Jun 08 07
It has been some time since any serious toy purchasing has been undertaken. This situation was rectified this week when Andy and I bought a second hand oxygen booster. This is a very useful bit of kit which takes supply gas and boosts it to anything up to about 250 bar. Using the booster we will now be able to fill our rebreather oxygen cylinders to the 200 bar mark and above. This gives us the capability to do longer duration dives. We don’t intend to do longer duration dives but we now have the capability, which is the point, isn’t it?
The booster uses a standard scuba cylinder to provide drive gas via a regulator and inflator whip. The oxygen is fed from a supply cylinder (in this case an 18 litre filled with O2) into the booster. The compression ratio of the booster is 20:1. The rebreather oxygen cylinders are both 3 litre capacity and only take a few minutes to top off to 200 bar even with the slow booster cycle rate of 1 stroke per second to avoid overheating the oxygen. Overheating oxygen is not a good idea. Andrew may want a new garage but this is not the best way to go about getting one.
The picture shows Marcus inspecting the new toy and feeling the cooling effect on the drive cylinder tap. After pumping the second cylinder with O2 the drive cylinder had cooled to the point of cutting off the supplying gas. The demand valve still worked okay but the cylinder tap wasn’t having any of it. Measuring by touch there was no increase in booster pump temperature so everything was completely safe – well, that’s what we told Sue.
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