Parker Relief Valves are designed such that when upstream pressure exceeds the closing force exerted by the spring,the lower stem opens,permitting flow through the valve.
Relief Valves
> RL4 Series
• Handle for field maintenance
• Externally adjustable pressure settings
while valve is in operation
• Color coded springs and labels indicate
spring cracking range
• Manual override option with positive stem
retraction is available for the full working
pressure range
• Seven different springs
​
> RH4 Series
• Eight springs
• Manual override option with positive stem
retraction is available for pressures up to
1,500 psi (103 bar)
• Preset from factory and comes with
standard springs
> HPRV – PED High Pressure Proportional Relief Valve
• Captured moulded seat design is blow-out
and chip resistant
• Color coded springs and labels indicate
spring cracking range
• Unique Tru-Loc facility prevents accidental
adjustment
• Low friction stem seal design prevents
friction which increases accuracy of
cracking pressure and reseat pressure
• Balanced poppet design ensures
consistent cracking pressure regardless of
system back pressure
• Multiple end connections available
> HPRV – PED Low Pressure Proportional Relief Valve
• Pressure settings are externally adjustable.
Six different spring ranges provide greater
system sensitivity and enhanced
performance
• Back pressure has minimum effect on
cracking pressure
• Color coded springs and labels indicate
spring cracking range
• Orifice sizes: 5.2mm (0.203")
• Lock wire feature secures a given pressure
setting
• Multiple end connections available
