what ones have people used and passed IVA with?
I've got a cheap one, not really sure its right though... its more a one way valve. won't let gases both ways though, or is that ok? just as long as fuel doesn't come out when if its upside down?
do they even check it?

manual says you have to let gas pressure OUT of the tank

the wording is
"The fuel tank must be fitted with a vent (to permit release of a pressure build up) which does not exit on to the exhaust or into the vehicle or be situated at such a height that fuel would be likely to leak when the vehicle is driven."

so does it need a valve? if it was upside down, can it leak everywhere and be fine? i'm a bit confused by this now...
any cars i could have one from? i've got an 8mm in/out put on fitting on the top of my tank going spare for it

We've passed SVA with a simple plastic one-way valve. I did remove it after a while and fitted a proper (mocal) one, because the tank was building up quite a bit of pressure.

got mine from here, worked well

http://www.tntracing.co.uk/product_view.php?id=8472

My one-way valve was configured that it lets air into the tank, so I it should not have been SVA compliant Guess they don't look as closely to stuff like that.
Still, I wouldn't go for just a one-way valve; it'll be a problem either way round. I've seen cars stall because of improper ventilation.

@ below,
That's the one I have now

[Edited on 26/1/12 by rost]

see this one, this is the type needed link

Easiest solution is a piece of pipe routed so that it cannot leak regardless of tank orientation.

Something like this------
[img]
breather hose [/img]

Is a coiled pipe still IVA ok? - like this one ...

taken from http://www.r1ot.com/mar07.htm




[Edited on 26/1/12 by monkeyarms]

All I had on mine was a vented cap from an old Mini and it was fine, you don't need a valve as long as the petrol can't spill onto anything hot.

From the IVA manual....

12. The fuel tank must be fitted with a vent (to permit release of a pressure build up) which does not exit on to the exhaust or into the vehicle or be situated at such a height that fuel would be likely to leak when the vehicle is driven.

So I would think most of what has been suggested in this thread meets IVA requirement

awesome cheers everyone will go with daviep's method then or even the coil. seems quite good too. i'll lead it to the left as the exhaust is on the right of the tank, which is where the outlet points...
the vent connection is in the middle of my tank, which means it needs slightly more thought on the path it takes, but can still work

then maybe go with Joes mocal valve later. just wondered what, say, Ford or vauxhall use on their cars to borrow one

[Edited on 27/1/12 by blakep82]