Cavitation in one bay

[washme1]

I think I'm using the right term, capitation, for loss of pressure and high turbulence in one of my ss bays. Only affects hp soap and wax, not rinse. Seems to happen after about 5 seconds when I change from rinse to soap, just as the soap or wax reaches the bay. I tried momentarily turning off the soap valve to that bay which did not help.

 

[PaulLovesJamie]

capitation isnt so bad, its de-capitation you want to avoid at any cost.

 

[PaulLovesJamie]

sorry, I couldnt resist; cavitation is the word you're looking for.
If it is cavitation then you are getting air in the lines somehow. That can be hard to find, start by making sure all fittings are tight.

A couple questions - is it every bay? Also, is your rinse pressurized? Is the soap/wax gravity feed? Does the soap/wax T in before the pump or after the pump?

 

[washme1]

sorry, I couldnt resist; cavitation is the word you're looking for.
If it is cavitation then you are getting air in the lines somehow. That can be hard to find, start by making sure all fittings are tight.

A couple questions - is it every bay? Also, is your rinse pressurized? Is the soap/wax gravity feed? Does the soap/wax T in before the pump or after the pump?

It's only one bay. Rinse is not pressurized. Soap/wax is gravity feed, T is before the pump.

 

[MEP001]

Actually cavitation is caused by a restriction of water to the pump. Water under enough vacuum boils at room temperature, then it becomes a gas in the pump.

Since it takes a few seconds for the loss of pressure it does sound like a leak in the plumbing allowing air in. If you don't see an obvious leak anywhee, start by checking any lines that are higher than the pump. A usual culprit is hose/tubing going to the soap and wax solenoids that are mounted to the undersie of the electrical cabinet above the pump.

Are you certain there isn't a rinse solenoid? The usual reason such a problem would go away on the rinse position is because the supply of pressurized city water to the pump prevents it from drawing air through a leak. Do you have separate hot and cold supply gravity tanks? What switches between hot and cold water?

 

[washme1]

I got the issue resolved without de-capitating myself. It turned out to be a bad check valve ahead of the high pressure functions.

 

[Randy]

It usually something very simple, like a check valve or a stuck solenoid valve.

 

[Plow Guy]

Just happened

I have been having a pressure drop in my good pump at my wash on my wash cycle, about 200 psi.Over the last few days I have replaced 1/4 inch poly pipe and push connectors. I still had a few bubbles through my ounces per minute site gauge, I rinsed my screen at my hydro minder soap tank.This took care of the air problem,pressure dropped more to 300 pounds.Very hard pulsing.I checked my cold water supply by taking the fitting off at the pump, dropped it to the floor, good flow. When I turn the cold cycle on in the bay, the supply line, a clear plastic hose with a steel coil, did not leak.On the cold cycle this line will pressurize from the pump back to the hot water tank check valve.Opened the lid on the tank, could not see any back flow.I disconnected the hose from the check valve for a finical check of the valve. Removed valve, valve good. At this point I noticed a small bulge in the supply hose. The supply hose, about a year old had delaminated.When the pump created vacuum on the wash cycle, the feed hose collapsed. Problem solved. Pete

 

[pitzerwm]

It's called good trouble shooting.