shock on the body
d. Although the installation was equipped with a circuit breaker, a residual current device (RCD) was recommended. By explaining the working principles of a circuit breaker and an RCD, differentiate between the two.
QUESTION 3
A worker had his arm severed above the elbow when he was adjusting the inner front lay of a die-cut machine. The machine essentially prints and cuts cardboard boxes. The worker's spanner felt down and his arm was caught in the rotating flywheel when he was about to retract his arm. Examination concluded that the worker did not adhere to safety precautions and that inadequate measures were taken to prevent contact with moving parts.
a. Describe the safety precautions that the worker should have taken while carrying out the adjustments
b. One method of preventing contact with moving parts is guarding. Describe the different types of guards and state, justifying your answer, the type of guard you would have recommended for the rotating flywheel
c. Describe how environment conditions can also help increase the risk of accidents involving machines.
QUESTION 4
An air compressor takes the air in a room and forces it into a container (an air receiver) under pressure. Compressed air is used to power a variety of tools and machinery. For example compressed air is used to power pneumatic wrenches and lifts in automobile service stations.
a. In relation to an air receiver, what do you understand by the following
(i) Design Pressure
(ii) Maximum Operating Pressure
(iii) Operating Pressure
b. What is the maximum pressure at which a safety valve can be set to lift?
c. List and describe the importance of four safety components of an air compressor with air receiver
d. A motorist laid an LPG cylinder on its side in the passenger foot well in order to stop it falling over while the car was in motion. The barbecue regulator and hose were still attached. Having stopped to search for a mislaid item, he lit a cigarette. A fireball blew out the front windows of the car, shifting it several metres and causing burns to his face, arms and one leg.
(i) Provide a possible explanation for the accident
(ii) Suggest few safe practices to prevent such accidents