You have 4 red lines and two black lines going into the surge tank. What are the lines carrying and what does a surge tank do?
the two black lines are coolant lines , feeding a hot fox tank heater to heat the surge tank.same loop has a 30 plate heat exchanger, a heated fuel filter and a heated water seperator.
two reds are engine in and return the other two reds are feed in and a vent line back into the main wvo tanks. the level in the surge tank is controled by a level switch , that activates the lift pump at the main tanks. in case this fails and overfills i returned the vent to the main wvo tanks, so it will back fill.
the surge tank is only there , to feed the engine. this way only 17 gallons have to be heated and i have faster switch over times from diesel.also with the amount of fuel a detroit is spilling allready at idle ,its would take some huge inside dia fuel lines to not have to much restriction when on wvo with lines longer then 20 feet. on my other vehicles i found that when driving short distances and having lots of heating and cooling cycles on a large wvo tank , that i have signs of condensation (water build up)
the only flaw in my system , is that i kept the stock secondary fuel filter after the gear driven fuel pump.
i kept it as insurance in case my pump fails and to keep temp changes at switchover slow.the temp diff should be no problem on a detroit, with the gear pump mounted to the block and fuel running in the heads. but on some ve pumps i had problems with seized plungers at switchover.
the only problem i have due to the filter is that my purge times are longer to flush also the amount kept in the filter.
before i stop and switch over to diesel, i turn of the transfer pump to the surge tank, and run it down to half. then i switch to diesel and let the return flow into the surge tank. so the wvo and diesel mix goes into the surge and not to the main diesel tanks. after a minute return also switches back to the diesel tanks and the bus runs on the main diesel tanks, ready to shut off.
my main wvo tanks are only kept at room temp (bus inside) and the fed lines are bundled with the coolant lines that go to the front under dash heater and to the heat exchanger for the shower.
i also have my webasto diesel fired water heater set up , that its looped into the engine and then into the wvo pre heat circuit. so when my shower water is ready, my engine is also at 180 together with the wvo and after airing up im ready to switch.
with that setup i usually use between 20-30 gallons of diesel on a 2000mile trip. most of the fuel used by my webasto and espar heaters and the generator. next step would be to have the gen set also connected to the wvo source. maybe i have that ready till summer when i need the power for the ac.