Hello Mr. Tore,
I obviously forgot to consider the header tank into the equation in the instance of a fuel pump failure. That's why I have you as the expert! I didn't realize they turned off the header tank pressure to the internal fuel oil storage tanks on the surface (I only thought they did that when they dived the U-Boat); that would make sense because that would be one less valve to worry about when a dive situation is called for! However, the header pressure to the external tanks in the compensating mode to FBT 2 and FBT 4 can not turned off. (I don't think?).
I need to STOP guessing!
Mr. Tore, I have searched the internet for many hours today and I cannot discover what the head pressure from the fuel oil pump is to the injectors. If you know the answer to that question, then you can set me straight. It looks like the header pressure can vary depending upon the height of the water in the internal fuel oil storage tanks. So this may affect the head pressure to the injectors as well??? Internal tank 1 has the height level much higher because of the side walls, but Internal tank 2's height is limited to the control room's deck. Would Internal tank 2 be the only tank to select to by pas the fuel pump if it provided adequate head pressure to the injectors?
Regards,
Don_
PS - I did fine this gem of info...
A standing order states that when using Schnorchel U-boats may only use fuel from the external tanks. Fuel is pumped from the internal tanks by using diesel cooling water, the pressure varying with the depth of the boat; if the boat is at 14 meters (46 ft.) the pressure is 1.4 atmospheres. If fuel is pumped from the internal tanks with cooling water at this pressure the tanks are subjected to a pressure greater than that for which they are designed.
By approximate and experienced handling, however, ("cracking" the appropriate valve) fuel can be pumped from the internal tanks, but accidents are likely to occur and this may have been the reason for the order.