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 ensures uncompromising quality from our Chicagoland facility.
ASME Certified
Manufactured in accordance with ASME Boiler and Pressure Vessel Code Section VIII Division I. Stamped with the ASME Certification Mark (UV Designator).
Triple-Tested
Each valve undergoes three separate test sequences for set pressure and sealing before shipment.
Custom Set Pressure
Range: 50–400 PSI in 25 PSI increments, at no additional cost. Custom orders completed in 1–2 extra days.
National Board Certified
Certified by the National Board of Boiler and Pressure Vessel Inspectors (NB Mark).
Lock-Wired Security
Prevents tampering with set pressure — required for many refrigeration applications.
Canadian Registered
Inquire about our range of CRN registered valves and manifolds ready to ship North of the border.
800 & 801 Series Relief Valves
Designed to cover the full range of commercial refrigeration applications — from small vessels to large compressor systems.
Relief Valve – 800D
General purpose version of the 800 series, pairs best with our dual manifold assemblies.
Relief Valve – 800
Low-capacity valve for small pressure vessels.
Relief Valve – 800QR
Quick-release design for fast replacement without disconnecting piping.
Relief Valve – 800SS
Full stainless construction for corrosive environments, excellent for ammonia based systems.
800 Series Specifications
Slope: 0.420 SCFM/PSIA — Standard Conditions [60°F, 1 Atm]
- Air SCFM
- 29.3
- Air lb/min
- 2.2
- NH3 lb/min
- 1.7
- R-22 lb/min
- 3.9
- R-404A lb/min
- 4.1
- Air SCFM
- 52.4
- Air lb/min
- 4
- NH3 lb/min
- 3.1
- R-22 lb/min
- 6.9
- R-404A lb/min
- 7.3
- Air SCFM
- 75.5
- Air lb/min
- 5.8
- NH3 lb/min
- 4.4
- R-22 lb/min
- 9.9
- R-404A lb/min
- 10.6
- Air SCFM
- 98.6
- Air lb/min
- 7.5
- NH3 lb/min
- 5.8
- R-22 lb/min
- 13
- R-404A lb/min
- 13.8
- Air SCFM
- 121.7
- Air lb/min
- 9.3
- NH3 lb/min
- 7.1
- R-22 lb/min
- 16
- R-404A lb/min
- 17
- Air SCFM
- 144.8
- Air lb/min
- 11
- NH3 lb/min
- 8.5
- R-22 lb/min
- 19.1
- R-404A lb/min
- 20.3
- Air SCFM
- 167.9
- Air lb/min
- 12.8
- NH3 lb/min
- 9.8
- R-22 lb/min
- 22.1
- R-404A lb/min
- 23.5
- Air SCFM
- 191
- Air lb/min
- 14.6
- NH3 lb/min
- 11.2
- R-22 lb/min
- 25.2
- R-404A lb/min
- 26.7
| 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 | 9.9 | 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 | 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 | 26.7 |
Where These Valves Are Used
Need Relief Valves for Your Refrigeration System?
Custom set pressures at no extra charge.