- Priming of pumps in all cases should preferably be by positive suction. This can be:
achieved by having the pump house at lower level than the water tank, so as to have a permanently flooded suction. However, where this is not practicable, priming with the help of a priming tank with a foot valve and strainer arrangement may be used. The capacity of priming tank should be 8 times the total volume of the suction pipe, from pump up to the foot valve.
- For wet-riser-cum-down-comer system, two pumps of different capacityone for the wet-riser (for static tank) and the other for down-comer system (for terrace tank) should be installed. The pumps should be fed from normal source of power supply and also by an alternative source in case of failure of normal source of supply.
- For a wet-riser system two automatic pumps should be installed to feed the wet-rising main, one of which should act as stand-by, each pump should have different source of power and so arranged that when acting as duty pump, it will operate automatically when one or more hydrant/hose reel is opened thus causing a drop in pressure. The stand-by pump should be arranged to operate automatically in case of failure of the duty pump. There should be an interlocking arrangement between two main pumps so that only one should come into operation at a time.
- An arrangement for supply of alternative source of power automatically should be provided to drive pumps, etc, in case of failure of normal power supply. The alternative source should be one of the following:
- Supply from a diesel generating set of adequate capacity to meet full requirement of fire pump(s) including initial current for direct on line/star-delta starting device over and above the other requirements like automatic fire detection and alarm system, fire lift, staircase and corridor lighting circuits, fire pumps, pressurization system and mechanical exhaust system, etc, with automatic changeover. Fire pump may be connected to diesel engine having same power as that of electric fire pump with automatic changeover in case of power supply failure with interlocking arrangement.
- A power supply from separate sub-station for operating emergency services mentioned.