Purified water(PW) & Water for injection(WFI)distribution loops:-
The water distribution loop must be made from sanitary materials of the same characteristics as those of the storage and distribution skid. The main characteristic is that they must be 100% drainable so they will be designed with gradients towards the points of use so that in the event of a shutdown of the installation no water will be retained in the loop. As for fluid mechanics, the water must circulate in the pipe in turbulent flow (speeds over 1.2 m/s and Reynolds number over 10,000 are advisable) in order to minimize risks of contamination which would occur if it were to circulate in laminar flow, a positive pressure must also be guaranteed in the return to the tank (1 bar). For this, various instruments will be used such as a variable speed drive for the pump, pressure probe and flow meter.
The loops must be correctly insulated in order to minimize heat loss, thus achieving considerable energy saving, and in clean rooms this must be of stainless steel .
The fixing of the installation must be made using sanitary pipe hangers covered with polymer material (according to the temperature) to minimize the risk of external corrosion of the pipe.
The main elements of the distribution loop are: