Pump Accessories
Back-Pressure Valves
Description
Back-Pressure Valves (BPV) apply positive discharge pressure to the chemical metering pump system to prevent siphoning and eliminate varying dosage rates caused by fluctuating downstream pressure. An internal spring holds the diaphragm against the valve seat. The spring tension, and pressure setting, can be adjusted by a nut on top of the valve.
Application
Generally, back-pressure valves are recommended and required for diaphragm pumps. There are a few reasons:
- Diaphragm pump output volume is dependent on discharge pressure. For a diaphragm pump running at a constant speed, an increase in pressure will result in a decrease in flow; and a decrease in pressure will result in an increase in flow. Setting a back-pressure valve at a pressure above typical system pressure will allow constant pressure on the pump, resulting in a constant, reliable flow.
- A system with discharge pressure below 30 psi may not provide enough back pressure to consistently seat the check valves located at the pump head. Installing a back-pressure valve at or above 30 psi will allow the ball checks to fully seat and ensure the pump provides consistent flow.
- Systems where the discharge point is lower in elevation than the pump can result in the siphoning of process solution through the pump. A back-pressure valve located close to the discharge point will prevent siphoning.
Installation
Back-pressure valves should be installed close to the injection point. Although in many cases it is simpler to install the valve on the pump skid.
Back-pressure valves should be installed in conjunction with a pressure gauge so the valve can be properly set to the correct pressure.
Adjust the pressure setting by rotating the nut or screw at the top of the unit.
Blue-White offers back-pressure valves as an option on pump skids. They can also be purchased separately.
Ordering Information
Materials available: PVC, CPVC, and PVDF bodies. EPDM, FKM, or Teflon diaphragms.
Pressure ranges: 10-150 psi
Connection types: ½” Socket, True-union, or Unibody.
| Part number | Description | Material | Size (in) |
| 90008-923 | Back-Pressure Valve, True Union, ½” Socket | PVC/FKM | 0.50 |
| 90008-939 | Back-Pressure Valve, True Union, ½” Socket | PVC/EP | 0.50 |
| 90008-925 | Back-Pressure Valve, True Union, ½” Socket | CPVC/FKM | 0.50 |
| 90008-926 | Back-Pressure Valve, True Union, ½” Socket | CPVC/EP | 0.50 |
| 90008-887 | Back-Pressure Valve, Unibody, ½” Socket | PVC/FKM | 0.50 |
| 90018-034 | Back-Pressure Valve, Unibody, ½” Socket | PVC/EP | 0.50 |
| 90018-003 | Back-Pressure Valve, Unibody, ½” Socket | CPVC/FKM | 0.50 |
| 90018-035 | Back-Pressure Valve, Unibody, ½” Socket | CPVC/EP | 0.50 |
