Backpressure Regulator (BPR) is a self-contained, medium driven, modulating automatic pressure control device designed to maintain sufficient pressure in the upstream piping to minimize/prevent cavitation and/or flashing in a piping system with varying flow rates. The fluid must be maintained above vapor pressure from zero flow to maximum flow allowed by the BPR at velocity not to exceed 20 feet/second.
The BPR is custom designed to meet each specific application to protect the control device upstream that is varying the flow and pressure to the BPR.
The spring is selected to maintain a predetermined crack open pressure of x psi pressure (usually 30 psi approx. above the vapor pressure of the specific liquid). The opening pressure is increased with an increase in liquid flow through the BPR to x psi times 2.5 at full open.
The plug compresses the spring as pressure and flow increases and allows a modulating opening of the flow ports that are drilled in the guide bushing. These flow ports are located immediately behind the plug seat on the guide bushing.
The flow port size is determined by the upstream pressure required and BPR delta P required. This allows for protection at low flows when line losses are minimal and at high flows when line losses are much greater.