As far as I can tell the difference between the Johnson WD (wash down) and WPS (water pressure system) is only the settings on the pressure switch. The WD has a cutoff pressure of 70 psi while the WPS cutoff is 41 psi. This means that when you stop the flow of water
the WD will charge your pipes and hoses to 70 psi. Unless you have a very large accumulator this 70 psi will immediately dissipate once you open a hose and you will get exactly the same flow that the WPS system would give you. Can anyone offer a reason to pressurize your system to 70 psi when the only time you will experience that pressure is for a fraction of a second? Additionally, after closing the hose valve, it seems to me that the pump
will run longer in its most inefficient range thereby wasting power.
The reason I ask is that I need to purchase
some of these as washdown pumps and it seems to me that I should buy the WPS with its lower pressure shutoff. If I am wrong, please explain why.
BTW, I know that some of the WD pumps are packaged with strainers, hoses and sprayers but I do not need those. I am only thinking about the pump