The WFI/PW loops are widely used in the pharmaceutical industry for producing and distributing this type of water to various parts of the plant .A typical WFI/PW distribution loop is an accumulation tank with two pumps that normally work in parallel and in alternation to maintain the loop pressure.The pumps are provided with a frequency converter controlled by a flow rate transmitter to keep the pressure stable regardless of the number of open of use .The distribution loop is complemented with auxiliary elements like overpressure valves ,check valves ,diaphragm valves,ultraviolet lamps and heat exchangers.

The Main difference between a PW and a WFI loop is that the purified water is held at room temperature while the WFI is kept at 80-90℃.In fact, it means that a loop heat exchanger must be used to cool and heat the PW(during the sanitation process)and to heat and maintain the temperature of the WFI.

Another important difference is that the WFI loops must be provided with cooled points of use to cool the water before use .