24. (a) Briefly explain why multiple zones are needed for the Fire Hydrant/ Hose Reel (FH/HR) systems of tall buildings. ( 5 marks) (b) Briefly explain why a drencher system is required for refuge floors. Estimate the required water storage for a drencher system covering 30m2 open area of a refuge floor. (7 marks) (c) A horizontal pipe is between Pump A and a measuring point B, the pipe is (20+X)m long and an alarm valve of swinging type is at the middle of the pipe. The C value of this pipe is 100 and the nominal diameter is 150mm. Assuming the flow rate is 900L/min, estimate the required pump pressure if the pressure at point B is required to be 5 bar. (In Q,X is the 2 nd digit of your student ID number. e.g. X=2 if your student ID is 12345678G.) (d) For a FH/HR system, the topmost fire hydrant is 60m above the intermediate booster pump (IBP), and the pipe length between IBP and this fire hydrant is 80m. The Fire Service Inlet in this FH/HR system is 3m above the IBP. Ignoring the friction induced pressure loss, determine the required booster pressure at IBP. (6. marks) Hazen-Williams Formula