I don't know why an AL80 is actually 77.4 cu.ft. but I have noticed that all the cylinders are equal to or lower than what you might expect. An AL63 is actually 63 cu.ft.
I can see people in marketing having the conversation:
"I don't think AL77.4 has a good ring to it."
"How about AL77?"
"Nah, it has more then 77 cu.ft. We should round it up to AL78."
"Well, as long as we are rounding up, why not just call it an AL80?"
"Sounds good to me."
"Done."
What confuses me is:
HP65: 66.4 cu.ft.
HP80: 81.0 cu.ft.
HP100: 99.5 cu.ft.
HP119: 123.0 cu.ft.
HP120: 120.6 cu.ft.
HP130: 131.4 cu.ft.
They round down everything except the HP100 plus the HP119 is larger than an HP120. Maybe someone at the cylinder manufacturers are conducting a psychological experiment on us.
I can see people in marketing having the conversation:
"I don't think AL77.4 has a good ring to it."
"How about AL77?"
"Nah, it has more then 77 cu.ft. We should round it up to AL78."
"Well, as long as we are rounding up, why not just call it an AL80?"
"Sounds good to me."
"Done."
What confuses me is:
HP65: 66.4 cu.ft.
HP80: 81.0 cu.ft.
HP100: 99.5 cu.ft.
HP119: 123.0 cu.ft.
HP120: 120.6 cu.ft.
HP130: 131.4 cu.ft.
They round down everything except the HP100 plus the HP119 is larger than an HP120. Maybe someone at the cylinder manufacturers are conducting a psychological experiment on us.