HP Pump pulsates bad on rinse, works fine on soap.

[Dan-Ark]

The one Hypro pump that I left in the wash i put back on line last year seems to have developed a problem. This is a D&S pump stand, the rinse comes from a tank mounted above the pumps. Soap uses hot water coming in under city pressure. there is a large check valve under the tank (one for each bay) I suspect that is my problem and I couldn't find the one I replaced needlessly last year so have to order. Also noticed on this pump stand the rinse feeds through a T below the pressure releif valve, so exess pressure dumps into the gravity fed line. My three other bays use a long hose that makes a loop before reaching the pump. this bay has about 6" of hose. Could there be too much turbulance so close to the pump? It was working fine and started pulsating while I was washing down the bay. It does pump some rinse water, just not full pressure and not steady so if it is the check valve, it would have to be restricting the flow but it is not stuck. It holds the water back when I take the hose off. Now I wish I had tried the longer hose before I left the site tonight. I also wish I took a picture as my fingers are getting tired trying to come up with a thousand words instead... Am I overlooking anything else to check? TIA.

 

[MEP001]

There's probably not enough flow to the pump on rinse. Loss of pressure on one function is either insufficient flow or air entering the line. If you can have someone switch between the functions so you can listen to the pump, see if it clatters really loud (cavitation from lack of flow) or just drops in pressure (air leaking in).

 

[mac]

Well since your soap and wax are fed by pressurized hor water, and rinse is sucked through the check valve, I suspect that.

 

[Dan-Ark]

thanks guys. Today I replaced the feed hose from the rinse tank, added a looped hose between the Pressure valve and the pump (this is the only one of 4 that did not have a looped 20" or so length of hose, it had an 8" long piese of hose. I also noticed water dripping from the soap line and found that check valve not working so replaced it. Its still a little noisy but it maintaines a constant pressure now, same as it was since we opened last fall. I do have the 1" check valve on hand now but seems to be getting plenty of water now.

 

[Jeff_L]

Interesting....not sure how adding a longer hose solved your problem. I would have thought the check valve was bad and restricting the flow of water to the pump causing it to cavitate.

 

[Dan-Ark]

I don't know if it affected it. Might have had a pin hole in the hose from the tank to the pump. there was a small rub area, but I didn't see a hole. the looped hose just maches the other 3. I figured someone did it for a reason. Without it the pressure relief valve dumps into the supply line jsut before entering the pump. I was wondering if the turbulance of the PR valve water was creating some sort of cavitation in the pump. Could also have been pulling air from the soap line. that check valve was definately bad I I did see a couple drops of water on it before I started the repairs. Unfortunately, instead of doing one thing at a time to see what worked, I sort of shotgunned it so now will never know what, if any of the things I changed, had any effect.