The RH4 and RL4 are instrumentation relief valves that open to release pressure when it reaches the spring set point. The RH4 is for high pressure, the RL4 for low pressure, and both have an SS316 body.
| Working Pressure | Up to 414 bar (6,000 psig) CWP (RH4) / up to 28 bar (400 psig) CWP (RL4) |
| Cracking Pressure | 3.4 to 413.7 bar, 8 springs (RH4) / 0.7 to 27.6 bar, 7 springs (RL4) |
| Temperature Rating | -57 to 204 °C (by seal material) |
| Seal Material | FKM / NBR / EPDM / neoprene / highly fluorinated FKM |
| Body Material | SS316 |
| End Connection | NPT (male, female) / tube compression (CPI, A-LOK) / BSP (male, female) |