18 replies to this topic

[cardboard]

Hi guys,

I am studing automotive engineering at loughborough university and to cut a long story shirt we have had to design an amphibious vehicle, this vehicle will have to tanks one on each side. they need to drain simultaneously but be independant of each other, i.e. fuel cannot flow betweem them. do the mini cooper tanks work on a similar idea?

can anyone help, any ideas who to do this?


thanks

Edited by cardboard, 14 February 2008 - 10:24 AM.

[Turbo Nick]

twin tanks in a mini usually have a pipe running between them to balance out the fuel level, no idea how you're going to do it i'm afraid.

[cardboard]

cheers mate does anyone know of any other vehicles that use more than one fuel tank and how they work or any ideas how we can do this?

cheers

[ian]

Try looking at a xj6, they have twin tanks.

Not sure how they worked it, just know you have a switch on the dash for swapping from left to right tank.

[nobbycameron]

how about using a one way valve? or two.

have a one way valve on the bottom of each tank and then join the two tanks together after the valves, this will mean that they will drain simultaneously but fuel willl not be able to be passed between the two,

just an idea

[cardboard]

with the vehcile on water and the fuel moving do you not think it will draw more fuel from one tank over the other

[CharlieBrown]

Have a look at aircraft design, might be a bit of overkill though.

As in a electronically metered fuel system.

[mk3 Cooper S]

Try looking at a xj6, they have twin tanks.

Not sure how they worked it, just know you have a switch on the dash for swapping from left to right tank.

They had twin tanks and pumps and a switch on the dash to change them over.

[lrostoke]

Landrovers can be fitted with twin tanks, most common way is to fit a manual change over switch, the switch also changes the wiring so that the fuel gauge works to show level of tank being used.
Only way of having twin tanks draining at same time but with no direct connection between is as mentioned a one way valve on each tank outlet going into a y piece then a single line to the engine.

[Dan]

As Charlie says, look at the design of aircraft fuel systems. They have to keep the tanks isolated for the same reason as the boat will (weight distribution and trim). Light aircraft would probably be more applicable than a civil airliner, try looking at a company called Andair, they make fuel selector and distribution valves for light aircraft and general aviation. The one way valve idea above is the way forward.

Also, moved to general chat.

[dklawson]

I don't know aircraft systems but I know pneumatics.

As Irostoke said, you need a one-way (check) valve in the lines from each tank. This will allow the fuel to exit one tank without being able to enter the other. You will have to select a pump (or pumps) that can develop sufficient vacuum to open the check valves. You select check valves for their material of construction and their "cracking" pressure, typically at least 1/2 PSI. You may be able to find some check valves that will work by gravity closure if you remove their internal spring.

Emptying both tanks at the same rate will likely require a level sensing system in both tanks and two pumps that can be cycled on and off as necessary to maintain trim.

[mini_turbo_pete]

With light aricraft you have got the tanks that are connected upto a manual switch in the cockpit that you use to select which tank you want the fuel to come out.

The Mini's and Jags have got a pipe that rund between the two tanks to balance the fuel out between the tanks.

your best off with one way valves coming out of the tanks.

Have a look at the fuel pump etc on a rover 75 as these have a split tank with a fuel valve system in them.

Edited by mini_turbo_pete, 14 February 2008 - 01:13 PM.

[mk1leg]

I would think on a water bourne vechile and having a tank on each side you would have them drawing fuel at same time or you will have trouble with bouyancy problems.........................

[cambiker71]

I'd guess that the easiest way would be a one-way valve coming out of each tank to a central T piece, this would allow fuel to drain out from each tank but not back in, this way it wouldn't allow fuel to flow from one tank to the other either.

[Bigfoot]

How on earth do you measure the fuel level in a tank on a floating platform? Seeing as it's constantly sloshing around... Can't get my head round that.

Only way I can think of to have the tanks simultaneous yet independent is to have a little pump from each tank, both pumping at exactly the same rate, feeding into a small reservoir which feeds the engine. So that so long as the tanks started at the same level, you would be controlling the rate at which fuel came out of each one, so they *should* balance.

Basically, two very carefully regulated uni-directional valves, like most folk have said.

Am I stating the obvious again?...Or worse, stating exactly what someone else has already said...