How to refill your own CO2 liferaft cylinder

**robind** · 09-08-05, 15:17

Divers fill their own cylinders! so is it practical/possible to fill the cylinders of a liferaft? I understand that an "additive" is included with the fill "to assist the gas to operate smoothly and effectively" is this so? and what is the additive?

Would it be better simply to visit Air Products and get it filled? or is it economical to purchase/hire a large cylinder and do it myself?( given the legislation regarding transportable gasses etc). I am talking about a commercial situation not just an individual with 1 liferaft?

Rob

**andy_wilson** · 09-08-05, 15:35

For commercial use there is a requirement to have the raft serviced and certificated each year by a competent body.
Not a DIY job then.

**Talbot** · 09-08-05, 15:40

filling the gas cylinder is only half the story. The folding of the raft is a recise science to enable to to unfold properly and hopefully the correct way up.

**savageseadog** · 09-08-05, 16:26

The mix is about 10% Nitrogen it helps to propel all the CO2 out of the bottle

**mainmarine** · 09-08-05, 18:09

This link show a liferaft being serviced, it is quite easy to refold it if you video it being unfolded.
http://www.sailingboatefaki.gr/liferaft.htm

Malc
Mainmarine

**jerryat** · 09-08-05, 20:49

Yep, that's exactly what friends of mine do. I have also unpacked, inflated and re-packed my own Avon. With a good photo record taken as you open it up, re-packing is really simple.

Agree that refilling the cylinder is not a starter for the amateur.

Cheers Jerry

**William_H** · 10-08-05, 02:31

The problems are that the cylinder will need to be hydrostatically tested periodically. If you are an amateur you can ignore that but as a commercial operation you can't. The next problem is that if you buy/hire a large cylinder of CO2 then in fact the pressure required for your small liferaft bottle is so high that after decanting from the main bottle you don't have as much pressure as you need to get the liferaft bottle full.
You start with a large bottle 2000psi. You decant to a small bottle of only 5% of the capacity of the big bottle. This brings the big bottle down to 1900 psi and of course your small liferaft bottle to 1900 psi. If you meed more you need another full supply bottle to get it closer to 2000psi.
The way the commercial people solve this problem (as do scuba dive tank fillers) is to use a half full supply bottle to fill the receiving bottle to half full. Another bottle perhaps 3/4 full to bring the receiving bottle up a bit more and use a full supplying bottle to provide the last little bit to get the pressure up. if you follow my waffle. the only alternative is to have a comopressor. When we are talking 2000 to 3500 psi we need a multistage compressor very sophisticated.
So of 3 liferaft servicing companies I have done quality audits on here in Fremantle, they all send the cylinders to a commercial gas bottle servicing company. So basically forget it. as much as I advocate DIY. regards olewill

**jerryat** · 10-08-05, 07:49

Hi Will,

That's just what I said!! NOT a starter for the amateur!! [img]/forums/images/graemlins/laugh.gif[/img] [img]/forums/images/graemlins/laugh.gif[/img]

Cheers Jerry