Booster recommendations

[AndyNZ]

Some context first - trimix isn't cheap, and it's difficult to get hold of for us. It's rare that we will ever be anywhere that we can just top up trimix.

After a fairly normal dive in the 50m+ range, we'll have two twinsets of trimix each with around 100bar (1500 psi) that isn't enough to do a second dive (with reasonable gas reserves), and with no continuous blending stations available means we have to face the prospect of opening the valves and letting $100 worth of gas just go...

I'm open to suggestions for ways to save or reuse that gas!

First thought was to use a booster pump to transfill from one twinset to the other - any suggestions on the most appropriate booster?

Thoughts on requirements:

1. Doesn't have to be O2 clean
2. Can be either pneumatically or electrically driven
3. Time taken to transfill is not too much of an issue
4. Cost should be as low as possible

Any thoughts or suggestions?

 

[dannobee]

Have you explored just starting with a richer He mix, then topping off with air or nitrox?

Any other method will set you back at least a couple thousand dollars, likely two or three times that much when it's all said and done.

I save mixes by running them through my compressor and adjusting the mix as needed with a trimix stick (continuous blending).

A "good" booster will likely set you back as much as a small compressor, and you'll still need a shop compressor to drive it.

 

[AndyNZ]

Any other method will set you back at least a couple thousand dollars, likely two or three times that much when it's all said and done.

A couple of thousand we could maybe live with - filling a twinset costs around $240+ here.... it doesn't take much to pay back the investment if we're dumping the gas we don't use!

I save mixes by running them through my compressor and adjusting the mix as needed with a trimix stick (continuous blending).

We're currently tranfilling He into empty tanks, and topping up with continuous blended 32% nitrox to give us the mixes we are after. It wouldn't take much to change the continuous blend system to make it a full trimix blending station - which means that we can just top up the tanks whenever. But realistically we're only diving trimix now and again - so it means having a dedicated set of twins sitting around half full for a while until we top them up for the next dive.

Just trying to work out the best way of doing things - it maybe that the cheapest way is to have a dedicated set of mix tanks and change the continuous blend system for mix. Thanks for the input.

 

[boydski]

Hi Andy,

The best booster for recovering trimix/helium from one set of tanks to another is the MasterLine Booster. They are electric, simply push the button and they will suck one set down to 300 psi (20 bar) while boosting the other set to almost 3000 psi (200 bar). The downside is that they are very expensive. The Oxygen Clean version is $6000.

Another alternative is the Hydraulics International booster. It is air driven (uses a lot of boost air), but costs about half of what the MasterLine costs.

I have no idea what the shipping or availability of these products in Auckland would be, but I'm amazed at all the gas we save by using our MasterLine.

 

[wwunder]

what about building an "omni booster"? essentially a second stage rigged to freeflow with a hookup to the compressor inlet. Then just pump the mix from one set of half empty doubles to the other and then just fill one empty set. If you can't find much about it here, check the deco stop.

 

[Camerone]

I'm a big fan of the Jetsam Baby Booster (Kiss Rebreathers and Boosters) I found a used one, with a full set of whips, gauges, hand-tight nipples for inert and O2, DIN fittings, and Parker QDs for $1000. They come up with some frequency, and brand new, they're only around $1500 USD. Add $250 for an oilless shop compressor, and a little for whips, and you're good to go for not a lot of money.

They are _not_ the most efficient boosters out there. It's single stage and slow, but it's also insanely portable, field strippable, and brain-dead simple to repair when it needs it...literally a 15 minute rebuild if it ever does need it.

I use it to scavenge O2 and He when I refill from the welding supplier. He isn't cheap here, either!

 

[waikatoman]

Andy, any booster that will shift the volumes required for OC trimix at low supply pressure is going to be relatively big and costly. I'm sure you already do this as you specifically mention wanting to use a booster, but if its hypoxic or normoxic trimix you're wanting to shift, feeding the gas into the intake of your compressor and pumping it into the desired sylinder has got to be the easiest solution.

I have a baby Bauer (2.5cfm) with which I routinely scavenge He from one G to another, and it works plenty quick enough. I have noticed you have to watch the 2nd and 3rd stage head temps when pumping pure He though.

You're welcome to drop around and take a look at the plumbing next time you're in Tuts if you wish (not that it's particularly elegant).

Greg v

Edit: I just saw the dumping gas comment at the end of your post. Feel free to drop around after diving at the Knights if you have leftovers in your twins - I'm happy to provide a cup of tea and a biscuit while you 'dump' any mix into my compressor intake. Call me cheap, but dumping mix...you're making me cry here!

 

[AndyNZ]

Edit: I just saw the dumping gas comment at the end of your post. Feel free to drop around after diving at the Knights if you have leftovers in your twins - I'm happy to provide a cup of tea and a biscuit while you 'dump' any mix into my compressor intake. Call me cheap, but dumping mix...you're making me cry here!

At the moment, we're not dumping..... but are running out of twinsets, as four out of our eight sets are all half full of trimix whilst we try and work out what to do to save it!

Will definitely have a look next time I'm up - will be sometime in October.