greetings humans.
certain gas providers seem to be ripping off the general public with bottled gas. When you think your mig or tig bottle are empty, check and see if it has a spring loaded valve on the inner of the valve body on the cylinder where the regulator screws in. If so get a small screwdriver and push it in with the tap turned on. If gas escapes then you know there is still a small amount of gas left in the bottle. When this happens then you can get a piece of 1.6mm filler wire about 30 mm long and bend it about 5mm fron one end at right angles. Carefully place this between your regulator and spring loaded valve, then screw your regulator on. This will open up the spring loaded valve giving you the gas that you originally paid for. Remember that you usually only run out of gas halfway through an important job and it really pisses you off.
cheers BLACK DUCK
this is to maintain a certain residual positive pressure in the cylinder. if you totally empty all the gas, ie have equal pressure inside and outside, it is possible for the cylinder to suck moisure laden air and rust on the inside, rendering your cylinder useless. It is common for divers tanks to have to be tested and inspected should they ever fall below 50bar pressure, (ie greedy divers trying to get another 5 minutes down time) for the same reason. what you're proposing is a truley false economy.
