std "grill/BBQ" tank aka 5 gal or 20 lb tank

17 lb to 18 lb empty, 35-40 lb "full"

add 4.24 lbs per gallon in the tank, 4.8 gal is about the
limit with an OPD valve. Need space at top of tank for
expansion on hot days.

tricks, use electronic platform scale, place empty tank, hit
"zero", get it filled and read how many pounds remain, +/-
if tank temp is hot or cold. we use this on our small shop
heater tank.

-- larry/dallas