Hi all,
know there are lots of threads on this subject, but thought this might be of help to someone.
just bought a screen pump from Halfords, their universal washer pump, ref HWP1, 12v at £ 14.99.
decided to carry out exhaustive testing to see how suitable it would be for filling and emptying my ballast tanks, and possibly as a bow thruster.
testing proceedure.
1 take four coffee cups.
2 take one and turn upside down on draining board. designate as cup 2
3 take two more cups and place right way up either side of cup 2. designate as cups 1 & 3
4 half fill cups 1 & 3 with cold water.
5 take last cup, place two spoonsfull of sugar and one of coffee, part fill with boiling water, add milk. designate as my cup
6 fit two leads to the pump and place on top of cup 2 with short pipes from the outlets / inlets into cups 1 & three
7.touch leads to the connectors on a 6v battery. water transfered from cup 1 to cup 3.
8. reverse leads at battery, water transfered from cup 3 to cup 1.
9. finish coffee and clear all away before SWMBO comes home.
seriously, I could not tell any difference in the flow rate between the two directions, and even on 6v flow was quite fast.
I did not prime the pump at all, and although it was well above the water level it immeadiately primed and started pumping.
hope this is of some use to someone, off to work out wiring and piping for my ballast tanks !
cheers
alan