Equipment and Appliances
What the exam tests
Equipment and Appliances covers pumps, primers, hose, couplings, branches, ladders, breathing apparatus and extinguishers: identification, safe use, testing and common faults.
Core rules
- Centrifugal pump: the impeller throws water outward; it must be primed because it cannot self-evacuate air. Priming methods include exhaust ejector, vacuum pump and water-ring.
- Hose: suction hose is rigid and kept under negative pressure; delivery hose carries pressure. Friction loss rises with flow, length and roughness, and falls with larger diameter.
- Nozzle pressure is the pressure at the branch; pump pressure must add friction loss and elevation. In bar: PP = NP + FL + elevation (positive if uphill).
- Ladders: use about 75° for general access; heel the ladder, secure the head and maintain three points of contact.
- Extinguishers: water (A), foam (B), CO2 (B and electrical), dry powder (ABC; special powders for D), wet chemical (K).
Worked example
A branch requires 5 bar nozzle pressure. Hose friction loss is 2 bar and the branch is 10 m above the pump (about 1 bar). What pump pressure is needed? PP = 5 + 2 + 1 = 8 bar. Reasoning: the pump must overcome nozzle, friction and height. If the branch is below the pump, subtract the elevation term.
Traps
Confusing suction and delivery hose; forgetting to prime; using a kinked hose at full pressure; mixing couplings under pressure; assuming CO2 is suitable for a deep-seated Class A fire.