Air Operated Unloader Valve


The model 907 unloading valve uses a low control pressure to shut off a high pressure line such as on the discharge of a compressor. When control pressure is released, the valve opens. A minimum of 70 psi control pressure is required to operate the valve at 6000 psi. Control pressures up to 5000 psi can be used without affecting operation or damaging a valve. One application for the valve is to unload a compressor upon shutdown. Interstage pressure could be used as the control pressure. Also works on automatic condensate drains for compressor separators, like the Coltri MCH6.


Typical Applications

  • Unload his pressure interstage and discharge lines upon shut down
  • Automatic condensate drains for compressor separators, like the Coltri MCH6
  • Control of high pressure lines using low pressure air and inexpensive low pressure solenoids
  • Numerous other control and logic functions
  • Process industry control of liquids and gases
  • Air tank fill stations


Type Unloader Valve
Hand Loaded/Operated or Dome/Air Operated Air Operated
Maximum Rated Pressure 6000 psi
Inlet Port Size 1/4 in MNPT
Outlet Port Size 1/8 in FNPT - must vent to atmospheric pressure
Control Port Size 1/4 in MNPT
Maximum Differential Pressure 6000 psi
Outlet Pressure Rating Atmosphere
Maximum Control or Dome Pressure 5000 psi
Leakage Bubble tight
Flow Coefficient (Cv) 0.05 (equals 0.06 in orifice)
Actuating Pressure 70 psi at 6000 psi inlet
50 psi at 4000 psi inlet
25 psi at 2000 psi inlet
Minimum Temperature -15°F
Body Material Anodized aluminum
Internal Materials Brass, Stainless
Seal Materials Kel-F, Nylon, Viton
Weight 7 oz (200 g)
Overall Length 3.5 in
Round Diameter 1.5 in
Repair Kit 907-14
Special Note 90 micron inlet filtration