Originally Posted by RnRollie
doesn't that have a big chance of going BANG in case of a leak (+ a flame/spark)?
Not that you'll care, as you'll probably be in a state of euphoria (if not dead) if you didn't notice the leak.
Yes it does.......but I've been researching and thinking out how to do this safely for over a year, brain storming on various forums.......I'm only starting the build now as I'm completely satisfied I've covered all the angles.....and I'm doing this project in a shed not the house in case of un-forseen eventualities.
Leakage of butane out of the system is in fact the least likely problem as the system will be under negative pressure or at maximum atmospheric pressure and can be guarded against by ventilation and a gas detector/alarm
The most concerning problem is leakage of oxygen bearing air into the system as during use it will be under negative pressure, which could lead to an explosive gas mixture within it, but without going into detail I've covered all possible angles of air ingress, even down to tracking in through along the length of the cable sheaths.
Flammable gases have an upper and lower explosive concentration, for butane the upper level is about 10%, above that concentration there is not enough oxygen present for ignition even if an ignition source is present. The gas in the chamber will be close to 100% butane so a long way of from the upper explosive limit. Regular purging will ensure the concentration is kept high.
Also the tendency of the butane to pool at the bottom of the chamber and air rise to the top because of differing density could mean that somewhere between the top and bottom of the chamber could be a gaseous layer of the correct mix for ignition....that layer will be disrupted prior to system start up by starting a fan (brush-less hence spark-less) at the bottom of the chamber that will mix the layers.
I was also concerned about material failure, plastics cracking etc, which is why I've gone for a completely metal, chamber, pressed steel fluid basin (seamless), and flexible stainless steel connection hose which will transfer the liquified butane between the pressure bottle and chamber.
Before loading the system with butane on first assembly it will first be purged using oxygen free nitrogen again to ensure that can be done safely.
So yes you are right......there are potential dangers....as there are driving a car with a tank full of gas....and I'd not encourage anyone to do this without thorough research.....but I'm quite satisfied I've covered all the bases or I wouldn't be doing it.Edited by technogiant - 8/6/13 at 2:18am