RL4 Series Relief Valve
Specifications
Working pressure:
Up to 400 psig (28 bar) CWP
Up to 600 psig (41 bar) during relief with no internal seal
damage.
Cracking pressure:
Seven springs with the following ranges:
10-25 psig 25-50 psig 50-100 psig
(0.7-1.7 bar) (1.7-3.4 bar) (3.4-6.9 bar)
100-150 psig 150-225 psig 225-400 psig
(6.9-10.3 bar) (10.3-15.5 bar) (15.5-27.6 bar)
10-225 psig
(0.7-15.5 bar)
Temperature Rating:
Nitrile Rubber .......................................... -30°F to 225°F
.......................................(-34°C to 107°C)
Highly Fluorinated Fluorocarbon Rubber ...... -20°F to 200°F
.........................................(-29°C to 93°C)
Ethylene Propylene Rubber ...................... -70°F to 275°F
.......................................(-57°C to 135°C)
Fluorocarbon Rubber ................................ -10°F to 400°F
.......................................(-23°C to 204°C)
Neoprene Rubber ..................................... -45°F to 250°F
.......................................(-43°C to 121°C)
Introduction
Parker RL4 Relief Valves are 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.
Features
? Pressure settings are externally adjustable while
the valve is in operation. Seven different spring
ranges provide greater system sensitivity and
enhanced performance.
? Manual override option with positive stem retraction
is available for the full working pressures
range. This option permits the user to relieve
upstream pressure while maintaining the
predetermined cracking pressure.
? Color coded springs and labels indicate spring
cracking range.
? Back pressure has minimum effect on cracking
pressure.
? Lock wire feature secures a given pressure setting.

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