Guys......the design of these single action piston pumps is via the
pressure energised O-ring on the piston rod...[or in the gland in other builds]...
If you are pumping to an atmospheric tank, the O-ring does not energise and simply relies on friction or stiction to transfer the fluid...[the friction is also created by the force to transfer the single slug of water and any such pipe/tube friction losses which in our cases are negligible ]
The difference between pumping water at zero pressure and pumping water with
a mix of oil at zero pressure is lubricity related ie., water having a lower lubricity
So the experience offered by coolbumble below is not a fault of the pump
The O-ring must be deformed...ie., pressure energised to perform the drip tight transfer of fluid...... such O-rings will happily perform against far greater boiler pressures that we contemplate
O-rings are used as dynamic piston seals in millions of industrial applications where oil hydraulic fluid is the medium ...so have no fear of the humble O-ring
The as supplied 0-rings in my two pumps are
green or a VITON elastomer which has a low tear and abrasion resistance and should ideally be replaced with standard NBR or nitrile O-rings which are totally compatible with raw water........
Without getting too far off track, an O-ring any application requires clean fluid to maintain both it self & the pump bore
A single grain of sand [silica] can be far harder than the bronze pump bore or stainless piston.....that grain of sand embedded around the O-ring will score the pump bore and render it as useless as the scored bore will shred the O-ring and cause water bypass......
Some members [Jerry C] is/are fortunate to steam on pristinely clean water.........others who are not should consider a form of water pump suction filtration ....or consider on-board water makeup tanks......Derek
