I had an issue where I had to check fuel flow through a Model J. I was outside in the parking lot so I thought I was safe from any kind of ignition source. Because of where the Model J was mounted, the only option was to let the outgoing lp from the regulator bounce off the cold engine block. I applied external vacuum to the VFF-30 & the fuel began to flow. All of a sudden- I saw bright light & smelled burning flesh- then the pain set in. Never knew that static electricity was a factor in propane- almost ended my career.