Vapor Return Valve: Also called the vapor equalizing relationship or vapor equalization valve, this feature is required on all ASME propane tanks. They tend to be deployed in the event that the liquid while in the container will become pretty overheated and have to be evacuated with the container. Area: https://1000-gallon-underground-p99999.widblog.com/81101822/the-fact-about-propane-tanks-near-me-that-no-one-is-suggesting