Class 4 (4th Engineer) SSEP 📅 Mar 2023

Exam Question

(a) Sketch and describe a 50Lts mechanical foam fire extinguisher, giving details with respect to: (10)

(i) Type of gas used as explants

(ii) Throw reach

(iii) Working and test pressure

(b) Explain the procedure for re-charging the same after use (10)

Reference Answer

### (a) 50Ltr Mechanical Foam Fire Extinguisher
A 50-litre mechanical foam fire extinguisher is a mobile unit designed for tackling large Class B fires (flammable liquids) and can also be used for Class A fires (combustible solids). Its operation is based on smothering and cooling the fire by creating a foam blanket that separates the fuel from the oxygen supply and provides a cooling effect from its water content.
#### Construction and Operation
* **Main Cylinder**: A robust steel cylinder with a capacity of 50 litres, mounted on a wheeled trolley for mobility.

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