Homemade Booster

[johnmaneely]

I'm in engineering and have all the gear to hand so thought I'd look into building a homemade booster. I know it can be a bit of a risky affair, but with the price of a Haskel its got to be worth a bit of research to see if its possible. I've seen a few drawings for hand operated boosters mainly for rebreather use, which would do me just fine. Just wondered if anyones had a bash(or bang)and come up with a useable item.

[bang-on]

<font color='#0000FF'>john,
i built one based on the air speed press book:
improvised and low cost hp gas boosters.
if you want i will send it to you if you remember where it lives.
the unit i built i used for a week and it worked fine but i was nervous using it and found it most efficient when driven by a compressor.
if you want this for trimix i found a better system,but if its o2 or high nitrox mixes your stuck with a pump unless you buy a bloody expensive compressor.
cheers
barrie

[Rob Evans]

Barrie, how cool is that?  Can it be driven by, say, a full 15l of air to turn the pump or is the compressor used to blow O2? Or is the 'other system' a better bet?
Most important, was it
A Complicated
B Bulk dollar

Want to use it to eke out the last couple of bar out of me garage He J

EDIT: John, if it's doable and cheap - put me down for one when you get round to it!  Your new best mate, Rob

[Alan57]

John
I too found the Haskel solution too expensive. However I recently took receipt of a Jetsam nanobooster from Canada. This ideal for pumping Inspiration 3l bottles with any gas. If you are an engineering type you can by the basic pump. I'm not so bought complete including guages and case for about £1250 . Exchange rates are now better = cheaper. I've copied his standard enquiry email below including technical stuff you'll probably understand.
Quote:
Standard info below.
The basic dimensions of the gas driven booster are 110mm X 110mm X 300mm.  The prototype weighs 3.2 Kg. without whips.

The first 50 are sold, but don't worry. I'll make more.

The pumping rate is a bit complicated with a pneumatic booster. The ratio between the drive piston and the output piston is 23:1. In theory a 10 bar drive gas will yield a 230 bar output. In fact the seal friction and the gas compressibility reduces the output to around 210-220 bar. The effective boost  ratio between the supply tank and the output tank can be as much as 5:1 ( 3:1 with helium ). So you could pressurize a tank to 200 bar from a supply tank at 40 bar. In practice you would use far too much drive gas to make it practical.  From what I have seen a 3:1 ratio is more realistic. When the supply tank pressure drops below 75 bar the drive gas consumption becomes excessive if you are using a scuba tank to drive the booster. Other variables are the relative size of the supply and fill tanks.

The drive piston displaces .29 liters per stroke. The output piston displaces .0126 liters. So a 12 liter scuba tank should provide almost 800 strokes at maximum outlet pressure. Inlet and outlet ports are 1/4 female npt.

As an example:

To fill a 2 liter tank which was at 170 bar to a final pressure of 210 bar from a 12 liter supply tank that had 110 bar of air took three minutes and 52 strokes of the booster. To fill a 2 liter tank from 100 bar to 210 bar from a 12 liter tank that had 100 bar took 10 minutes and 165 strokes.

If you want fill whips or other options the prices are below. If you already have whips you will just need to adapt to the booster ports.


Booster........................$1250.00 US
2 DIN 200 Bar bleeders..... 190.00
Line valve...........................45.00
2-60&quot; (1.5m).................... .166.00 (Swagelock SS/Teflon hoses)
Fittings...............................75.00
Gage..................................50.00 (2.5&quot; 0-5000psi &amp; 0-350 kpa)
Pelican 1500 case.......... ..125.00
Shipping...........................150.00

I'm not set up for credit cards or Pay Pal. Money order, bank draft, or wire transfer. Whatever is easier.
End quote.
Hope this helps. By the way he's the man who makes the KISS
regards Alan

[johnmaneely]

Thanks for the offer Barrie, I have a copy of the book on its way to me already. I'll read it through and then make my mind up about the safety side of things. What made you nervous? Were things heating up, was it struggling? Or did you just think, hang on a minute this a crap and highly risky idea.

I have also seen the Nanobooster, which seems like a good bit of kit. I'm just a bit tight and don't want to fork out that much cash, but if things don't work out I may look into it further.

Rob, gotta fully get the picture on costs and the amount of work involved. I'll make just the one to start with and fiddle around with it to improve things, if things work out well I'll probably knock out a few.

John

[bang-on]

Originally Posted by [b

Quote[/b] (johnmaneely @ Feb. 04 2004,18:49)]What made you nervous? Were things heating up, was it struggling? Or did you just think, hang on a minute this a crap and highly risky idea.

<font color='#0000FF'>the pump would cycle when using the compressor to feed the ram and would transfere about 4bar per stoke.
each stroke took roughly 15 seconds but as the pressure in the filling cylinder became higher the &nbsp;stroke then took 20 sec untill it would not pump further.
i think if your in a shed with a stack of o2 under 200 bar pressure and homemade pump being driven by a compressor!!
you would need to be a double hard bastard not to be a bit nervous.
cheers
barrie

nb if you decide to build one a bloke in leeds owes me a 20ton
air fed bottle jack.

[bang-on]

Originally Posted by [b

Quote[/b] (Rob Evans @ Feb. 04 2004,02:19)]Most important, was it
A Complicated
B Bulk dollar

Want to use it to eke out the last couple of bar out of me garage He J

EDIT: John, if it's doable and cheap - put me down for one when you get round to it!  Your new best mate, Rob

<font color='#0000FF'>rob,
a complicated
not really the book gives most options for ram size and type as well as diferent ways to drive it.
it helps if you can build for cc because of the smaller cylinder sizes.
b bulk dollar
cost about £140 for allthe bits.

are you partial pressure filling your 3's from the he j and getting left with 60 or 70 bar unusable?

can you get your hands on a couple of empty j's?

do you have access to a half decent compressor.

cheers
barrie

[Rob Evans]

Originally Posted by [b

Quote[/b] ]are you partial pressure filling your 3's from the he j and getting left with 60 or 70 bar unusable?

That's about right. TBH it's not that much of an agg getting a fill, just involves a bit of a trog to Canvey Island &amp; back with a dirty great tin in the back of the car, so am looking for a different option. Well, browsing really.

Originally Posted by [b

Quote[/b] ]can you get your hands on a couple of empty j's?

Yup

Originally Posted by [b

Quote[/b] ]do you have access to a half decent compressor

No &nbsp; I suspect this is the sticking point.

[johnmaneely]

Barrie, I assumed the booster would cycle faster then what you have mentioned, put less gas in with each stroke as it were. I take it cylinder size, ratio of in to out could be altered in the design or some form of stroke adjustment during operation. I do not yet have the full understanding of booster operation, which may appear obvious. I also have the same problem with J's of He with a lack of pressure in for decanted. I do have access to the mentioned items, you gonna let the secret out of the bag?
Thanks
John

[bang-on]

<font color='#0000FF'>john,
given a few empty j's and a good compressor i connect the full j of he to two more j's (emptys but o2 clean with the nonreturn valves removed) and allow them to equalise fairly slowly.
i then check the pressure across the 3 cylinders,this figure then dictates how much o2 to add for the required mix.
after adding the o2 slowly i then connect the whip to a personnell filter and on to the compressor outlet this then brings up the pressure to my desired amount. &nbsp;
now i have about 141 lts of a mix this can then be decanted back into diving cylinders when pressure drops in the three cylinders i can then coonect the whip to the inlet of the compressor and top of the cylinders being filled.
with the use of a needle valve on the end of the whip i can control the flow to the compressor and totally empty the j's.
notes;
uses all avaible helium.
is good if your doing a lot of deeper stuff.
diving cylinders being filled do not need to be o2 clean as only a small % of o2 is normally present in trimix.
you could have a slight drop in he in mix after topping of through a compressor so a he analyser is a good idea.
i label j cylinder before returning empty to supplier asking for &nbsp;it to be cleaned.
this works for me and i do not suggest it is safe or recommended &nbsp;practice.
cheers
barrie