 Fire Service Manuals provide tables of maximum volumetric flow rates for a given pump pressure, hose diameter and total hose length.The use of these tables, is to facilitate the selection of suitable hoses, taking into account the frictional losses caused by transporting water through the strainer, hoses, pump and fire fighting nozzles, to draft water from source to the fireground.When being used in a drafting operation from a pool, portable water tank, or other uncovered water source, the length of suction hose farthest from the pump is usually attached to a strainer, to keep foreign objects in the water from being pulled into and damaging the pump.