I don't think battery technology is common sense...
Me neither. I know it's not. But what _
is_ the more common is what I outlined above.
but burning off the propane from the supply tank after turning off the tank valve, well most people I would think do that even on their gas grills sitting in the backyard...hell maybe i am giving people too much benefit of the doubt....
You're giving people too much benefit of the doubt.
Far as I know, every gas grill manual says turn off the gas as the source first,
then the burners. Some people do it that way, some don't. But I wonder how many people know why it should be done that way?
And it's not because the propane
"will chemically react with the rubber and leetch a light oil." Trust me, if it'll "chemically react" when the heater is turned off and the hose is pressurized, it'll "chemically react" when it's turned on and the hose is pressurized.
It's caused by the same problem as propane conversions in automobiles, sort of, the same physics, anyway, and why the converter temperature in an automobile conversion is so critical. When exiting the bottle under pressure, the propane and whatever contained is (the bottle, the hose) becomes very cold. When gaseous propane is drawn at a high rate, the latent heat of vaporization required to create the gas will cause the temperature of the bottle and the hose to drop. This is why water condenses on the sides of the bottle and then freezes. Same with air conditioning refrigerant bottles.
When the heater (of gas burner of a grill) is turned off first, and then the valve on the bottle, the high pressure gas is trapped in the hose. It will quickly warm up, re-liquefy, and increase the pressure well beyond the rating of the hose. Normally, propane won't "crack" (as in petrochemical refining) below 140 degrees F, which results in a plethora of residuals like the oily hydrocarbon heavy ends, semi-solids, and paraffins, but the rapid cooling of the hose when the bottle isn't turned off first will result in a small amount of these residuals as the increased pressure drops that 140 degrees down considerably. Add to that the ethanethiol (A.K.A. Ethyl Mercaptan an oily substance, cited by the Guinness Book of World Records as the "smelliest substance" in existence) that is present in all LP gas. It's the oniony smell associated with the normally oderless propane.
High pressure LP hoses are specifically designed to allow ethanethiol, and the residuals that bond with it under pressure, to permeate the reinforced rubber at a certain pressure. That's to let you know if you have a gas leak and/or a bad pressure situation. When the heater is turned off first, and then the valve, the increased pressure in the hose will be enough to let these residual oils and a minute amount of ethanethiol escape through the walls of the hose. It's not enough ethanethiol to be alarming, since you've pretty much been smelling it all along. But it's enough to create an oily mess.
Try uncoupling the hose from the valve before you turn the valve off. There's an oily mess for ya. Don't ask me how I know that.
Besides, it was many, many years ago and my curiosity about why a colorless, orderless gas would be that oily got the better of me, hence my education with propane.
It's not as likely in a propane heater or gas grill as it is in a malfunctioning automobile conversion (where compressor oil also come into the mix), but there will be a natural build up of these residuals on the heater, regardless of when you turn the valve and heater off. Turning things off in the right order helps a lot, but the build up will still happen, which is why the recommendation for the gas line filter is such a good one, even if for the wrong reasons.
There, another post just chock full of semi-useless information.