Sub Driver (aka WTC) On-Board Propel Gas Bottle

[corsaire]

Guys,

Do any of you can tell how do you know when the on-board gas bottle is completely filled out?

Thanks

Corsaire

[thor]

Of course, you fill the onboard tank with the can of refrigerant turned upside down to assure you are filling with liquid and not just vapor. The pressure will equalize quickly. It takes only a few seconds for the tank to fill. Do a quick test by pressing the stem down on the schraeder valve. A bit of liquid will spray out. You now have a full tank.

[salmon]

Just to add to this, it may also help to do a pre freeze of the on-board bottle. Just do a quick fill, then as Matt suggested push the schrader valve down to release the gas (of coursed use screw driver or forceps to protect skin), this will pre-chill your bottle, then fill again with a regular fill.

As far as knowing when it is completely filled out? Experience would be my answer. I can see how my sub will sit in the water or if I get a good connection when filling. I suppose the more practical way is to weight the sub before filling and then after filling.

[wlambing]

Tom has offered sage advice! Always pre-chill and refill!!

[thor]

Oops! It's been so long since I used one of those units that I forgot that very important little trick.

[PaulC]

Tom is correct. You'll get a much better fill by doing that. In the end, there's no way to gauge for sure if the Propel tank is "full". However, over time you'll be able to accurately gauge when it has been charged properly for a patrol, and how many blows you'll get from that type of charge.

Having run gas ballast systems for many years, including a D&E WTC-3, I have found that a "full" tank isn't really necessary apart from trim purposes. I prefer to run submerged and would only command a handful of blows on any given run -- more than covered by an average charge. Usually an end of run surface to come in to port would be the only real blow requirement. With that being said there is great comfort knowing you can blow everything in an emergency (haven't we all been there?).

A final note on the topic is the end of run inverse. Make sure you fully vent the Propel tank when packing up to go home. Unscrew the Schraeder valve as well. Sitting on the bench, or in the car, will cause the tank to warm and can result in an over-pressure situation if part of the charge remains. As a result you can pop a hose in the D&E ballast setup, which is their designed failsafe for over-pressure, or worse if your system doesn't have a pressure relief mechanism. Learned that the hard way too!

[corsaire]

Great feedback. Thank you all. And while we're at it talking about "gas pressure safety hose" - Is this the hose size you would get Clippard as a back up supply? Just making sure it is the rigth size.Thanks.

[corsaire]

With propel gas I've also noticed that we lose like a 1/4 can or so because of lack of pressure which it seems to get lost as the gas is used up. I've tried to used up that last 1/4 of gas, I thought I got it in the gas bottle in the WTC only to discover later bottle had barely gas left for one blow.

[PaulC]

That looks like the gray hose that came in my WTC-3.

[bob_eissler]

Make sure you hold the can upside down to get the liquid into the gas bottle. The adapter might be losing some gas if you leave it attached. You shouldn't be losing any where near a quarter bottle. I save almost empty cans for testing in the pool.