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I am unable to pull oil through the Anti-Syphon Valve. Part # 1, is the pump rotating in the correct direction?

FILED UNDER: Anti-Syphon Valve


I am unable to pull oil through the Anti-Syphon Valve.  Part # 1, is the pump rotating in the correct direction?

Steps to Troubleshoot

If you are unable to pull oil through the valve, there can be several reasons for this. First, check to ensure the pump is rotating in the proper direction. This can be done by turning the pump on and observing the compound/vacuum gauge at the pump inlet. If the gauge goes to positive, the pump is most likely turning the wrong way, and trying to pump back through the valve. If the gauge is going to the negative, the pump is rotating properly.


If the pump is rotating correctly, observe the vacuum reading on the compound/vacuum gauge. If the vacuum reading is excessive, (in excess of 15” of mercury) remove the spring and poppet from the valve, replace the cap and turn the pump on. At this time, there should be minimal vacuum, and you should flow oil easily. If you still have excessive vacuum, check the suction line for obstructions. If, with the spring and poppet removed, you have very low, or no vacuum, but are moving oil, you may have a valve with the incorrect spring for your application. To verify the spring size in your valve, there will be a hand-stamped number on a pad adjacent to the “TYPE A” cast into the valve. The number will be 5, 10, 15, or 20, indicating the number of feet of head the valve is rated to protect against. If for instance, there is 4 feet from the top of the tank to the center of the pump inlet, and your valve is stamped with a “15”, this would be a mismatch, and cause excessive vacuum. See Part # 2 for more on excessive vacuum.