Teach me about boosters

[broncobowsher]

Picked up a rebreather and dealing with fills. The local shop doesn't pump O2. The one that does is not close. I'm never lucky enough to be there when they are filling. The end result, 6 hours of driving to get an O2 fill. That's if the traffic is good. Time to look into spending more money and get a small booster.

I know of boosters, never used one. There is a nice shop compressor in my garage, 2-stage, 5HP, 13 CFM. It runs clean. Planning on using that for drive gas. Pumping O2 now. Expecting to pump He soon as well. This is just going to be personal use. So something small.

Not looking for someone selling one. Looking for info on what to look for. Haskel and Hydraulics International are to names I know of. What else should I know about? Any booster 101 classes?

 

[tbone1004]

get a baby booster, which one is up to you but doesn't really matter which one you get, they're all equally inefficient for what they are. Used is fine, but if it needs rebuild, budget about $400 for the parts from Haskel. They do have service videos on youtube, they're stupid easy to rebuild.

I would recommend spending a bit of money filtering the shop compressor. Clean though you may think, your booster will appreciate cleaning and it needs to be filtered to 5um or so per the manufacturer.
I got one of these for my AG30 which spits out Grade D air which is more than clean enough for boosters. Only difference between it and scuba "grade e" air is the conversion of co to co2 which the booster doesn't care about. Costs about $400 and is probably more than overkill, but if it saves at least one rebuild of my AG30 over the life that I have it, it will have paid for itself just in the parts
350 SERIES Modular Clean Air Package 1/4, 3/8, 1/2

After that, there isn't a lot to it. You'll want to keep it cycling less than 1 cycle per second, open valves slowly, etc etc. The manuals out there are pretty good.

 

[broncobowsher]

I was planning on a dryer and I have had good success using motorgaurd filter on the shop air. Painters love them, my plasma torch has always been happy with one in place for the past 15 years. I've always heard of them as a great compressed air filter. My intention is to just use the compressor at home as drive gas. Any breathing air will still come from the dive shop (the local one that doesn't pump O2). I still have plenty of big tanks around.

I wasn't sure if there are any to avoid? Or any that have an outstanding reputation, or crap reputation? I understand that they are not efficient, nor do I really care. I have been watching used ones pop up, but not knowing much about them I tend to back pedal a little not knowing what I am looking for, or what I should be looking for. When they sell right away I guess that was a good one, but I wouldn't know if something that isn't worth rebuilding.

 

[tbone1004]

@broncobowsher depends on the degree of filtration from the motorguard, but if you have one of those they will certainly help, especially with a drier. I got the clean air package to put in my pelican case so I can use any air source, but if you have this thing permanently mounted then a drier and something like the motorguard should be fine, just make sure the filtration level is low enough to at least meet the factory recommendation for the booster you purchase.

that's a great deal. Spend about $800 or so on the parts I think since it is 2-stage and O2 clean it and you have the gold standard of O2 boosters on the market for less than half price *New is $7k*. A new baby booster is $2250, so an extra grand and you get 30:1 instead of 25:1 *really nice for dil bottles since the baby booster dies around 3300psi vs. 4500psi for the 15/30* and a lot more capacity since it's a beast.
Haskel Booster

 

[flymolo]

I imagine this book could also be helpful:
Vance Harlow's OXYGEN HACKER'S COMPANION From AIrspeed Press

 

[Gareth J]

Just remember to compress the oxygen SLOWLY.
You can generate a lot of heat compressing oxygen, heat and oxygen are not a good combination!
Especially combined with fuel!

Basically it means running the Booster pump slowly, which means controlling the drive pressure.

 

[tbone1004]

Just remember to compress the oxygen SLOWLY.
You can generate a lot of heat compressing oxygen, heat and oxygen are not a good combination!
Especially combined with fuel!

Basically it means running the Booster pump slowly, which means controlling the drive pressure.

also of note, O2 really shouldn't be compressed more than 4:1 per stage. If you're going from real low supply bottle pressure, you'll want to go to an intermediate bottle to prevent that heat buildup. so at 100 psi on the supply bottle, you'll want to boost into a bottle up to 400psi, then take that and boost to 1600psi, then you can take that up to whatever final pressure you want. Most people don't do that, but it's what you're supposed to do. If 3000psi is your final o2 pressure, once your supply bottle gets below 800 you should go to an intermediate bottle.

 

[broncobowsher]

@broncobowsher depends on the degree of filtration from the motorguard, but if you have one of those they will certainly help, especially with a drier. I got the clean air package to put in my pelican case so I can use any air source, but if you have this thing permanently mounted then a drier and something like the motorguard should be fine, just make sure the filtration level is low enough to at least meet the factory recommendation for the booster you purchase.

that's a great deal. Spend about $800 or so on the parts I think since it is 2-stage and O2 clean it and you have the gold standard of O2 boosters on the market for less than half price *New is $7k*. A new baby booster is $2250, so an extra grand and you get 30:1 instead of 25:1 *really nice for dil bottles since the baby booster dies around 3300psi vs. 4500psi for the 15/30* and a lot more capacity since it's a beast.
Haskel Booster

I looked at that used one. The assortment of used red shop hose and what looked like a garden valve was not that appealing to me. Looking at that one, then looking at a brand new baby booster at what is the same price, the baby looks like a better deal to me. Add in the $800 rebuild. Not knowing much about them to start with, starting with a good new unit looks better.

I'm not looking to fill to 4500, just 200~232bar. Is there something that the 2-stage offers that would be a huge benefit? I'm not looking to pump up 120s, mostly just 3L rebreather bottles. Maybe top off a bail out a time or two a year.

I get it, pump slow. Open valves slow. Don't be in any hurry. I've only had one accidental Oxygen fire, few more intentional. I've owned oxy-fuel torch set for a very long time.

Everything seems to be centered around a Haskel, anything else I should consider? At the moment a Haskel baby booster is probably the direction I am leaning. For roughly $2k new I wouldn't really have to worry about used issues. And I do realize there will be way too much money tied up in whips and tank adaptors on top of it as well.

 

[tbone1004]

the 15/30 will allow you to scavenge out of bottles better and removes the need for intermediate boosting when supply pressures get low, it will allow you to boost to higher pressure than 232bar which you may want on dil/inflation, but that's about it

another option
Haskel AG30 Oxygen Clean Booster For Sale SUPER CLEAN $2900

 

[DA Aquamaster]

Some general thoughts....

1) Compressed air gets hot and hot air will hold more moisture than cool air. Consequently, when that compressed air cools, the water in it will condense into liquid form. What happens then is that moist air is compressed and heated by the compressor and if fed directly to the Haskel, it will expand and cool in the drive section of the Haskel and leave the condensation in the drive section and cooling jacket sections of the Haskel.

In the Ag-30, all of the O-rings in the drive section, cooling jacket and cycling valve sections are standard sizes that can be obtained from McMaster Carr for a lot less than Haskel sells them. Consequently, there isn't any reason not to rebuild the drive section annually.

2) Oil from the compressor just adds to the mess in the drive section. An oil-less compressor helps keep the drive section of a Haskel a little cleaner, but it's not an oil lubed compressor is not a deal breaker, you just want to ensure you have really good moisture separation and filtration.

3) Consistent with what is described above, a moisture separator is important, but it won't work without some type of condenser. I live in NC with both high temperatures and high humidity in the summer, and high humidity in the winter so moisture is a big deal. I run my drive gas through 50' of tubing submerged in a 5 gallon bucket of water. I'll chuck a few large freeze packs in the bucket 15 minutes or so before I start boosting to chill the water. The compressed air is then chilled as it goes through the tubing in the cold water and then is passed through a moisture separator. That ensures that most of the moisture is in liquid form when it reaches the separator.

4) It then goes through a filter, and the passes through a desiccant to remove most of the remaining moisture. The humidity of the gas reaching the haskel is consequently low enough that it won't condense in the drive section when the air expands and the temperature drops.

5) I own my own K bottles and I own two of them. This lets me use one down to about 750 psi while boosting directly into the destination CCR O2 bottle at 3000 psi. Then, I switch to the second O2 K bottle and run it down to about 750 psi, directly filling my CCR bottles. At that point I then boost O2 from one of the 750 psi K bottles into the other 750 psi K bottle down to about 200 psi. This leaves the "high" O2 K bottle at around 1250 psi, where I can then continue boosting from it down to about 750 psi, while I exchange the 200 psi bottle for a full bottle. The end result is that I using an intermediate pressure bottle without requiring me to have an AL80 or similar sitting around for that purpose.

6) I use a 5 CFM compressor for my drive gas. It's sufficient to run an AG-30 at about 1 cycle every 6 seconds. That low rate also keeps the O2 cool and the high pressure section and fill lines on the Haskel never get more than just mildly warm to the touch. I know shops that boost O2 so fast that you'll burn yourself if you touch the lines. That always makes me very nervous.

A 13 CFM compressors is fine, just don't go crazy with the cycles per minute when boosting and take care to keep the temperatures cool.