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Air Head, or not under pressure to perform...
Well, as another thread has reflected, I finally finished my PVC
outflow installation on the forward head. This is a Raritan PHII, recently rebuilt and, just before installation, regreased with teflon grease, so I have excellent confidence in the pump. It also has a recently serviced air intake valve, which I tested in the course of the test below. It performs properly. Because I haven't yet obtained (later today) the intake hoses, I just filled the bowl from the shower hose. Moving the selector to "dry" I pumped it out. Everything went just fine. Until, after I quit more than a dozen strokes after the noise indicated the last of the water had been removed from the pipe under the stool (the flapper opening on intake, then closing on pump), I heard the water cascade back down into the area of the joker. Based on several threads, both recent and long ago, I had *thought* (after an annoyingly high number of confirmation questions in a long-ago thread, because my [limited] physics understanding refused to believe it) that you could dry pump all the liquid out of the standing part of the vented loop. That thrilled my engineer-ish nature because I could leave everything except the waterline level of seawater dry each time, if I just took the time to dry pump each flush. Despite my having, now, PVC, which should never smell, I like the thought that my lines would remain dry and un-encumbered by scale. Back to the dry-out process... Evidently I'm doing something wrong, because it doesn't. Trying it "wet" (not wet because I don't have the lines, and I'm not in the water if I had) didn't make any difference. Pumping wildlly (perhaps 2-300 strokes per minute rate) didn't change matters. I still assume I'll be able to push everything out of the pipe below, as, once the fall has occurred, and the anti-syphon has let in the air to take up the space, the next stroke should pressurize it, leading to the air bubble going all the way to the through hull. Our marker for success will be to have the t/h bubble (I'm sure there is a quantified number of strokes that this will take, and we'll have to wait until we're in the water to determine that number), and will become our standard for final flushes. However, I can't get rid of the standing water. What am I doing wrong (or, is there an equipment problem?) such that I can't pump the standing water out? L8R Skip Morgan 461 #2 SV Flying Pig KI4MPC http://tinyurl.com/p7rb4 - NOTE:new URL! The vessel as Tehamana, as we bought her "Believe me, my young friend, there is *nothing*-absolutely nothing-half so much worth doing as simply messing, messing-about-in-boats; messing about in boats-or *with* boats. In or out of 'em, it doesn't matter. Nothing seems really to matter, that's the charm of it. Whether you get away, or whether you don't; whether you arrive at your destination or whether you reach somewhere else, or whether you never get anywhere at all, you're always busy, and you never do anything in particular; and when you've done it there's always something else to do, and you can do it if you like, but you'd much better not." |
#2
posted to rec.boats.cruising
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Air Head, or not under pressure to perform...
Skip Gundlach wrote:
Because I haven't yet obtained (later today) the intake hoses, I just filled the bowl from the shower hose. Moving the selector to "dry" I pumped it out. Everything went just fine. Until, after I quit more than a dozen strokes after the noise indicated the last of the water had been removed from the pipe under the stool (the flapper opening on intake, then closing on pump), I heard the water cascade back down into the area of the joker. Based on several threads, both recent and long ago, I had *thought* (after an annoyingly high number of confirmation questions in a long-ago thread, because my [limited] physics understanding refused to believe it) that you could dry pump all the liquid out of the standing part of the vented loop. Yes...you should be able to, provided the toilet is working anywhere near spec and the lift doesn't exceed about 4' (6' horizontal). So one or more of 3 reasons isn't letting you do it. 1. Your vented loop is higher than the toilet can lift it. 2. The lift is marginal, a dozen pumps aren't enough. 3. You tried to save money by buying a used PH II on eBay that's turned out to be so old and worn--or the inside of the pump cylinder is so scratched and scored by grit and salt--that new seals and o-rings can't bring it back to specs. Evidently I'm doing something wrong, because it doesn't. Trying it "wet" (not wet because I don't have the lines, and I'm not in the water if I had) didn't make any difference. It wouldn't...the only thing that "wet" does is allow flush water IN...it has nothing to do with discharge. Pumping wildlly (perhaps 2-300 strokes per minute rate) didn't change matters. That actually defeated what you were trying to accomplish 'cuz flailing only "aerates" the discharge. Slow deliberate pumping is FAR more efficient. I still assume I'll be able to push everything out of the pipe below, as, once the fall has occurred, and the anti-syphon has let in the air to take up the space, the next stroke should pressurize it, leading to the air bubble going all the way to the through hull. What air bubble??? The air valve in the vented loop only brings air into a line through which liquid is being PULLED...it doesn't do a thing in a line through which anything is being pushed. So there is no "air bubble" in the dishcarge line. The vented loop is only there to prevent the SEA from starting a siphon back into your toilet...it doesn't have anything whatever to do with flushing a toilet. I'm beginning to wonder if ANYone knows how a vented loop works! Our marker for success will be to have the t/h bubble (I'm sure there is a quantified number of strokes that this will take, and we'll have to wait until we're in the water to determine that number), and will become our standard for final flushes. No...your "standard for final flushes" will be the number it takes to move bowl contents from the bowl to their final destination...or at least over the top of a vented loop if it's all downhill the rest of the way. However, I can't get rid of the standing water. What am I doing wrong (or, is there an equipment problem?) such that I can't pump the standing water out? You're always gonna have a little left in the line to run back downhill. The joker valve should reduce it to slow seepage, but it won't keep it out of the bowl entirely. I suggest you give Vic Willman at Raritan a call: 800-352-5630 x 6. -- Peggie ---------- Peggie Hall Specializing in marine sanitation since 1987 Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and Other Sources of Aggravation and Odor" http://shop.sailboatowners.com/books...ku=90&cat=1304 |
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