1. You've run out of gas. Major problem.
2. Gas lines will never set if there is just one gas tap even partially open. (It only takes one child to fiddle with a tap to cause problems.)
3. You've gone outside to the gas cylinder, undone the cage, made sure the gas cylinder is turned on, pulled the little thingy to make sure the gas is set in the line, gone inside and shut all the gas taps, turned the key and pushed the button and watched the pressure gauge do ....nothing. rechecked all the lines and come in again and still nothing. So you recheck all the gas taps again to make sure they are all closed ....still nothing.
Then as you look at the teacher's bench it dawns on you that the emergency gas switch has been pushed down by some charming child, 
You release the emergency switch and push the gas switch and the pressure gauge goes up. 4. You have not used the gas for some time and when you pull the ring pull you stand there for a month of Sunday's while the line is setting. Seems that the gas can evaporate in the line during hot weather which makes it difficult and time consuming to set the gas lines to the labs.
5. Then you have the gas which meanders through the line taking forever to get around the room to the far side gas taps. The last gas tap on the circuit just blows out air until the gas gets there. (But Miss, the Bunsen isn't lighting up.) Where is the emoticon for tearing ones hair out?
So for those of you out there having problems, been there, done that, tell us about it. Share the frustration and we may solve a few problems.
