Originally Posted by unifreck
A few years ago early in my RV adoption phase, I took my Interstate to have the propane filled not really knowing how it was done. Unfortunately the lowest employee on the pay scale (just started several days before) was asked to do the filling. He hooked up the nozzle and let her rip not knowing there was a pressure relief valve that should be opened ((all propane turned off, and no active burners). All of a sudden a loud NOISE and PROPANE MIST , activated LOUD propane alarm and high pressure exhaust noise. Totally blew a hole in the line going to tank, there is a back pressure valve on the tank, so no propane escape from it. It took several weeks to find AIRSTREAM no longer stocked the part and have one fabricated. Talk about learning under "fire" , I will never forget that lesson and neither will the employee who now is the Service Writer at that RV shop and goes out of his way to help me .
We all learn a little more everyday and thanks to this FORUM I've learned more than a little.
I've had them trigger blow-by, if that's what you're referring to. Not a mist but a jet stream of escaping propane pressure.
On this issue generally, it has become my practice to strongly warn the attendant that he's only going to get in 3 or 4 or 5 gallons (T1N Interstates have a 6-ish gallon tank). They don't realize how small the tanks are on these rigs, so they expect to be filling much more. When no more goes in, they tend to want to force the issue.
Also on that note, watch for places that have minimum fill charges. Sometimes they'll want fifteen bucks just for topping you off two gallons. I've had my best luck with our local U-Haul rental place as they charge by the gallon with no minimum purchase.