Description
Please enter the PSI setting you want your Final Safety Relief Valve set to. Normally, we set these to 10% above your pressure shut-off switch PSI setting if you have one or 10% above the pressure you are filling to. Valve includes a wire safety seal to prevent tampering with pressure setting.
Example:
shut-off switch PSI set to 3000 Final Safety Relief Valve would be set to 3300
fill to pressure is 4500 Final Safety Relief Valve would be set to 4950
What the Model 504 Relief Valve Does
The Aqua Environment Model 504 is a small, economical, high-pressure adjustable relief valve used to protect breathing air and high-pressure systems from overpressure. When system pressure rises above the valve’s set point, it vents to atmosphere through its side port, then reseats once pressure returns to a safe level. It offers precise set-pressure control across a wide range and stays bubble-tight to within a few psi of the set pressure, reseating reliably even after repeated venting.
Safety-wire holes are built into the valve so the set pressure can be locked in place once adjusted — useful where a calibrated relief setting must not be tampered with. The Model 504 is a common protection device on high-pressure compressors, fill stations, and air panels.
Key Specifications
- Type: Adjustable high-pressure relief / safety valve
- Maximum rated pressure: 6000 psi
- Set pressure adjustment range: 900–6000 psi
- Inlet port: 1/4″ NPT
- Outlet: Side vent to atmosphere (not captured)
- Flow capacity: 50 SCFM at 1500 psi; 100 SCFM at 3000 psi
- Leakage: Bubble tight
- Weight: 2.1 oz (60 g)
- Overall length: 2.5″
- Hex diameter: 0.87″
- Internal materials: Brass and stainless steel
- Seals: Viton
- Special feature: Safety-wire holes for locking the set pressure
Common Applications
The Model 504 is used for discharge and interstage relief on small high-pressure compressors, as a relief on charging lines, regulators, and manifolds, and for hydraulic system and accumulator relief — along with many other high-pressure safety-relief uses across SCBA, SCUBA, fire, paintball, and industrial systems.
Important Notes
- Set pressure above 5000 psi: Although the 504 is rated to 6000 psi, the manufacturer, Aqua Environment, recommends the Model 1607 relief valve for set pressures above 5000 psi.
- Oxygen service: This valve is not shipped oxygen-clean and should not be used for oxygen service.
- Safety wire: Safety-wire holes are provided on the valve, but safety wire is not included.
Frequently Asked Questions
What does a relief valve do?
It’s a safety device that automatically vents excess pressure if your system climbs above a set limit, protecting your compressor, lines, and equipment from overpressure damage. It reseats once pressure drops back to a safe level.
What pressure can the Model 504 be set to?
It’s adjustable across a 900–6000 psi range, with a 6000 psi maximum rating. For set points above 5000 psi, the manufacturer recommends the Model 1607 instead.
Can I lock the set pressure?
Yes. The valve has safety-wire holes so the adjustment can be wired and locked once set, though the safety wire itself isn’t included.
Can it be used for oxygen?
No. The 504 is not oxygen-clean and should not be used in oxygen service.
