Originally Posted by email@example.com
It is not a good idea having a rubber hose pressurized w/ 15psig acetylene though. Like I said that stuff is very unstable as a free gas.
15 PSI is pushing the limit but sometimes it is necessary such as with a large cutting tip (Victor no.8), large gouging tip or a heating tip (a "rosebud" not a large welding tip) but these are special situations and a backflow valve should always be used. Also hose size plays a big part in determining how much pressure is required to deliver the flow needed but if over 10 psi (preferably less than that) is required to supply the"normal" size tips, no.5 or smaller Victor or equivalent cutting tip but never a welding tip, then a larger hose may be needed. Attempting to use large equipment with a small hose, a no.6 tip with a 1/4" hose for example, and turning up the pressure to get enough flow is dangerous and even if you don't get hurt the backfiring that is likely to occur will damage your equipment. For auto type work I can see no need for Acetylene pressure to exceed 6 or 7 lbs of pressure and most likely a person will not need that much likewise 20 to 25 PSI on Oxygen should just about cover anything anyone is likely to run into and with a welding torch keep both pressures as low as practical. In any case NEVER!!! exceed 15 PSI on the Acetylene and don't even approach that much unless absolutely necessary, IMO those regulators should be mechanically limited to less than 15 PSI but they are not and they will easily turn up high enough to get you hurt or even killed!
One thing to watch for, and it happens WAY to often, is when a tank runs low and the pressure starts to fall some idiots (and I do mean IDIOTS!) will turn up the regulator in an attempt to get more gas out of the tank! I think most anyone who has worked around welding and cutting has seen people do this very STUPID trick and what happens is they (or someone unsuspecting) will change the tank to a full one and then the regulator pressure can be dangerously high or even rupture the gauge, when switching tanks the regulator should always be turned to zero pressure but most of the time this is not done. It is a good idea to get in the habit of turning the adjustment screw all the way out before switching tanks and then resetting it after the valve has been opened. NEVER EVER turn the adjuster in when the tank is low not even to "check" it (the usual excuse for doing so
) but I have seen this done time after time, people when the damn tank is empty it is EMPTY and you can screw that adjuster all the way in and it will STILL be empty!