Diver Dave's Haskel-Pump Page 

One name comes to mind when discussing air-drive booster pumps, and that's "Haskel". Known for aerospace quality, with corresponding Aerospace prices, these are the best that money can buy. These pumps have been made to boost nitrogen, air, oxygen, and many other gasses, for aviation, industrial, and life-support operations. In addition, other versions actually pump liquid, as hydraulic system pressure boosters. There are many different models, some with 2 cylinders, others with one, some driven off of the actual gas that's being pumped, others using an air-supply to pump a second gas, etc. Essentially, the system uses a piston with a large end and a small end. The large end is pressed upon by a low-pressure gas, and that piston then pushes a smaller volume of gas to a higher exit pressure. The boost ratio is the difference between the surface area of the larger and smaller pistons. You would think that a higher ratio would be better, but remember that the quantity of drive-air is a function of ratio as well. If you only need to pump 3:1 boost, you'll use 3 cubic feet of air to drive 1 cubic foot of gas. With a 50:1 ratio, you can make higher pressure, but it will take 50 cubic feet of air to drive 1 cubic foot of gas. Remember that the ratio is between the BOOST gas supply, not the BOOSTED gas supply. Meaning that the exhaust pressure is the ratio between the AIR supply and the exit pressure needed, not the ratio between the donor gas supply and the required outlet pressure. When picking one, remember that these things eat up air like it's going out of style. You WILL need a compressor of your own to run one.

Now, on to the controversy regarding these: Many of the smaller pumps that are used by divers originated as nitrogen boosting pumps for aviation use in servicing the landing gear struts of large aircraft. These were NOT originally designed as oxygen compatible pumps, and Haskel will absolutely deny that they are safe to use with 02. Plus, we know of at least two incidents where these pumps suffered oxygen fires in use. Here's opinion on this subject: I believe that these pumps are safe to use with 02 IF and ONLY if you do the following:

 

1: The entire system MUST be 02 cleaned. I know that the pump I bought was "supposed" to have been cleaned, and when I opened it up, it was filthy with years of accumulation of oil. You can ONLY trust that it's been 02 clean if YOU clean it. The military used oil-pumped shop-air to drive these in aviation use and, as you'll read below, oily drive air will contaminate the entire system given enough time.

2: The drive-air MUST be 02 compatible. There is a very slight mixing of the drive gas and the driven gas in these. This means that if you use oil-lubricated shop-air to drive the pump, you'll end up with minute quantities of oil on the 02 side. This mixing is not enough to change the purity of the exiting gas, it's just a trace. However, a trace of oil is too much. I use an oil-free RIX compressor to pump my drive air cylinders (normal SCUBA bottles), and then I use that oil-free air to drive the pump. I believe that this is the reason that some people have had problems with their pumps.

3: You MUST introduce 02 slowly into the system, using a needle-valve. To have a fire, you need fuel (oil), oxygen, and heat. The heat of compression from opening up a supply cylinder into the pump is enough to cause a fire. You NEED to use a needle valve to SLOWLY pressurize ANY oxygen system.

These are just common sense items for ANY oxygen transfer system. There are 02 compatible oils, and if you decide to drive one of these pumps using an oil-lubricated compressor, pay attention to this. Draeger and the Russians use glycerin lubricated leather seals on their pumps, and you would think that these would be fuels for a fire., The fact is, though, that glycerin is inert and that the lubricated pumps run slowly enough so that there's no heat buildup IF you don't pressurize the system too quickly.

 

The bottom line is to BE CAREFUL when working with pure 02! Pay attention!

 

Ok, enough whining: Here are the pictures: 

 

Here are the two most common boosters that are used by divers. The top is the military surplus nitrogen booster, which is my own pump. The bottom is a double-acting booster which pumps "going both ways", so to speak. Both do the same job. The booster that you end up with is going to be more of factor of what you can find, not what you want. These baby's are expensive, so when you are beggin', you aren't going to be choosin'. Any of them will work fine, as long as you KEEP THEM CLEAN.

Here's my own system set up in the driveway for boosting 02 into a Mark-15 sphere. The green cylinder at top right is the 02 supply, the sphere is at the bottom left, and the yellow cylinder is oil-free air fed into the drive-air port through a standard SCUBA first stage and supply hose. 

Here is my modular system. The hoses are quick-disconnect ones, and the two hoses for supply and feed can connect to each other directly for use as a transfill hose when I don't need to boost. The drive-air regulator also has a quick-disconnect fitting for ease of break-down for transport. A selection of adapters rounds out the system.

Here are the adapters, which allow me to connect my yoke hoses to (Left to Right) Russian small diameter 02 fitting, DIN, LAR-V, Oxygen, Inert Gas, and Medical 02. Since I took this photo I've added the standard European oxygen fitting (for the Azimuth, RGU-FM, FGT-1D, and AKA-60) and the fitting for Draeger Dolphin. With these, I can connect anything to anything, without using tools to change fittings.  These adapters deserve their own Adapter Page, so go there and see them in detail!

 

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