Back Pressure Valve for Positive Displacement Pump
Application
In most of the positive displacement metering pumps, for smooth and accurate metering, pumps need a discharge pressure at least 40 Psi greater than system suction pressure.
Consider typical example, when pump is being fed from an elevated suction tank with little or no discharge pressure. Without getting higher discharge pressure built up, erratic metering will result due to siphoning of the process liquid from the tank through pump and into the system. When discharge is into the vacuum process, problem is still worse.
With a view to over-come above, a back pressure valve (BPV-1) is installed in the discharge line of a pump to create a higher pressure between BPV-1 and pump than the system suction pressure. Here it is important to emphasize that back pressure valve should not be confused with a pressure relief valve. Pressure relief valves operates only to relieve an over pressure, whereas Back Pressure valves operates constantly and proportionally while the pup is running.
Similarly, in case of any failure / malfunctioning of a back pressure valve installed on main discharge line, choking of filter or any other reason if the pressure in main discharge line increases abnormally, this will cause back pressure on pump as well as a whole piping system will be charges by high pressure. To avoid this, another back pressure valve BPV-2 is used on bypass line. This will open only when safety set pressure is reached and will bypass the excess flow to suction.
Features & Advantages:
- Enables easy building up of higher discharge pressure, resulting smooth, accurate and stable metering.
- Optimum efficiency of the pump is achieved.
- Back Pressure Valve is pressure multiplier, whoch allow the valve to observe even a small pressure changes and react with much greater force for a response.