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To many pumps!!!
Caught oversimplifying. Two demerits. Doug is right, of course,
although in my defense I will point out that the Air Con pump is almost certainly centrifugal (and, hence, non-PD) while the washdown could be either, so my suggestion is OK. Of course, in your praise of non-PD pumps, you don't mention that they are unholy nuisances, prone to lose their prime at the slightest provocation -- I remember surfing in the Southern trades from the Galapagos to the Marquesas, a lot of air under the boat and the reefer going down every five minutes because its pump didn't like air. Changing course to pamper a pump isn't my idea of ideal. Fortunately the pump was happy to run dry, but I would have traded it for a diaphragm pump of sufficent capacity in a second. (Or why Fintry has pressurized seawater available in volume from any of three sea chests -- I love the conservatism of the Royal Navy, but that's another story). Rutuonline doesn't tell us which supply he's running the watermaker from, so you may be right there. As for, "Too logical here. Aren't you even going to call anybody names?!?", I am the voice of reason -- I don't ever call people names, even when they're flaming something-or-others (which, let there be no mistake, does not apply to Glenn or Doug). Jim Woodward www.mvfintry.com DSK wrote in message ... Glenn Ashmore wrote: ... Has anyone ever used the washdown pump as a watermaker boost pump? Jim Woodward wrote: As you certainly know, broadly there are two classes of pumps, high pressure / low volume and low pressure / high volume. I agree, although the distinction between positive displacement & nonPD is important for several reasons. Most booster pumps are non positive displacement so that they don't overpressurize the inlet side of the main pump casing. They can also supply positive flow over a wider pressure range, such as delivery to several subsystems. Another nice thing about non positive dispalacement pumps is that they can have flow through them when not running, and can readily be primed from either side. The former is good for water pressure, washdown and fire while the latter are used for bilge and sump applications. The best example of this difference is the Jabsco diaphragm pumps, where you can buy the same motor and frame driving different belt pulleys and diaphragms -- a single spare motor can back up both your freshwater and sump pumps.... Now I suspect the watermaker doesn't care much about pressure (there are so many variations today that I can't say for sure) and might even be upset if you had too much, but it does want a certain volume and minimum air. So, offhand, I'd suggest the AC cooling water pump rather than the washdown pump. Agreed, with the caveat that the AC cooling pump might be alternating current whereas Glenn might want to run his watermaker on 12V DC. But, you have a better way to make the choice -- look at the specs on the manufacturer recommended watermaker booster pump and then pick the pump you have that is closest. Too logical here. Aren't you even going to call anybody names?!? Fresh Breezes- Doug King |
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