HP Soap not drawing

[APW]

My 5CP Cat pump will not draw soap unless I valve down the gravity water tank till the pump cavitates then the HP soap is fine. If I adjust the water till the pump smooths out the soap is too weak. I have replaced the kip solenoid and hoses. I have even taken the outlet side of the kip off while HPS is running and it comes out fine. Only thing left is the pump. Could it be the pump? The pressure is fine at 1200 psi. The other three bays feed off the same soap tank and they all work fine.

 

[cantbreak80]

Measure the soap flow from a working bay’s solenoid and the problem bay.

Same? It’s not unusual for 310s & 5CPs to require throttling the water supply...especially if they are plumbed with 3/4”.
I’ve plumbed gravity feed pumps with 1/2” inlet hose & fittings for 30some years with no noticeable durability issues.

Not same?
Metering valve might need adjustment.
Or, you might have a tiny air leak in the inlet plumbing.

 

[APW]

I don't have flow meters and the kip is a non metered. The tubing is 1/2". There is a separate 3/4" spot free hose that T's in that I forgot to check. Maybe the spot free solenoid is leaking through diluting the product.

 

[MEP001]

Isn't the hose 1/4" ID push-lock from the tank to solenoid to pump? The flare fittings they use will crack and allow the pump to draw air instead of soap. Throttling the water supply just makes it draw more air and run rougher.

 

[APW]

I'll replace the fittings and see what happens. Thanks guys.

 

[MEP001]

Take them loose from the solenoid and look inside. If the flare is cracked, you can see it.

 

[APW]

I took all the low pressure hoses off and none of the fittings are cracked. I valved down the gravity water until the pump cavitated and then it started drawing soap. I ended up turning the pressure down from 1200 to 1100 psi and the pump smoothed out and started drawing soap with the gravity water valved back. What you reckon?

 

[MEP001]

Is there any check valve on the soap line? I haven't worked on one of those in a couple years, but I think I remember removing check valves and swapping the in/out on the solenoids to eliminate the need for check valves. I just did the same on a bay at someone's wash where the check valve had come apart and it was stopping flow.

 

[APW]

There is a check valve but not on the soap line. It is right past where soap, wax, and spot free tie together. It's a 3/4" check valve that reduces to a 1/2" hose to the pump.

 

[cantbreak80]

Doesn't the Ultra VFD system feature pressurized cold water rinse? Could it be that the cold water solenoid for the problem bay is not fully closing?

 

[APW]

It does. I valved off the cold rinse while running HP Soap but it didn't make a difference.

 

[cantbreak80]

OK...I'm running out of ideas.

Is the wax delivery affected, too? Or just soap?

Looking at the Ginsan flow diagram the only other water feed is the SFR solenoid. Maybe it's not fully closing?

 

[APW]

I took the hose off the spot free last night and nothing came out of the solenoid so that rules that out. It seems to be working now that I turned the pressure down to 1100 from 1200 psi. I did not check the HP Wax but that's a good idea to check it also.

 

[Randy]

We don’t use the gravity fed water tank system at our car washes, we reduce the city water pressure down to about 10psi. On our chemical inlet side we use a DEMA injector. I wonder if a DEMA injector might solve your problem.