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Deflating the RCABS bag - rubber bands + vacuum?

R/C Submarine modelers

Deflating the RCABS bag - rubber bands + vacuum?

Postby Slats » Sat Apr 11, 2009 8:32 pm

Was wondering what is the method people use to deflate the RCABS bag.
Am using the Clippard valve on the bench for this task, and it seems very slow. Does mounting all this gear in the WTC and the vacuum created for bag inflation add to deflation?

I also tried using one of the little Caswell 7.2 v pumps to deflate the bag instead of the clippard valve - that worked very well.

What is the preferred method?

J
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Postby petn7 » Sat Apr 11, 2009 9:45 pm

I don't use anything and the bag deflates just fine with help from the vacuum.
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Postby Albion » Sun Apr 12, 2009 4:03 am

A little off topic but any idea what pressure they develop? thinking out using one in a reverse RCABS
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Postby Lobo » Sun Apr 12, 2009 11:48 am

petn7 wrote:I don't use anything and the bag deflates just fine with help from the vacuum.



Same here. I use a schraeder valve controlled by servo, no rubber bands to assist. I do use a rubber band around the leading edge of the bladder to keep it into place (snug against the wtc).
The vacuum within the cylinder created at bag inflation does a nice job of sucking the bladder air back into the wtc. If this process is happening too slow for you, I can think of 2 possibilities:

1). too much restriction on bladder air return line
or
2). too much volume of air left in wtc after bladder is inflated. Maybe you have too little or no vacuum in wtc after bladder inflation. Bladder too small?.....wtc atmosphere compartment(s) volume too large?
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Postby Art Broder » Sun Apr 12, 2009 2:41 pm

Posted: Sun Apr 12, 2009 11:48 am Post subject:

--------------------------------------------------------------------------------

petn7 wrote:
I don't use anything and the bag deflates just fine with help from the vacuum.


Lobo wrote:
"Same here. I use a schraeder valve controlled by servo, no rubber bands to assist. I do use a rubber band around the leading edge of the bladder to keep it into place (snug against the wtc).
The vacuum within the cylinder created at bag inflation does a nice job of sucking the bladder air back into the wtc. If this process is happening too slow for you, I can think of 2 possibilities:

1). too much restriction on bladder air return line
or
2). too much volume of air left in wtc after bladder is inflated. Maybe you have too little or no vacuum in wtc after bladder inflation. Bladder too small?.....wtc atmosphere compartment(s) volume too large? "

Art here: I agree with the above except for answer #2. I feel the usual reason for INCOMPLETE emptying of the bladder is a leak in WTC. The usual reason for SLOW, but complete emptying, could be #1 above, or the use of a Clippard valve instead of a servo controlled Schraeder valve.
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RCABS- It's easy to control your own bladder!
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RCABS 7.2 air pump to empty the bag instead Clippard Valve?

Postby Slats » Mon Apr 13, 2009 12:18 am

Mucking around on the bench with some RCABS gear, and decided instead of the clippard valve I used a small Caswell 7.2 pump.

The pump seems to act as useful check valve to hold the bag inflated - and then running the pump the bag deflates very fast....has anyone tried this in lieu of the Clippard valve?

J
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