Parker R Series Relief Valves are unique since they offer both a low pressure valve line (RL4) and a higher pressure valve line (RH4). They are both designed such that when the upstream pressure exceeds the closing force exerted by the spring, the lower stem opens, permitting flow through the valve. Flow through the valve increases proportionately to the increase in upstream pressure. These relief valves work from 1-25 psig crack pressure systems up to 5,000-6,000 psig crack pressure systems. The highly visible color coded labels on the valves indicate the associated crack pressure spring included in the valve.

To assist the installer, these valves are offered with a wide range seal materials. From Ethylene Propylene Rubber at -70F to Fluorocarbon Rubber at 400F, these relief valves meet numerous applications.

Markets:
• Chemical
• Petrochemical
• Oil and Gas
• Research

Features/Benefits:
• Pressure settings are externally adjustable while the valve is in operation. Multiple spring ranges provide greater system sensitivity and enhanced performance.
• Captured molded seat design is blow-out and chip resistant.
• Manual Override option with positive stem retraction is available for pressures up to 1500 psig (103 bar).
• This option permits the user to relieve upstream pressure while maintaining the predetermined cracking pressure.
• Color coded springs and labels indicate spring cracking range.
• Lock wire feature secures a given pressure setting
• Back pressure has minimum effect on cracking pressure.

Applications:
• Process Control Lines
• Research Equipment
• Monitoring Lines