Plastic fuel tank question

[Peter2673]

Hi

In recent changeable weather I've noticed that a plastic fuel tank (12.5l genuine Mercury), part filled and stored in a garage some way from the house, has its sides collapsed in after a cool night, and bulges at the end of a warm day.

When the sides cave in there are quite sharp creases at the tank's corners.

Will this happening repeatedly weaken the tank?

How do you avoid it?

I've considered leaving the air vent open but there's a safety issue with that if. Vapour escapes.

Thanks

Pete

[Fenlander]

Pete you have to make your own choice here.

I've seen the most dramatic sucking in and bulging out of tanks over the years so I now garage store them with the vents cracked a tiny bit. The garage is well ventilated, cool and not connected to the house. I never smell any fumes from the tanks.

When travelling the tanks I always do the vent up tight.

[willk]

Pete - good advice from Fenlander there!

Chances are you already have another vented petrol tank in that shed - think lawnmower. The vent should be opened only the VERY smallest amount (do this when it's under slight pressure and as you open it you can stop at the very first release). This will allow equalisation but very little petrol vapour will follow after that. Logic says to store the tank in the coldest lowest part of the shed out of direct sunlight and away from sources of ignition (heaters, furnaces, switchgear). I keep mine beside my DIY cider "cave" - what could possibly go wrong?

[Max...]

They usually inflate/deflate a little but should not be much unless you are leaving them in somewhere with larger temp differences, if you are seeing sharp creases that is surprising as normally the material is quite stiff. Less petrol in there the worse it is.

[jeffstevens763@g]

The only reason the tank has a breather screw is because the fuel is so close to the top of the tank and has be shut for transportation. in use bouncing about in the boat you can get a slight bit of spillage but nothing to worry about to be honest I don't shut mine unless their full and transporting to and from ( when open just cracked).