@Rod1. thanks for that info. this would account for the reduced capacity in the drum.....it aint a "drum" it's a portable bunded tank that
lookslike a drum
@ F900dx there's a world of difference between storing Diesel or paraffin (all lumps as "fuel oil" and Petrol/ Avgas.
UK storage regulations are strict on the storage and distribution of the latter...As Rod confirms, you
do need a license to store a largish quantity...as with bottled gas, the regulations become quite onerous once you're over the "domestic" limit.
I'm sure the fire-brigade would not be best pleased to answer a shout to a suburban semi, only to find 30-odd gallons of highly volatile fuel...presumably the container has a fusible safety-plug...otherwise it's a potential bomb. (much more dangerous when empty,as the fumes are explosive...as with underground tanks, full to the brim is safest!)-we had to chain and padlock the fill and dip-tubes even though the average thief wouldn't have a set of keys to lift the manhole cover anyway!
A bund is simply a posh spillage catcher...usuallyhas ~20% bigger volume than the bunded tank.