No (I'll have to see the finished thing), not an exact one, but it'll probably be in the area of 750 mil-950 mil. Highest it could go is 1 bil, but I doubt it'll be that high.
For exploding gases, use the field from Sigma-13. It comes with the gases, then you can edit the gases damage, if you want it to do more. I can give you exact field names when I get back to my laptop.