I worked on an air force base refueling acft. Did it for the past 19 years till i retired last Sept. Also did it in the USAF for 20 years and 5 days. The job also included ground fuels and working in tank storage systems. In another web site I was going to use just Gaspasser but it was already taken so GPD was the first thing I came up with that worked and it kinda stuck with me.