Mine is butane. I am a GM dealership technician, we were warned about electric soldering irons on air bag systems years ago. We were told the small current can deploy the bags. I have not used electric on any circuit boards or electronics since I learned this.
A good friend is also a GM dealership mechanic. He told me that they would be help liable for the cost if they used an electric soldering tool on an air bag system and it went off. He used a butane iron on air bags too. Lots of mechanics also have Weller soldering guns for other uses.
Some of the old school Princess and Imperial soldering guns I own have a ground.
I have a couple of grounded Weller desoldering irons too. The desoldering irons have a hollow tip and a squeeze bulb to suck out the solder. Not much good to clean up terminals with excessive solder, but they work well on old printed circuit boards.
