Exam Question

### (a) Brief Description of an Explosimeter
An explosimeter, also known as a combustible gas indicator, is a portable instrument designed to measure the concentration of flammable hydrocarbon vapours in the atmosphere of an enclosed space, such as a cargo tank or a pump room. Its primary function is to provide a quantitative assessment of the explosion risk.
- **Purpose**: To detect and measure flammable gas concentrations below the Lower Explosive Limit (LEL), ensuring the atmosphere is safe for personnel entry or for carrying out hot work.
- **Principle**: It operates on the principle of catalytic combustion within a balanced electrical circuit known as a Wheatstone bridge.