I just had the compressor guy in to service my compressor which we have to have done yearly for insurance purposes- the resevior is about 5 foot long and about 3 foot in diameter and operates at 120 PSI.
Well, he had to check the relaif valve and strip the big bolt off it to look inside for rust n stuff.
Now... as you probably know with compressors they should be drained every day cos they accumulate water from the atmoshere as the air is compressed. Usualy you have a hose and get about 1/2 gallon of water every day depending on atmospherics.
Here's the interesting part... he was drawining all the compressed air from the tank and it seemed to run out of air. But the guy didn't continue to strip the unit down- I asked him if it was empty. "No" he said, "What happens is the remaining water vapour can freeze as the tank's decompressing so you think it's empty of compressed air, but the ice has frozen he outlet valve closed".
I had a horrible vision of undoing the big nut on the end of the tank and finding that there was still 120 PSI in there...
Food for thought! Just thought I'd share.
I love deadlines- I like the whooshing sound they make as they fly by.