Reuse Helium Gas

[commandermike]

I live in the Philippines and we are about to start flying RC blimps in different cities around the country. Here helium is about $100 per k cylinder and only available in a few key cities.

Has anyone ever tried to re-compress helium from a blimp back into a cylinder, instead of venting it out and refilling with new gas? As we plan to travel between islands, it will not be cost effective to try and ship an inflated envelope, nor can we afford to vent gas and refill, everytime we change venues?

I am thinking using an air compresor (normally used to fill scuba tanks) to re-compress the helium gas each time we pack up... but would appreciate some inputs before we do.

[GHarvey]

Commandermike,

I do not have any experience doing what you suggest, but it should work. I am a scuba diver and some compressors are used for various gas mixes including heliox which is a helium and oxegen mixture. Scuba tanks are probably readily available in the islands, so I'd try putting the helium into a spare scuba tank instead of trynig to go back into the original. That way if it doesn't work, you havn't messed up your source tank.

[Ken-Ohki]

I dont know this for sure, but the cost of the compressor you will need to recompress the gas will probably outweigh the cost of several tanks.

Ya might try local florists to supply your gas on a case by case basis, then rely on your bottle of gasfor places that dont sell baloons.

[Guga]

CommanderMike,
Helium gas once is decompressed from the cylinder degenerates at a rate of 3% a day minimum, depending on the metereological conditions, that is why it is not wise to try to recuperate the gas once it is in use.
This has been informed by the engineers from AIR Products In the helium data sheet,
Best regards M.Franco

[Guga]

CommanderMike.
Yes unfortunately the hellium gas literaly rottens (or it gets contaminated) at a rate of 3 to 5% a day depending on several temperature, moisture, changes in atmosferic pression and other factors. Even if you would put it in a glass container, or even in the vaccum of space.
The cheaper would be to use Hydrogen, this one does not degenerate, but as you know it has a terrifying condition to explosion when mixed with oxigen.
Regards , M. Franco

[galaxyrpv]

Here is my 2 cents on helium digression. From what I have experienced, and what makes since to me, is that we are all using balloon grade helium, which is not pure helium. What happens is the pure helium seeps through the bag material and leaves the impurities behind thus lowering lift capacity even after the bag is topped off with fresh helium. The bag becomes essentially a filter. I have to purge my outdoor blimps once every 2 to 3 months, this is determined when the blimp will no longer ballast correctly after being topped off. The purge procedure consists of topping of the bag and letting the helium settle for about an hour. Then I vacuum about a 1/3 of the volume from the lowest point, and refill the bag with fresh helium. This removes all the impurities and the blimp is back to original lift capacity.

As far as the pump goes, I have talked to several pneumatic pump companies and the main problem is it is difficult to pump any gas substance without air contamination, especially under high-pressure applications. Most gasses that are pumped are not affected by air contamination. What I have been told over and over is that there is not enough of a demand to recover helium to justify building a pump that does not have air contamination. This does not apply to liquid systems, because liquids are easier to seal. We have considered building our own pump, and it can be done, but after going over design specs it is just too expensive for us to do.

[Guga]

See my reply on Arena Blimp Pilots

[DonHelium]

Hi Guys !
I am living in Hungary, and I am making aerial photos from a let's say blimp.
BUT what is more important I made myself a compressor to refill the tank.
It's a small 3 stage compressor ( from the air starter of a military vehicle ), powered by a 0.75 KW electric motor. It is working fine, the top compression is about 3000 Psi ( with helium gas ).
My helium loss is about 20% at all. ( blimp loose 3%/day, compressor loose aprox. 15 % )

About the compressor: oil free 5 stage would be the best for this kind of application with 4500 Psi final pressure - but such device cost about 6000 USD.

So mine is a 3 stage, splash oil lubricated, slow ( 1.5Hr to deflate 3 m3 ), but it was relatively cheap. I am planning to build a better one - but for this I will have to sell this one. (~ 700 USD )

[Iepurila]

***

[DonHelium]

Good Idea, but it is working for only extremely big blimp, maybe the Hindenburg :)).
My compressor weight 40 kg, so that means a minimum of 50 m3 blimp. ( sorry for the european units ).

But following your idea is to put the compressor in a hermetically closed box, which is connected to the blimp's deflation hose.

[commandermike]

Thanks to everyone for your inputs... I think Galaxy has the best suggestion. To simply extract or vaccuum the lower 1/3 of the gas after giving the bag time to settle. After use, I hang my blimp bag vertically in a hanger inside of a nylon bag to keep it clean and let the contaminants settle to the bottom. Since I fly my blimp every month or two, I can easily suck out some of the gas from the bottom of the envelope before taking the bag down for it's next flight.

Thanks!
Mike

[DonHelium]

The main reason I have to pump off my balloon is that I have to transport it.
You can compare the price of a trailer with the price of the compressor.

The air contamination is depending on how much time the blimp is staying inflated. ( In my case max 3 hour ).

[Iepurila]

***

[Abuelo]

I live in the Philippines and we are about to start flying RC blimps in different cities around the country. Here helium is about $100 per k cylinder and only available in a few key cities.

Has anyone ever tried to re-compress helium from a blimp back into a cylinder, instead of venting it out and refilling with new gas? As we plan to travel between islands, it will not be cost effective to try and ship an inflated envelope, nor can we afford to vent gas and refill, everytime we change venues?

I am thinking using an air compresor (normally used to fill scuba tanks) to re-compress the helium gas each time we pack up... but would appreciate some inputs before we do.

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Is anyone out there trying to make his own blimp ?
Please let me know I would like to join that forum or project

thanks