Dutch_12078 wrote:
Just to add a bit to Doug's excellent post, the bleeder valve does NOT "bleed air" from the tank. A properly purged tank has no air in it. As Doug noted, the bleeder passes propane gas until the liquid level reaches the valve at the 80% full mark.
I recommend "Propane 101" to anyone wanting to learn more about their LP tank or cylinder setup.
After 40 years in the LP business I second your reference to Propane 101 as a good primer for general information regarding tanks and cylinders used in the storage and transportation of LP gas.
The info provided is well presented and should be helpful to most users. It would have been more useful if it had addressed more specificly the tanks used on our motorhomes and as motor fuel tanks for some vehicles. Rather than me typing a lot of words that will only confuse, I would suggest that anyone seeking additional knowledge on the subject would be well served by Googleing RV Propane tanks. One of the more prominent results will show images of various tanks and a piping drawing of an ASME tank, typical of an RV tank.