How to inject soap into HP pump

[Washmee]

I have a number of HP pumps that all draw from the same gravity feed tank. One is for my chassis bath, another for mat cleaning and one is for my prep gun. I would like to inject soap into the prep gun pump only. Any suggestions?

 

[MEP001]

The easiest way is to dilute the soap in another tank and just tee it into the pump inlet. You can inject it downstream, but you'll lose pressure.

 

[Washmee]

I don't think injecting the soap through the pump inlet will work for my application. I use an unloader that returns the water to the holding tank when there is no gun being used. How much pressure would I lose by injecting downstream from the pump?

 

[MEP001]

Depends on the injector, but usually around 20%. I tried a Dema stainless 203 and it took away about a third of the pressure before it would inject.

I've seen some prep pumps set up with their own tank that supplied the soap already mixed with the fill valve so bypassing the unloader back to the tank wasn't an issue.

 

[Washmee]

Depends on the injector, but usually around 20%. I tried a Dema stainless 203 and it took away about a third of the pressure before it would inject.

I've seen some prep pumps set up with their own tank that supplied the soap already mixed with the fill valve so bypassing the unloader back to the tank wasn't an issue.

It looks like that's the way I will have to go.