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 Post subject: Old LPG tanks
PostPosted: Tue May 22, 2018 3:30 pm 
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I have an old Volvo 850 that has been with me for many years (17+), and still has a fair amount of life left so I don't plan on getting rid of it any time soon. For the last few trips to the filling station, some issue has been severely restricting the gas flow into the tank and causing it to fill up at a snails pace (you can easily count each and every penny as it ticks by on the pumps display).

So faced with the likelihood of having to de-pressurise the tank (4 hole 57l toroidal) and remove valves to diagnose what's causing the problem I was wondering what the situation is with old LPG tanks both from a legal perspective and a 'best practice' side, as if there's something I need to do with a tank this old, now would probably be the best time to do it.

I am aware that domestic LPG tanks and cylinders require re-certification every 10-15 years, but was told that the authorities assumed that cars would be scrapped long before any issues would be likely to occur with automotive tanks, so there are no requirements to have them tested.

So are there any places in the UK (preferably south east) that will test and re-certify an automotive LPG tank? Or is it just a 'keep calm and carry on' situation, and if you're uncomfortable having such an old tank in the back of your car, you simply rip it all out and fit a new one?


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 Post subject: Re: Old LPG tanks
PostPosted: Wed May 23, 2018 7:38 am 
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pinballdave wrote:
Or is it just a 'keep calm and carry on' situation, and if you're uncomfortable having such an old tank in the back of your car, you simply rip it all out and fit a new one?
That's about it. If it was an underslung tank open to the elements and rotting away, then you'd likely want to replace it. That would be an MoT fail too as the test includes the fuel system whether it is petrol, LPG or both. If it's inside the car and you are happy it doesn't have any weaknesses, then leave it. While you are changing the valves it might be worth lifting it and having a look in case it is rotting where you can't normally see it.

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 Post subject: Re: Old LPG tanks
PostPosted: Wed May 23, 2018 9:11 am 
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Yep.

Problem might in any case be the filler on the vehicle, they have a one way valve to prevent gas in the line between the tank and filler escaping when you've disconnected the fill gun, this valve can stick and is more open to elements than tank valves

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 Post subject: Re: Old LPG tanks
PostPosted: Wed May 23, 2018 10:41 am 
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LPGC wrote:
Problem might in any case be the filler on the vehicle,


And this is where I have a dilemma. I know I need to replace the filler and housing, as the lugs on the side of the bayonet fitting are worn, and you get a bit of gas leakage if you nudge the filler gun while filling the tank. Also the plastic housing has cracked and is letting moisture into the rubber boot, so the JIC fitting on the end of the hose is starting to look a little corroded and should also be replaced. So that's a £60+ shopping list for all those bits.

If I fit those and then find the problem is with the fill valve in the tank, do I just swap valves and keep the old tank? If I end up replacing the tank, then the wallet says it'll be a single hole/multivalve which will need an external 8mm fill line and my brand new hose and filler will get binned.

Due to the shape of the boot floor and spare wheel well, there is plenty of room to get a small mirror round the tank and inspect the exterior of it, and it looks immaculate, no traces of rust anywhere. The tank is an open toroid and not filled in the centre so all the weld seams are visible without needing to remove it from the car. So it appears to pass an external visual inspection, I suppose being filled with pressurised fuel all of the time there's very little chance for moisture to get in so they wouldn't tend to rust from the inside, but I've never looked inside a used tank to see if this is the case.


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 Post subject: Re: Old LPG tanks
PostPosted: Wed May 23, 2018 10:50 am 
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You can get a single hole multivalve that takes a JIC hose so you won't have wasted your money on those even if replacing them doesn't cure the problem. If the filler is worn, then I'd replace it and if you have run around without a cap to protect the valve inside it, chances are that is your problem anyway. They don't like being filled up with crud off the road.

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 Post subject: Re: Old LPG tanks
PostPosted: Wed May 23, 2018 12:40 pm 
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Yes again, can buy JIC to copper / Faro adaptors no problem so can use a JIC filler and pipe to run to a multivalve.
The one way fill valve on quite a lot of 4 holes is broken anyway because the installer over-tightens them during fitting, crushing the internals due to the tapered thread. When you come to changing the filler would first have the tank empty or at least slowly slacken the JIC connector at the filler to allow gas to escape and see if it stops escaping before further dismantling.

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 Post subject: Re: Old LPG tanks
PostPosted: Thu May 24, 2018 2:45 pm 
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As it's an old single point mixer system, I managed to run it until the tank really was empty, so there wasn't even a hint of gas escaping when I disconnected the JIC connector at the filler. Swapped the filler and housing over for the new ones, but at that point rain stopped play and I'll need to fit the new hose tomorrow. I feel that this is one job that's best done in a well ventilated outdoor environment rather than in a nice dry garage!

My only concern is the water ingress issue, when it was all dismantled the back of the filler housing and the inside of the rubber boot covering it was quite damp, and the screws and fittings were badly corroded. There doesn't seem to be any waterproofing to the housing to stop any moisture getting in there, and no route for water to drain if it gets in and collects in the rubber boot.

I'm guessing that it's supposed to be like that so the rubber boot seals the connections from the interior of the car, and the gaps in the housing allow any gas leaks to vent outside.


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 Post subject: Re: Old LPG tanks
PostPosted: Thu May 24, 2018 10:41 pm 
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pinballdave wrote:
As it's an old single point mixer system, I managed to run it until the tank really was empty, so there wasn't even a hint of gas escaping when I disconnected the JIC connector at the filler. Swapped the filler and housing over for the new ones, but at that point rain stopped play and I'll need to fit the new hose tomorrow. I feel that this is one job that's best done in a well ventilated outdoor environment rather than in a nice dry garage!

My only concern is the water ingress issue, when it was all dismantled the back of the filler housing and the inside of the rubber boot covering it was quite damp, and the screws and fittings were badly corroded. There doesn't seem to be any waterproofing to the housing to stop any moisture getting in there, and no route for water to drain if it gets in and collects in the rubber boot.

I'm guessing that it's supposed to be like that so the rubber boot seals the connections from the interior of the car, and the gaps in the housing allow any gas leaks to vent outside.


Usually the boot should sit over the back of the filter housing and seal it effectively - It won't seal right next to the bodywork though, if the edges of the hole you have in the body (I can only assume you have it cut through a wing or panel somewhere?) then it may be worth removing any rust thats round the hole and putting some paint on it, then using sealent of some type to seal the edge where the housing goes.

If its been open without a cap though, this will allow more to get in and might in itself be the problem anyway. Suggest you carry on fitting it and keep an eye on it, if its still leaking then you may need to look further into it.


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 Post subject: Re: Old LPG tanks
PostPosted: Fri May 25, 2018 5:22 pm 
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The new filler, housing and hose are fitted, and the tank filled up nice and quick at the pumps. Sprayed a good amount of leak detector around all the tank and filler fittings at the filling station (with the fill hose still attached) and there's no signs of any leaks, so that sounds like it's job done!

I'm still quite surprised that there aren't any formal inspection and testing requirements for automotive LPG tanks.For example, in Australia they need to be inspected and pressure tested after 10 years, and I'd have thought that the LPGA/UKLPG would have insisted on something similar as it would result in more work for their members.

I've also never seen an MOT tester who seems remotely interested in looking at the LPG side, I showed the can of leak detector to the MOT tester last year, as it says that it's suitable for use for MOT tests on the side of the can, he'd never seen it before and said if it doesn't smell like gas is leaking then it gets a pass!


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 Post subject: Re: Old LPG tanks
PostPosted: Fri May 25, 2018 9:33 pm 
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All good then!

Should have added to my last post... The time it takes gas to stop escaping when you slacken filler pipes can be an indicator of whether the one way fill valve on the tank actually works. More likely to work on a multivalve tank than on a 4 hole due to the crush point I mentioned. A test that works better if the tank isn't empty... but a broken one way fill valve at the tank isn't a big deal considering that there's a one way valve on the filler anyway, you weren't doing this to perform such test and you wouldn't want problems during changing the filler - hence earlier advice.

Don't give too much credence to organisations that don't deserve it, LPGA UKLPG can't insist on anything and their supposed safety scheme is farcical but I imagine a good money earner.

MOT man seems to have taken a common sense point of view, doubt he would have failed it if he could smell petrol but implied he might fail it if he could smell LPG. Petrol tanks don't have electronic shut-off valves but LPG tanks do. Due to safety systems built into all aspects of LPG systems they are intrinsically safe, which is something that on the one hand UKLPG would agree with (when promoting the fuel), on the other hand might disagree with (to a lesser degree when trying to promote their vehicle conversion members).

UKLPG seems to have had little to do with MOT changes which now mean MOT man has to look at the LPG system at all. Funnily enough I was the first to say such changes ought to be introduced, first said it on this forum, then it happened...

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