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You can also review the documentation for technical details and purchasing information.
- M-Series (PRM) Datasheet
- G-Series (PRG) Datasheet
- High Flow (PRHF) Datasheet
- Unibody (PRU) Datasheet
- Medium Pressure (PRMP) Datasheet (imperial)
- High Pressure (PRHP) Datasheet (imperial)
- Relief Valve with Pressure Switch (PRS) Datasheet (imperial)
- M-Series Installation Manual
- G-Series Installation Manual (DN 15 – DN 50)
- G-Series Installation Manual (DN 80 & DN 100)
- High Flow Installation Manual
- High Pressure Installation Manual
GRIFFCO Pressure Relief Valves
- Product Details
- Specifications
- Applications & Features
GRIFFCO Pressure Relief Valves
Protects the Pump and Pipework from Over-Pressure
A dosing pump keeps pushing even when its discharge line is blocked: a closed valve or a clogged injection quill can build pressure until a tube, fitting or pump head bursts. A pressure relief valve is the safety valve that stops this.
In normal running it stays shut. If the pressure rises past its set point, a spring-loaded diaphragm lifts and sends the excess chemical back to the tank or the pump suction, and the valve closes again once the blockage is cleared.
Fit it close to the pump, with no valve between the pump and the relief valve, and set it about 1 bar above the normal working pressure. Valves leave the factory set at 3.5 bar.
Which Series?
- M-Series (PRM) – small dosing pumps, DN 8 – DN 15
- G-Series (PRG) – the main range, DN 15 – DN 100
- High Flow (PRHF) – larger flows and thick chemicals
- Unibody (PRU) – one-piece PVC or CPVC body with union ends
- Medium Pressure (PRMP) – all-metal, for 7 – 55 bar systems
- High Pressure (PRHP) – piston type, for very high-pressure pumps
- With Pressure Switch (PRS) – sends an alarm to the control panel whenever the valve relieves
Bodies come in PVC, CPVC, PP, PVDF, PTFE, Halar and metals (316 SS, Alloy 20, Hastelloy C), with BSP threads, metric socket, union and flange ends available.
Standard Series
| Item | M-Series (PRM) | G-Series (PRG) | High Flow (PRHF) | Unibody (PRU) |
|---|---|---|---|---|
| Sizes | DN 8 – DN 15 (¼" – ½") | DN 15 – DN 100 (½" – 4") | DN 15 – DN 50 (½" – 2") | DN 15 – DN 25 (½" – 1") |
| Ports | 3-port standard; 2-port and 90° optional | 3-port up to DN 25; 2-port all sizes | 2-port | 2-port |
| Connections | Threaded, socket, union, flange | Threaded, socket, union, flange (DN 80 & 100 flanged only) | Threaded, socket, union, flange | Union socket ends |
| Body Materials | PVC, CPVC, PP, PTFE, PVDF, 316 SS, Alloy 20, Hastelloy C | PVC, CPVC, PP, PTFE, PVDF, Halar, 316 SS, Alloy 20, Hastelloy C | PVC, CPVC, PP, PTFE, PVDF, Halar, 316 SS, Alloy 20, Hastelloy C | PVC, CPVC |
| Diaphragm | PTFE/EPDM standard; Viton, Hypalon, PTFE/Viton and others optional | |||
| Set Pressure (standard spring) | 1 – 10 bar, factory set at 3.5 bar | |||
| Optional Springs | 0.7 – 3.5 bar; 1 – 17 bar; 3.5 – 25 bar (metal valves) | 0.7 – 3.5 bar; 1 – 17 bar; 3.5 – 25 bar (metal, up to DN 25) | 0 – 3.5 bar; 1 – 17 bar | 0.7 – 3.5 bar |
| Maximum Pressure | 25 bar plastic; 138 bar metal | 25 bar plastic; about 138 bar metal | 25 bar plastic; 135 bar metal | 15.5 bar |
| Maximum Temperature | PVC 60 °C; CPVC, PP 90 °C; PTFE, PVDF, metal 150 °C | PVC 60 °C; CPVC, PP 90 °C; PTFE, PVDF, metal 150 °C | PVC 60 °C; CPVC, PP 90 °C; PTFE, PVDF, metal 150 °C | PVC 60 °C; CPVC 90 °C |
High Pressure and Alarm Series
| Item | Medium Pressure (PRMP) | High Pressure (PRHP) | With Pressure Switch (PRS) |
|---|---|---|---|
| Sizes | DN 8 – DN 25 (¼" – 1") | DN 8 – DN 25 (¼" – 1") | DN 8 – DN 25 (¼" – 1") |
| Type | Diaphragm, 2- or 3-port | Piston, 2-port 90° | Diaphragm relief valve with pressure switch |
| Connections | Threaded (NPT, BSPT), socket, flange (from ½") | Threaded (NPT), socket, flange | Threaded (NPT, BSPT), socket, union |
| Body Materials | 316 SS, Alloy 20, Hastelloy C, titanium | 316 SS, Alloy 20, Hastelloy C | PVC, CPVC, PP, PVDF |
| Set Pressure | 7 – 55 bar (100 – 800 psi) | PRHP: 24 – 172 bar (350 – 2,500 psi); PRHP4: 69 – 276 bar (1,000 – 4,000 psi) | 0.7 – 10 bar standard; 0 – 3.5 bar optional |
| Alarm Switch | – | – | Normally open (closed optional), 1 – 4 bar or 3 – 10 bar switch range |
| Maximum Pressure | About 138 bar (2,000 psi) | Top of the set range | About 15.5 bar (225 psi) |
| Maximum Temperature | About 149 °C (300 °F) | About 149 °C (300 °F) | PVC 60 °C; CPVC, PP 90 °C; PVDF 149 °C |
Applications
- Discharge line of diaphragm and piston dosing pumps
- Chemical dosing skids for water and wastewater treatment, process water and cooling towers
- Protection against closed valves, blocked injection quills and plugged lines
- High-pressure injection into mains, boilers and process lines (Medium and High Pressure series)
- Unattended sites that need an alarm when the valve opens (Pressure Switch series)
Key Features
- Opens at the set pressure and closes again automatically
- Relief flow returns to the tank or pump suction, so no chemical is lost
- Adjustable set pressure, factory set at 3.5 bar
- 3-port design up to DN 25 lets the dosing flow pass straight through; 2-port and 90° versions available
- Set pressures from 0.7 bar to 25 bar on the standard series, to 55 bar on Medium Pressure and higher on High Pressure
- PTFE-faced diaphragm as standard; Viton, Hypalon and other options to suit the chemical
- Wide choice of body materials, plastic and metal
- Diaphragm can be serviced without removing the valve from the line
- Made in the USA; NSF/ANSI 61 certified in PVC
Used with a Back Pressure Valve
A back pressure valve keeps dosing steady; the relief valve is the safety net behind it. Most dosing lines need both.
