Compressor to fill Propel Ballast Tanks - Can we save money?

[wintermute]

With the WTCs sold by Dave Merriman, SWM, etc., is there an alternate way to fill the ballast tank (i.e. with air using a compressor or bike pump)? what psi do you need to get a decent amount of blows?

[Guest]

It's a different principle to

It's a different principle to the gas systems used on the D&E and SWM wtc's.

If you want to see examples of using compressed air instead of compressed gas (ie. propel, butane etc.) then do a search for RCABS.

Andy

[wintermute]

The BASIC difference is that

The BASIC difference is that the D&E and SWM systems are high pressure (and limited supply) and the RCABS is low pressure (and recirculating), correct? There's a billion little differences, but they both use a gas. Does it matter if it uses air (as in the RCABS) or methyl-ethyl deathyl (as in the D&E and SWM systems? What is the typical gas pressure in a fully charged pressure vessel that uses Propel? If I can charge the sucker w/ my bike pump, I could maybe get it up to 130 psi. If I use my handy-dandy compressor for pumping up my Jeep's tires after being on the beach, I can maybe get up to 260 psi (although that would probably turn the thing into a bomb).

[Guest]

You don't need to make

You don't need to make a bomb. The big difference is that in the RCABS the gas, (air) is RECIRCULATED and reused. That way, you don't need a high pressure supply tank, nor do you need to replenish your gas supply. The air pressure produced by the small DC pump is only about 11psi, but it is enough to bring your model back up from about 20 feet deep, as many times as you want, assuming you have adequate battery power. RCABS = Recirculating Compressed Air Ballast System.

[wintermute]

Thanks Art. That is what

Thanks Art. That is what I suspected. I'm a newbie here, but I have to say that you've come up with a very eloquent system - one that I hope to implement sometime. But, being a newbie, I wouldn't dare retrofit a system. Some of the initial models that I am looking at are ThorDesign / Atomic Subs and SWM models. As I understand it, they are made to accept M&E and SWM WTCs, respectively, w/o any modification. Since both of these WTCs use the high pressure systems (which are charged w/ Propel via a Schraeder valve), why not hook a simple bike pump or compressor up to the pressure vessel to charge it. The only question is, what psi should the vessel be filled to?

[tsenecal]

I am not sure you

I am not sure you guys fully understand how the propel systems work. you don't fill the propel pressure cylinder with gaseous propel, you fill it with the liquified propel. the propel cylinder in my SWM blueback is only a couple ounces in size. it is a copper pipe 1" in diameter and 2.5" long. I don't think you could fill it with enough compressed air to get more than 2 or 3 cycles of gas. The robart compressd air systems used in model airplanes have significantly larger air tanks (like 10 times larger) and they are used only for small landing gear actuators, not large ballast tanks.



Edited By tsenecal on 1145655099

[mike dory]

Guy's -- The pressure in

Guy's -- The pressure in Propel is 70 Lbs. per Square inch at 70 F. However, Propel expands 400% going from a liquid to a gaseous state That's why a small tank of propel dosen't need real High pressure like say Co2 which is around 2800 Lbs. per square inch and requires a regulator in order to be used in our application. Best Wishes Mike Dory