UBUC

The Static Compressor

 The club has our own static compressor that we use to fill our cyclinders to 232bar. It has evolved somewhat over the years with people coming up with new ideas to improve it to the point that we can leave it pumping and it will automatically stop once finished or if a problem should arise. The key points of the compressor are:

• The manifold setup allow us to leave it pumping 2, 7 or 12 cyclinders at a time.
• Once the compressor reachs 232bar it will automatically switch off, if it doesn't there are pressure relief valves that start releasing gas at about 235bar which prevents overfilling the cyclinders
• If for some reason the compressor can't reach 232bar, commonly because there is a blown 'O' ring so the compressed gas is escaping, there is a timer switch which will cut off the compressor
• On the right as you enter stores is an emergeny shutoff button which will kill the compressor. Handy for blown 'O' rings. You have to twist to disengage once pressed, if the compressor won't start check this hasn't been accidently knocked.

How To Use the Compressor

Put the bottles in place. Let out a short blast of air from each bottle before connecting the compressor hose (this is called snifting). Normally, twelve bottles are connected as shown. V1 links to the compressor and V2, V3 and V4 are purge valves enabling smaller numbers of bottles to be pumped. Gauges G1, G2 and G3 are the gauges for each group of bottles. At this stage, V1 and V4 should be closed but V2 and V3 should be open.

When all the bottles are connected and V1 and V4 are closed, slowly open one bottle which will pressurise the system. Listen carefully for any leaks from any bottles not connected properly or with dodgy O-rings. If all is OK, slowly open each bottle, and allow the system to pressurise.A couple of turns is enough you do not need to fully open any valves on the compressor. Open the valve slowly.

When everything has stopped hissing open V1, which connects the now-pressurised system to the compressor. After checking the oil bubble (see top), press the Green start button and everything should start pumping merrily. Whenever 232 bar is reached, the compressor automatically shuts off but keeps the system at pressure.

When the compressor has finished, shut off V1 and close all the bottles. The system can then be purged by opening V4 as shown. After an initial blast of air, the gauges should quickly drop to zero. If not, then one of the bottles is not closed properly. Close V4 and check. Otherwise, remove the hoses and place the bottle in the FULL section of the stores.

Topping-Up already pumped bottles

The compressor will top-up already full bottles to 232 bar, however the green button won't work if the G1 reads higher than 190 bar (as shown) with V1 open. Connect up the bottles and pressurize the system with one bottle as before. This ensures there are no leaks. Close this bottle again and open V4 a bit to lower the pressure in the hoses. Open V1 and ensure the G1 reads less than 190 bar. If not, open V4 again. Press the green switch to start the compressor and then immediately open all the bottles. The compressor will automatically shut-off as before

Further Notes

• Try not to fully open any valves on the compressor as it causes more wear and tear on the valve seats. There will be more then enough gas flow with just one full turn.
• Only open pillar valves by a couple of turns, again - there will be enough gas flow.
• Whenever gases change pressure a temperature change will occur. For a number of reasons, you should attempt to minimise this. i.e. don't equalise the pressure between a completly empty cylinders alongside full cylinders.
• Slow gas movement is best. Slowly open all valves at all times especially when there is a large difference in pressure on each side of the valve.
• It is possible to add and remove bottles in certain combinations when the compressor is running, resist from doing this as its not possible to hear if there is a leak when the compressor is running.
• When using the Nitrox clean filter (not explained here), never pump with the full power of the compressor. This will tunnel the medium.
• Please do not use the Nitrox clean stuff without signing the sheet and without being fully shown how to use it.