I called a friend still in the business. He's not
been an operator for decades, but he specs the following:
Kero/JetA: 110-120F
#2 Heat 120F
#2 Diesel >120F, he recalls 125 but won't swear
to that number.
That said, the military had their own brews. USAF used to use nasty
JP4, it being laced with tolune and naptha. The Navy would not touch
the stuff, not wanting low flash stuff inside a carrier. They used
JP5, which ISTM is higher temp JetA.
The AF has since wised up and gone to JP8, which I believe is
almost identical to JetA. Exception {past} -- the Blackbird used
JP7, much thicker {"3 in 1 oil" feel, I'm told.} and higher flash.
In any case, there is no practical difference in a building tank
housing any of the top three.
Regarding the pressure difference issue.... The tank by the generator
[aka "day tank"] is filled from below. If you have a 30 story building,
with a roof generator, that's ~~150psi.
If the line ruptures on floor 3....
One approach is coaxial lines: the inner is the high pressure "up"
line; the outer the overflow return. If the inner ruptures, it will
be into the outer....