Propane Tank Question
Is this true? ""Propane tanks have a safety valve that shuts if a gas line should break and allow full flow.""
Forum Discussion
ACME excess flow does not shut completely if operating properly.
two safety features are built into the Acme nut itself. First, Acme nuts contain a thermal bushing, which will melt in a fire, and prevent the escape of gasses from the tank. When it melts, it allows the new OPD spring activated shut off valve, which will only allow the flow of gas if a fitting is attached, to pop out and completely shut the flow down. They also have an improved excess flow check valve,
Now to the new style excess flow check valve on the Acme nut that connects to the DOT cylinder's OPD valve. It is really a simple device. Inside the Acme nut, there is a ball bearing check valve that almost shuts off momentarily when full pressure is released by opening the cylinder valve. You should hear a click at that point. It doesn't shut down completely, as that would negate its ability to detect leaks and excess flow from a leak or major line break, and no gas could flow. It closes just enough to allow a bypass of gas that is very slight, about 10 cubic feet or less per hour (cf/hour) flow, as opposed to the max flow of 200 cf/hour. The bypass gas goes into the propane system, and if there are no leaks or broken pipes, it backs up and builds pressure in the gas lines in the RV. When it equalizes on both sides of the valve, the valve opens to allow full pressure up to about a max of 200 cf/hour at 100 psi. Then if you were standing there, you would hear a second click.
http://home.earthlink.net/~derekgore/rvroadiervfulltimingwhatisitreallylike/id44.html
two safety features are built into the Acme nut itself. First, Acme nuts contain a thermal bushing, which will melt in a fire, and prevent the escape of gasses from the tank. When it melts, it allows the new OPD spring activated shut off valve, which will only allow the flow of gas if a fitting is attached, to pop out and completely shut the flow down. They also have an improved excess flow check valve,
Now to the new style excess flow check valve on the Acme nut that connects to the DOT cylinder's OPD valve. It is really a simple device. Inside the Acme nut, there is a ball bearing check valve that almost shuts off momentarily when full pressure is released by opening the cylinder valve. You should hear a click at that point. It doesn't shut down completely, as that would negate its ability to detect leaks and excess flow from a leak or major line break, and no gas could flow. It closes just enough to allow a bypass of gas that is very slight, about 10 cubic feet or less per hour (cf/hour) flow, as opposed to the max flow of 200 cf/hour. The bypass gas goes into the propane system, and if there are no leaks or broken pipes, it backs up and builds pressure in the gas lines in the RV. When it equalizes on both sides of the valve, the valve opens to allow full pressure up to about a max of 200 cf/hour at 100 psi. Then if you were standing there, you would hear a second click.
http://home.earthlink.net/~derekgore/rvroadiervfulltimingwhatisitreallylike/id44.html
