Flo-Trol® automatic flow control valves are designed to give constant flow over a wide pressure range. The internal controlling mechanism has no moving part, consisting only of a flexible orifice that varies with applied pressure maintaining a constant flow rate. Flow rates are maintained to within ±15% between 15 and 125 PSI (1 to 8.6 bar). The flow rate varies due to manufacturing tolerances and water temperatures. Valve bodies are stainless steel (not chrome or nickel-plated brass) with a Buna-N orifice (NSF/ANSI 61 certified).