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The check valve from Extreme Outback arrived mid-week. I had gotten an e-mail from George earlier in the week stating that they had mistakenly missed notifying me (of the SEMA induced delay) about my order and offered to ship the order for free. I responded that it was not necessary but when the valve arrived, the invoice showed free shipping. Thanks Extreme Outback for great customer service!
The check valve is a one way valve. Air can flow through the valve in one direction but is blocked from flowing in the opposite direction. The check valve is installed between the output port of the compressor and the air tank such that the air can flow out of the compressor but not back into it. This is done so that once the air tank is filled and the pressure switch turns off the compressor, air in the tank can not leak back into the compressor and bleed down the tank. It also allows pressure in the compressor cylinder to bleed off (naturally) which makes it much easier for the motor to start later on since it has no head pressure to push against.
The check valve allows air flow in the direction of the arrow that is stamped on one of the wrench flats. Be sure you pay attention to which way your install the valve. Putting it in backwards (against the air flow) will certainly cause much grief for your compressor (and possible damage). The valve comes with a brief instruction sheet that cautions against over tightening the end with the white plastic X. Too much and it will break the valve. I used Teflon tape on both ends of the check valve.
As with the other air fittings, I applied Teflon tape to both sets of threads on the check valve. I removed the 3/8" hose from the 90 degree elbow at the inlet of the air tank and threaded the check valve into the elbow. I then threaded a female air hose barb fitting onto the check valve. The air hose was slipped onto the barb fitting and a small hose clamp was used to secure the hose in place.
After the tank was filled, I disconnected the compressor's end of the hose. I couldn't detect any air flowing out which meant the check valve was working. An overnight test revealed that it did indeed work very well. The tank was still full when I checked it.