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LPG Tank fitting


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With my newly acquired V8 powertrain which came from a rangie, I have a 120l tank. For those not familiar with these, they are quite large!! Ideally I would have sill tanks, but as my budget has been blown already I don't really want to fork out another £400 on tanks right now when I have a good/new one.

So, Having measured up the 110, I have a couple of practical options. (I do have a Stako frame and straps):

1) To fit widthways behind the rear seats. The frame can be secured on the wheelarch boxes, but will be suspended between these. Are there any regulations that say it cannot be held by skyhooks in the middle or needs a certain number of bolts to fix?

2) To run along the wheelarch box on one side (drivers is easiest). But it seems rather a lot of weight (quite high up) to be on one side, especially when just driver in vehicle.

So, beggars can't be choosers, but I do want it secure and safe.

Your thoughts?

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Can't say that I know much about 110's but I'm thinking that the skyhook :D option would be bolted to aluminium wing boxes? I think that with (probably) a couple of hundred kilos of gas & tank you might like to find something more substantial to bolt it to in case of a decent shunt... Is there any way you could fab something to go through to the chassis perhaps?

Personally I will be bolting my 80ltr tank down to my (steel - in the rear footwell :) RRC floor with 8 x 8mm bolts with spreaders on the other side, but when it was previously 'professionally' fitted behind the rear seats it was just bolted through the aluminium floor with four bolts and I wasn't happy about it at all. I bet most are fitted like that though.

Sorry - a bit of a rambling reply with no real help, just thinking out loud.

Rog

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My tank (Before removal and disposal - reverted back to the real stuff only.... ) was bolted to the floor behind the rear seats. No spreaders or additional strengthening. Was only 65 litre tank I think but still heavy beast...

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Thanks for the replies,

LS26 - Your 'ramblings' are my thoughts as well, hence the question really. I cannot believe that there are no regs about securing what is a very heavy tank, to something structural. Apart from using the entire loadbed floor where I could probably find a crossmember or something, the options I have seen seem to use the wheelboxes. I will get under it and have a better look.

Mr Bean - the tank is a cylinder 400mm diameter and 1097mm long with 120 litre capacity. Basically the full length of a 110 CSW wheelbox (or load area).

Any more bright ideas?

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COP 11 (code of practice guidelines) should be used for the installation of LPG systems in vehicles. This states that the tank and mountings should be able to withstand a 30g deceleration force.(30 times force of gravity)

If you have a big tank, and it is only secured to the birmabright floor with a couple of spreading washers, there is no way it would stay put in a big shunt or roll over. I wouldn't fancy wearing an LPG tank for a hat!

My suggestion would be to link the tank/floor mountings to the chassis with some additional steel.

Regards,

Diff

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Guest WALFY

This states that the tank and mountings should be able to withstand a 30g deceleration force.(30 times force of gravity)

So how do they determine whether it'll take that sort of force. A very subjective descision. On both parties. I agree though, a couple of big penny washers aren't going to be sufficient.

Playing devils advocate here. If you fill up you tank with 120l of gas but really it's a fluid and you then smash your car up at 100mph on the motorway that tank will very quickly leave the vehicle and cause some severe damage to anyone in it's path. I've had 2 cars fitted with LPG systems and looking back now neither would of passed the 30G test. Both were fitted using the fixing kit that came with the tanks. So what do you do? Spend out more money to sort out the fixing or take it back and return it as it's obviously not "fit for purpose"

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Hi Walfy, I guess there must have been some testing/maths involved.

I don't have my old copy of COP 11 handy, but there was an amendment in 2002 which is here:

http://www.lpga.co.uk/CoP%20Amend/COP11%20...0Nov%202002.pdf

If you have a look on pages 2 and 3 of the amendment it shows that the deceleration force requirement was reduced to 20g front to rear and 8g side to side.

The amendment also gives guidance on the number and size of bolts and spreader plates required for different capacity LPG tanks.

In my opinion the guidelines were written on the basis that the tanks would be fitted to steel monocoque vehicle bodyshells.

We should be extra careful with our softer birmabright panels, which is why I would recommend a steel strap from the floor mountings to the chassis as a minimum back up in a defender/series where the tank is just bolted to the floor.

I guess that providing the correct number/size of bolts/straps and spreaders as listed in the guidelines are used, you have to accept the installation, have it crash tested, or come to some sort of agreement with the installer on extra fittings.

One of the reasons I did my own conversion years ago was because I wanted it done in accordance with the guidelines and to my standard of workmanship, and not someone elses.

Hope this helps,

Regards,

Diff

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I don't have my old copy of COP 11 handy, but there was an amendment in 2002 which is here:

http://www.lpga.co.uk/CoP%20Amend/COP11%20...0Nov%202002.pdf

Pertinent bit from the above document:

> For example, for cars and light goods vehicles the tank must be

securely mounted to withstand acceleration of 20 g in the direction

of travel and 8 g horizontally and at right angles to the direction of

travel.

Straps, bolts and spreader plates should be designed bearing in mind the

material, profile and thickness of the mounting panel to ensure an adequate

contact area.

Also saw this bit:

"The fuel tank should be installed so that its lowest point is no lower than the

original load bearing points of the vehicle which are part of the vehicle

structure and so that the original approach, departure and ramp angles

(typically 25o, 20o and 20o) and ground clearances are maintained."

I have seen sill-tanks that are so low that they become inadvertent rock-sliders :huh:

Rog

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Perfect Diff, thanks. I am of the same opinion as yourself. i.e if I am carrying that weight around, I want to make sure that it is attached to my standards, not those of some spotty 17 year old graduate of the Kwik Fit academy!!

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  • 1 month later...

the maths is quite simple: a 20g force just involves weighing [estimating] the full tank, then being sure the mountings are up to 20 times that weight — without needing to test it, there should be reference charts for the breaking/tearing strengths of various thicknesses of ally/steel, bolts, welds, etcetera

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Just checking maths. Assuming that liquid LPG has approx. 0.5 weight/density ratio to water, so 0.5 tonne per cubic metre, then the contents of my full tank (at 80%) would weigh 0.055 of a tonne or 55kg (pye x r squared x length). Allow 25Kg for the tank arrives at around 80Kg - It is a heavy 2 man lift, so I would assume this is about right.

So, Breaking force required 1600Kg (say 2000Kg for safety margin /old metal not in its prime) divided by number of mounts should get me a solid fixing.

Thanks Markie.

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I'd make some straps from flat bar and take them from the tank mounting points (with a hole to bolt through) to the nearest bit of chassis (where they'd be welded).

Cheap, simple and quick.

Mo

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