Built to Perform. Certified to Protect.
Every Cyrus Shank relief valve is individually tested, lock-wired, and shipped ready to install. Our 110+ year manufacturing legacy means every valve that leaves Cincinnati is held to the same uncompromising standard.
ASME Certified
Manufactured in accordance with ASME Boiler and Pressure Vessel Code Section VIII Division I, stamped with the ASME Certification Mark with UV Designator.
Triple-Tested
Every valve undergoes 3 separate test sequences for set pressures and seals before leaving our Ohio facility. Each valve is then lock-wired for security.
Custom Set Pressure
Special settings can be made at no extra charge. Set pressure range 50–400 PSI in 25 PSI increments, with special settings typically completed within 1–2 extra days.
National Board Certified
Capacities are certified by the National Board of Boiler and Pressure Vessel Inspectors and stamped with the NB Certification Mark.
Lock-Wired Security
All valves are lock-wired after final testing to prevent tampering with the set pressure. Required by code in many commercial refrigeration applications.
Same-Day Shipment
Thousands of valves stocked and ready to ship same-day from Cincinnati, Ohio. Custom set-pressure orders typically ship within 1–2 business days.
800 & 801 Series Relief Valves
The 800 and 801 series cover the full range of commercial refrigeration relief valve requirements — from small pressure vessels to large compressor systems, with standard, stainless, and quick-release configurations.
Relief Valve – 800
Low capacity relief valve for small pressure vessels. ASME certified slope of 0.42 yields 9.3 lbs/min of air @ 250 PSI set pressure.
Relief Valve – 800D
Dual-port variant of the 800 series. Identical ASME-certified performance with enhanced dual assembly options for manifold mounting.
Relief Valve – 800QR
Quick-release variant engineered for fast field replacement without disconnecting system piping. Full ASME compliance.
Relief Valve – 800SS
Full stainless steel construction for corrosive refrigerant environments, ammonia systems, and food-grade cold storage.
Relief Valve – 801
Mid-capacity relief valve for medium-sized pressure vessels and commercial refrigeration compressor systems.
Relief Valve – 801DHC
Dual-handle control variant for applications requiring lockable set pressure. Meets ASHRAE 15 requirements for commercial refrigeration.
800 Series Specifications
Slope = 0.42 SCFM/PSIA — Standard Conditions [60°F, 1 Atm]
| Set Pressure (PSIG) | Air SCFM | Air lb/min | NH3 lb/min | R-22 lb/min | R-404A lb/min |
|---|---|---|---|---|---|
| 50 | 29.3 | 2.2 | 1.7 | 3.9 | 4.1 |
| 100 | 52.4 | 4 | 3.1 | 6.9 | 7.3 |
| 150 | 75.5 | 5.8 | 4.4 | 10 | 10.6 |
| 200 | 98.6 | 7.5 | 5.8 | 13 | 13.8 |
| 250 | 121.7 | 9.3 | 7.1 | 16 | 17 |
| 300 | 144.8 | 11.1 | 8.5 | 19.1 | 20.3 |
| 350 | 167.9 | 12.8 | 9.8 | 22.1 | 23.5 |
| 400 | 191 | 14.6 | 11.2 | 25.2 | 26.8 |
Where Cyrus Shank Valves Are Installed
Our relief valves are specified by engineers and contractors in commercial refrigeration systems across every industry sector.
Need Relief Valves for Your Refrigeration System?
Custom set pressures at no extra charge. Thousands of valves stocked and ready. Call us today and we'll ship your order same-day from Cincinnati, Ohio.