The SRD Pressure Reducing Valves provide smooth, steady and precise pressure control from maximum to virtually zero flow without the need for low-flow bypass valves. The effective area of a single rolling diaphragm remains constant so the bonnet is much smaller and lighter than a flat diaphragm version. A measured quantity into the bonnet control chamber always gives the same smooth movement of the inner valve through the entire stroke. A smaller bonnet also makes the valve lighter and safer for maintenance, while the smaller control chamber enables it to respond faster to changing pressures. By eliminating the seat chatter at low flows, the SRD avoids injecting small pressure pulses into the piping, which, over time, may increase leakage, losses or pipe bursts.