Fuel tanks

[Lynn Eades]

The MkIII carrier fuel tanks are the same Capacity (10 gal) as the other carriers, and I think dimensionally the same.
The 1941 (june) print of the Canadian MkI* (early?) only shows the cap with the valve in it (no breather pipes) The parts book said; Do not order TL12464, to order CTL 410 SA. There are two left hand and two right hand tanks listed.
I'm guessing this cap with the ball and valve in it is spark arrestor set up. The Australian carriers have a spark arrestor in them.

[Richard Farrant]

Originally Posted by Lynn Eades

I'm guessing this cap with the ball and valve in it is spark arrestor set up.

The ball valve stops petrol from escaping when traversing steep inclines, also to seal off in event of the Carrier overturning.

[Lynn Eades]

I too can state the obvious; The MAIN purpose is to allow air into the tank to stop it collapsing as the fuel is drawn off. BUT... when there is vapour pressure in the tank, does it lift the ball and close the valve? (the 3/4 steel ball weight, would hold back a bit of pressure)
Many carriers were built with the sealed cap, and vent tubes.
Were problems with these the reason for the "valved" caps/ non vented tank design?
Which design came first.
Was the vent pipe design o.k. for northern climates, but unsuitable for the desert theatre?
So many unanswered questions

[Richard Farrant]

Originally Posted by Lynn Eades

I too can state the obvious; The MAIN purpose is to allow air into the tank to stop it collapsing as the fuel is drawn off. BUT... when there is vapour pressure in the tank, does it lift the ball and close the valve?

Well, I do not see how it could have been a spark arrestor, that is something you normally get on an exhaust pipe to stop sparks escaping, so I was just pointing out the true purpose of the ball valve, in case you were unaware.

It is doubtfull that vapour pressure would lift the ball enough to close the valve, as it would have to be a surge of pressure, where as vapour would be a slow build up. Only my thoughts though,

[Ben]

I've checked FUC 03. The pictures seem to suggest the MK 1 had the tank pictured in Riche's post, two vents a filler cap and a fuel pick up. The MK 2 picture has vents in the same style as the MK 1 but with an extra fitting towards the middle of the tank. This I assume is the pressure valve!! Don't know how a pressurised system works if it's vented? Or if the cap has a valve what the extra fitting is? the part isn't labelled.

Ben

[Jordan Baker]

The mk2 carriers had a gas gauge on them. Thats probably what you think is a pressure valve.

[Lynn Eades]

Richard, after a quick read, the spark arrestor in the Australian carrier tank, is the mesh strainer, not the valve.
The non vented cap should not have the hole that has been drilled in it. I expect that it has been used on a tank with no vent pipes.
Ben the valve is in the cap, and is closed by the movement of the steel ball.

[Richard Farrant]

Originally Posted by Lynn Eades

Richard, after a quick read, the spark arrestor in the Australian carrier tank, is the mesh strainer, not the valve.
The non vented cap should not have the hole that has been drilled in it. I expect that it has been used on a tank with no vent pipes.
Ben the valve is in the cap, and is closed by the movement of the steel ball.

Thanks Lynn, that all makes sense now