Foot Valve:

Using a Foot Valve? Enter “1” into text box if a foot valve will be used. Calculation is based on hinged disk type valve with strainer, If a poppet type valve is used the friction loss is much higher, enter a higher number for small sizes and a smaller number for larger sizes, ie: enter “7” if 15mm, “6” if 25mm, “5” if 50mm and “4” if 150mm etc.  Note: Using larger valves will normally reduce friction loss but there is a critical velocity required to allow valve to open correctly, under which excessive friction losses or hammering may occur.