Parker RH4/RL4 Relief Valves – Up to 414 bar and 204°C with Adjustable Set Pressure (Inch)

Parker RH4/RL4 Relief Valves – Precision Overpressure Protection for Demanding Systems

Parker's RH4 and RL4 Series relief valves are engineered to protect instrumentation and process systems from overpressure in critical applications such as oil & gas, chemical processing, hydraulics, and power generation. These valves open automatically when system pressure exceeds the set point and reseal once pressure normalizes.

Key features:

• RH4 Series: Working pressures up to 414 bar (6000 psig), can relieve up to 552 bar (8000 psig) without internal damage
• RL4 Series: Optimized for lower pressure ranges from 10 to 400 psig with high sensitivity and repeatability
• Externally adjustable set pressure – easy in-field calibration
• Eight spring ranges for RH4 from 50 to 6000 psig
• Manual override option available for controlled venting without altering set pressure
• 100% factory tested for performance and safety

Seal material options:

• Nitrile (NBR)
• Fluorocarbon (FKM)
• EPR
• Neoprene
• Highly fluorinated fluorocarbon (FFKM)

Constructed from 316 stainless steel with excellent corrosion resistance. Parker also offers repair kits including springs, seats, and seals—extending service life and reducing downtime. The RH4 and RL4 Series are ideal for applications requiring precision, safety, and serviceability in compact, high-performance designs.