[john aitken]

I have a 500 psi pump [pump tec ] I think ..when I turn it off .. then back on I have to prime it before ill work ,,any ideas don't think ..theres any loss in pressure

[Mike Halliday]

The solution might be  falling back into the tank, fit a check valve to stop back flow.

If you imagine Turning off your machine, the pipe that feeds the pump will be full of solution if this solution flows backwards back into the holding tank then once you restart the pump it has to suck air until the solution flows back up the pipe, a check valve stop the backward flow 

[Robin Ray]

The solution might be  falling back into the tank, fit a check valve to stop back flow.

If you imagine Turning off your machine, the pipe that feeds the pump will be full of solution if this solution flows backwards back into the holding tank then once you restart the pump it has to suck air until the solution flows back up the pipe, a check valve stop the backward flow 

Never thought of doing that, good idea 

[Mike Halliday]

Just a side note.... this is only the case if the pump is higher than the water supply, if the water is gravity fed into the pump it should stop it happening but I think a check valve (which only allow the water to flow one way) is always a good idea on supply hoses it should stop the need to bleed air from solution lines

[john aitken]

The solution might be  falling back into the tank, fit a check valve to stop back flow.

If you imagine Turning off your machine, the pipe that feeds the pump will be full of solution if this solution flows backwards back into the holding tank then once you restart the pump it has to suck air until the solution flows back up the pipe, a check valve stop the backward flow

      its gone ..however the problem with what your saying is it would be pressurised all the time .. 

[Mike Halliday]

The supply hose has no pressure, it is open ended at the water tank, you only get the pressure after water leaves the pump. The hose that feeds the pump has either a negative pressure (if the tank is lower than the pump) or a slight gravity supplied pressure (if the tanks is above pump)

it's the supply hose that I'm referring to when I suggest a check valve