there's abit about fuel management...centre tank runs to x -thousand
lbs./kgs and then stays off until main tanks reduce to y-thousand, then
centre tank pumps run again.
Not quite, to be more precise the centre tank override jettison (OJ) pumps are switched off manually at approx. 800kg of fuel remaining in the centre tank. Float-operated shutoff valves prevent fuel scavenge when the main tanks are full. When the main tanks reduce to y-thousand the float-operated shutoff valves open and the fuel scavenge jet pumps will start scavenging (operated by motive flow from the boost pumps) the remaining fuel from the centre tank. The centre tank OJ pumps remain switched off.
Centre tank fuel is relatively warmer than main tank fuel because most of the centre tank is situated above the airconditioning system which radiates heat, it is between forward and aft cargo compartments, and the passenger cabin is above it. Hence, main tank fuel is relatively colder than centre tank fuel.
Green-dot