DISCO DAVE'S TUNNEL GUIDE
Oxygen
It's day 4, the tunnel's going well. The first piece of shoring went up without too many problems and the baggers are working hard. Yet today the digging seems more difficult. Yesterday wasn't easy but today you're stopping and breathing heavily after only 10 minutes work. Go to the surface and let a colleague have a go at digging. If they experience the same breathlessness then you'll soon need a fan to pump oxygen into the tunnel. Digging until the air becomes so thin that it's impossible to continue will mean you'll have to wait on the surface for a fan and piping to arrive. You should therefore continue digging at a slower pace asking your colleague (or going your self) to go and acquire what's needed. (Ideally of course you'd have the piping etc on site before any diggings started). You'll need the following:
A 12 v computer system fan (available from any computer retailers), a large roll of gaffer tape, 2 crocodile clips, a small length of electrical wire, insulating tape, a large rectangular margarine tub or similar and piping. Mains duct pipe commonly used on building sites is perfect. The pipes strong ribbed plastic design means it will stand up to any collapse. Yet at the same time is very pliable and permits a trapped tunneller to puncture a hole in between the ribs for air. The only downside is the pipe is expensive to buy.
(A)Extend the wires of the computer system fan so the positive and negative leads are each around two feet long. Then cover the connections with insulating tape.
(B)Take the lid off the margarine tub. Then cut three holes in the tub one at each end for the half-inch diameter pipe, the third in the side for the two wires to power the fan.
(C) As the fan will be positioned in a bunker on the surface the air inlet pipe should be long enough to stretch around to the roof of the bunker. Paint a clear sign to hang from this pipe to inform humans and bailiffs what the pipe is for. Push the other end of the pipe into the end of the tub. The tighter the fit the better. Then gaffer tape around the hole so it's as air tight as possible.
(D)The air pipe that leads down the tunnel can now be cut to the desired length and attached to the shoreing or dug into the wall. (See MIB section "The Other side" Ch 22 before doing this ). Use a pair of gloves and a knife that's been heated over a fire to slice through the plastic. Rather than cutting the pipe with a saw that will leave small plastic chipping on the rim and in the pipe. Like with the inlet pipe position the pipe into the other hole and gaffer tape.
E) Place a thick piece of cardboard on the floor of the tub. This will act as a cushion for your fan.
F) Rest the fan onto the cardboard and tape so it is in an upright position. Feed the positive and negative leads through the hole on the side of the tub. Attach a crocodile clip to the end of each wire, and then tape around the hole.
(G) Tape a thick piece of cardboard to the inside of the tubs lid
(H) Put the lid onto the tub. The cardboard on the lid will remove the gap from the inside of the lid and keep the fan stable. Tape around the lid of the box. Then test using a car battery. All going well the fan will hum softly to itself as it pumps a sufficient steady flow of air down to you.
(I) Bury the pipe* into the wall or floor of the tunnel. Extending it when necessary by gaffer taping on an extra section.*(See communications prior to doing this)
Allow the fan to run during workdays. With the last person to leave the tunnel remembering to disconnect a crocodile clip. If people are sleeping in the chambers allow the fan to run for 2 hours before people retire to bed. Leaving the fan to run all night is unnecessary and a waste of battery power. If, while you sleep, the oxygen level drops to a dangerous level, your brain will give you warning by awakening you thus allowing you time to get out of the tunnel. This may seem hard to believe but it's true none the less. Carrying a small pocketknife is a sensible precaution. If the tunnel collapses blocking you in a small space by puncturing the air pipe you'll get enough oxygen while waiting for help to arrive. Baggers should take note of what a digger has eaten that morning. Remembering that as well as blowing stale air back out the tunnel, the distinct aroma of the diggers bake bean breakfast will also come back at you.
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