I finally decided that after taking too many trips and spending long nights inside a dive shop waiting for O2 and Diluent fills that it was in my best interest to purchase a mini booster for filling my rebreather bottles especially since I have easy access to T bottles of O2 and Helium. Jesus..You’ve only had a rebreather for a year and only just broken 150 hours of diving on your unit and you already want to buy booster?! Luckily as I tell many people, Jesus is my go-to dive buddy when diving alone; He’s not just the name of some Mexican guy. With Jesus on my side I decided to venture into the land of boosters. I’m still waiting for the SCUBA police to knock on my door and tell me what I am doing it just plain wrong.
Choosing a Mini Booster
There are several different brands of mini or “baby” boosters available today. These mini boosters are marketed specifically towards rebreather divers and they are small enough to take on a plane or a road trip with you. In fact, if you think your rebreather scares TSA, just wait until you show up with one of these pipe bomb looking devices! I have no doubt they will love you. All kidding aside, these mini boosters are tiny and should travel well. I’m just slightly jaded by my last TSA and Mexican customs experience.
Although you can fill larger cylinders with them it would be largely impractical and take forever and use a ton of drive gas. They are really only designed for filling 2L (13cu) and 3L (23cu) bottles. I could maybe see myself topping off some AL40s/AL80s in a pinch but you would be kidding yourself if you think you’re going to be filling doubles with one of these. If you have a need to fill larger cylinders or doubles let me stop you right now. Please do yourself a favor and buy a larger booster from the start.
The two most popular mini boosters seem to be made by Haskel and Hydraulics International, Inc (HII). There is another model made by Stansted Fluid Power Limited that is also popular with UK divers. These were the 3 models that I initially looked at but I decided on the Haskel Mini Booster (MSB-9000) primarily out of price consideration, availability and ease of parts and service in the United States.
The Haskel Mini Sport Booster (MSB-9000) was on sale at DiveGearExpress for $1999.00 but it seems to be normally priced at $2300-$2600 depending on where you purchase it. I could have also went for a used booster for around $1000-$1500 but I didn’t want to deal with the unknown service history of something that could have easily been heavily abused and had questionable O2 clean status from the last century from Fred’s backyard garage and oil compressors. The Haskel Mini Sport Booster comes O2 clean from the factory so I figured I would take the guessing part out of the equation and buy something I know didn’t have a billions of cycles of abuse on it.
Drive Gas Components
These boosters are designed to be run off an LP port of a typical SCUBA first stage regulator and tank or larger high capacity/volume shop compressor at 150psi for the drive gas to “power” the booster. I’ve been advised that ultimately it would be best to run from a shop compressor in the future since depending on the pressure of the source gas you’re trying to boost you may use a “shit ton” (technical term) of drive gas to boost to your target pressure.
Please note: If you’re going that route make sure you get some sort of filter and water separator for your shop compressor before connecting to the drive gas inlet on your booster. It will make your booster last much longer as the air coming from a shop compressor tends to be very dirty and have lots of moisture, the exact opposite of most Grade E from a scuba tank.
For now to drive the booster I found an old Aqualung Calypso first stage I had not used in a while adjusted the IP to around 145psi, added an SPG, over pressure valve (OPV) and a LP inflator hose. I’ve been told I would get better performance if I run booster from around 150-155psi but I wanted to build in a little safety margin. The booster itself has an OPV that is set to go off at approximately 155-160psi and the OPV on my first stage should go off around 155psi. I’ll probably swap regulators to something balanced at some point since the Calypso first stage is unbalanced and the intermediate pressure drops to around 135psi when my drive gas supply runs low. Since it was free and I already had it, I figured I would use it.
For drive gas, the booster inlet is ½” NPT so I used a ½” NPTm to 1/4″ NPTf reducer bushing so I could plumb everything using ¼” NPT. I hooked up an Intermediate Pressure gauge, ball valve and standard LP inflator adapter so the booster could be driven from any scuba regulator with a low pressure inflator. Pretty neat
Whip Setup and Components
There are many commercial whip kits available for your booster. Most of them cost $700-$900 or more. I decided to go the DIY route and build my own whips which cost considerably less money and are much more versatile. The only thing I am lacking right now is a digital SPG which I will be adding in the future. The majority of the components used were purchased from McMaster-Carr. Everything is plumbed together using quick disconnect couplings. All threads and adapters are ¼” NPT and most fittings are rated for 5200psi. The high-pressure braised hose is really the only thing rated lower (3000psi) but the burst pressure is much higher. As a result I have no issues running 3500psi through this thing.
All fittings, adapters and quick disconnects were O2 cleaned using hot water and a solution of Simple Green and given a thorough rinse and dried. If you are not a DIY type of person, save yourself the time and just buy the pre-made whip kits. I considered this a learning experience and I like to fiddle with things. Verify EVERYTHING is rated for high pressure before assembling.
The major difference between my whips and the commercial ones is that I added check valves in each end as an extra precaution and added a needle valve to control flow. You can leave these things out but honestly if you’re doing any sort of blending then you’ll be very glad to have them. These whips can be disconnected from the booster and used independently as a transfill whip for partial pressure blending. All of my supply tanks are equipped with a male quick disconnect fittings.
Here is an approximate list of parts I ordered along with prices.
|1||79215A663||Regulator Fitting, Inlet Nipple, CGA #540, 2-1/16″ Long||3.17||$ 3.17|
|2||79215A665||Regulator Fitting, Inlet Nipple, CGA #580, 3″ Long||3.34||$ 6.68|
|1||6537K11||High-Flow Hose Coupling, Brass Plug, 1/4″ NPTF Female, 1/4″ Coupling Size||4.42||$ 4.42|
|2||4468K132||High-Pressure Braided Chemical Hose, 1/4 NPT Male Brass Fittings, 3000 PSI, 48″ Long||26.68||$ 53.36|
|1||8549T13||High-Pressure Brass Check Valve, 1/4 NPT Female x 1/4 NPT Male, Buna-N Seal||21.15||$ 21.15|
|1||8549T15||High-Pressure Brass Check Valve, 1/4 NPT Male x 1/4 NPT Female, Buna-N Seal||21.15||$ 21.15|
|1||9171K27||Precision High-Pressure Brass Thread Pipe Fitting, 1/4 Pipe Size, Female Tee||18.44||$ 18.44|
|3||6537K91||High-Flow Hose Coupling, Brass Plug, 1/4″ NPTF Male, 1/4″ Coupling Size||3.63||$ 10.89|
|1||9171K73||Precision High-Pressure Brass Thread Pipe Fitting, 1/4 x 1/4 Pipe Size, Hex Coupling||7.95||$ 7.95|
|1||44945K12||Military Grade Pipe Thread Sealant Tape, Premium, 14 Yard Length x 1/2″ Width, Green||6.12||$ 6.12|
|2||6537K63||High-Flow Hose Coupling, Brass Sleeve-Lock Socket, 1/4″ NPTF Male, 1/4″ Coupling Size||8.24||$ 16.48|
|2||6537K73||High-Flow Hose Coupling, Brass Sleeve-Lock Socket, 1/4″ NPTF Female, 1/4″ Coupling Size||8.41||$ 16.82|
|1||9171K32||Precision High-Pressure Brass Thread Pipe Fitting, 1/4 Pipe Size, Female x Female x Male Tee||18.82||$ 18.82|
|Other parts below…|
|2||SS-6-SAE-7-4||SS Pipe Fitting, Adapter, 9/16-18 Male SAE/MS Straight Thread x 1/4 in. Female NPT (Swagelok)||22.44||$44.88|
|2||DX-70144||ACCURATE CYLINDER PRESSURE CHECKER (DiveGearExpress)||36.50||$ 73.00|
|1||031 571||Oxygen Hand Tight Nut (Northeast Scuba Supply)||16.99||$ 16.99|
|1||031 007||Inert Gas Hand Tight Nut – Helium, Argon, Nitrogen (Northeast Scuba Supply)||19.99||$ 19.99|
|1||031 059||Needle Valve – O2 – Male To Male||39.99||$ 39.99|
Connecting Whips to Booster Inlet and Outlet Ports
In order to connect your whips to the booster inlet and outlet ports you will need adapters. The inlet and outlet ports on the Haskel (and I believe HII booster too) are 9/16” SAE (AKA 3/8″ SAE) female threads. Swagelok and AddHelium both sell the correct adapters to convert to ¼” NPTF. From here I connected mine to quick-disconnect couplings which are on my whips to make the booster easy to break down for travel.
Diagram and Overview
Before I purchased anything I made a quick mock-up of all the parts I needed so that I had a better understanding of how everything would fit together.
Other Whip Components
Supply gas tanks are connected to male quick-disconnect couplings to easily plumb gas from different sources. The supply end of the whip also has a one-way check valve to prevent feeding back into source bottles in case of dissimilar pressures and a pressure gauge for reading supply pressure.
The other end of the filling whip has a needle valve to regulate flow and another pressure gauge. I am going to replace this with a digital SPG in future for more accurate blending but for now it works fine.
Holy crap this thing actually works and it’s quiet! Since I’m not running it from a noisy shop compressor right now it’s very quiet. It barely managed to wake my cat sleeping about 20ft away. For my first test I was able to boost a completely empty 3L diluent bottle to around 3300psi from a source supply pressure of approximately 1200psi. After slowly equalizing the both the supply and destination tanks using the whips on the booster I started the boosting process by connecting the first stage to a AL80 and slowly engaging the ball valve on the drive gas until it started to cycle and “boost.”
I didn’t take any initial timings or track how much drive gas the booster used since I didn’t check how much gas was left in the AL80. I’m pretty sure though I completely drained whatever was left in there and then proceeded to top off my diluent bottle another half full HP120 I had lying around.
I’ll have to do more testing later but so far it seems to be working great. I haven’t tried boosting anything larger than a 3L (23cu) bottle yet.
Helpful Links and Thanks
I definitely spent a couple months scouring rebreatherworld.com and CCRexplorers.com forums before purchasing anything to see what others were using and doing. I don’t pretend to be an expert on anything and I would greatly appreciate any help or additional information if something I said here is wrong or outright dangerous.
There is undeniably lots of great information on these forums if you can weed through the constant bullshit and macho bravado. Underneath the battle of which rebreather is better, which diluent or heliair mix is less likely to kill you or which size bolt snap is better, you will find some quality information if you can read between the lines.
I will just say that lots of internet “experts” like to talk a big game but few actually get off their ass and dive. I like to call them “internet divers.” They have over 10,000+ INTERNET DIVES (forum posts) but maybe only about 50-100 actual REAL dives in challenging conditions outside a quarry or Carribean destination. Don’t be an internet diver, go out and talk to people actually doing this stuff and form your own opinions.
For those that don’t already own it, Vance Harlow’s Oxygen Hacker’s Companion is also an invaluable resource for anyone looking to get into blending or work with oxygen. He demystifies many of the misconceptions and “trade secret” knowledge regarding oxygen cleaning and handling oxygen in the scuba industry.
With that also being said, reading is not always a subsitute for formal training. I’ve taken PSI’s cylinder inspection and oxygen cleaning courses before. Alex at East Coast Divers also offers a pretty comprehensive oxygen cleaning and cylinder inspection course through SDI/TDI that I found very helpful. He is a wealth of knowledge.
Richie Burr’s article on RebreatherWorld.com was the most straight forward and helpful article I found. You’ll notice that some of my whip designs are very similar to his setup. I don’t know him but I thank him for his post.
My friends Sang and Matt were also very helpful in answering some of my stupid questions since both of them also own boosters. A bunch of other people whom I’ve never met except on Facebook also helped me source random odds and ends that I would need and humored me with some very basic questions.
I hope this little guide helps anyone looking into getting a booster. Please let me know if any of this information or blatantly wrong or dangerous or if you have any suggestions.