Harvard wrote:
RLS7201 wrote:
So much nonsense about check valves in water pumps. There are NO check valves in water pumps. There are inlet valves and outlet valves. Both an inlet valve and an outlet valve would have to fail for water back flow to the fresh water tank.
Richard
In the water pump that I have disassembled there was only rubber flapper valves (as I recall 3 in PARALLEL). When that pump cycled through the pumping STROKE it pushes water through and opened the flappers. When the pump cycle is not in the pump STROKE cycle the flappers would be closed to prevent back flow. I am not saying all pumps are like my ShureFlow. And yes, in my case, there was grit preventing one of the flappers from closing that allowed back flow when the pump was off.
There's actually the 3 plus one in the center. I assume there are 3 on the inlet side since it's pulling water under a vacuum. The pump stroke pulls water through the 3 then they close as it pushes water back out the center one.
The single valve prevents water from being drawn back into the pump from the pressure side on the vacuum stroke. The other 3 prevent water from pumping back into the tank on the pressure stroke.
