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Air Vacuum Pumps

Postby kazzer » Fri Jul 25, 2008 9:42 am

A few people have suggested the our SNORT LPB air vacuum pump is unsuitable for use as an RCABS pump because it will not produce sufficient pressure. They suggest the Smart Vacuum pump is better. I have taken both pumps apart and they are very similar in design, having three separate mini bellows working from a single cranked shaft.

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On testing the Caswell pump, I found at 12 volts, the pump would give a pressure of 14-16psi, at 7.2 volts, it gained 10-12 psi. more than adequate for the RCABS bladders.

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Further testing showed that the smaller bladder we sell 4.5" x 2" will fill in 3 seconds, the 6.5" x 3.25" in 10 seconds and the 8.5" x 4.5" in 20 seconds.

The Caswell LPB pump has two pipe connection tubes, unlike the Smart pump which has its intake on the side, through vents, making it very difficult to connect to.

Our smaller pump has only two bellows inside, and it has been reported that this allows air to feedback over time.

I have ordered a supply of small check valves to place in line, preventing this. These units are used in saline drips, so if you want you scrounge one, next time you're visiting your pal in hospital, just snip the valve out of his line.!

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http://www.caswellplating.com/models/pumps.html
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Postby petn7 » Fri Jul 25, 2008 6:36 pm

I plan on using that pump (large one) in my RCABS-DP ballast system.

How do those "check valves" work? Like one way air valves?
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Postby kazzer » Fri Jul 25, 2008 8:39 pm

Yes, they are a one-way check valve.
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Postby Crazy Ivan » Fri Jul 25, 2008 10:26 pm

Actually Mike, a little blow-by in the pump in an R system can be a good thing if it isn't too annoyingly severe. In an all out power failure, the boat will eventually come back up. :wink:
Of course, in a straight RCABS setup, the check valve would be a "must have".
George "Crazy Ivan" Protchenko
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Postby kazzer » Fri Aug 01, 2008 9:13 pm

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Postby kazzer » Thu Aug 21, 2008 2:45 am

More stats coming in on these pumps.

The GSPV Type-GSV1412N (small 6 volt) = 17 psi and 12" vacuum. It will not re-start until the pressure drops to about 10 psi. Draws around .2 amps at it's maximum.

The GSPV Type-GSV2512/V (larger 12 volt) gets 12 psi and 12" vacuum. No load at 12 volts the current is .14 amps and it works equally well at 6 volts and draws .11 amps with the same pressure and vacuum. Probably a little slower to build pressure. At full load the current drops to about .1 amps at 6 or 12 volts.

Data from Larry Kuntz.

Thanks Larry
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Postby Sub culture » Thu Sep 11, 2008 5:48 am

Hi Mike,

Do you have the spec on this little waterpump you stock?


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Need to know the flow rate.

Cheers

Andy
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Postby mickelsen » Thu Sep 11, 2008 6:50 am

Mike,

Are you saying that the smaller pump produces 17psi and that the larger pump produces 12psi? That seems just backwards. Shouldn't it be the other way around?

Mark
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Postby Larry Kuntz » Thu Sep 11, 2008 9:06 pm

Hi Mark,
Mike handed me two pumps to test and these are the results I got. Don't know how consistent they are from batch to batch. The only measurement I did not take was volume. I would guess the larger had a higher flow than the small one. Not sure though.
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Postby mickelsen » Fri Sep 12, 2008 2:45 am

Thanks, Larry. I just wanted to make sure. Those are very interesting findings.
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Postby Sub culture » Wed Sep 17, 2008 2:59 pm

deleted.
'Why are you staring at an empty pond?'

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