Solenoid isolation valve requirements and tank connection help please?

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TVS
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Solenoid isolation valve requirements and tank connection help please?

#1 Post by TVS » Fri Feb 22, 2019 10:00 pm

Just joined this board having found the really helpful articles at http://www.diy-lpg.co.uk and followed the links back. I’m doing a DIY conversion on an old Rover 25 as my commuting car. I’ve got a 1200l tank at home which has saved me a lot of money when filling up our 3.9l Discovery - I think the LPG works out at around 52p/litre with VAT and UK duty. The Disco was converted before I bought it so I’ve now got a few questions about the conversion on the Rover if I may…

I believe CoP11 states that a solenoid valve must be fitted to cut-off the gas supply if the engine isn’t running. Does this need to be a completely separate system from my LPG ECU please? I’ve bought an Optima Expert with the OBD live fuel trim compensation and the installation diagram shows this solenoid valve wired directly in parallel with the solenoid valve on the reducer. Is this OK please?

I’m fitting a donut tank to fit in the spare wheel well in the boot. The rear bumper doesn’t seem to lend itself very well to fitting the LPG filling point but there is a good point on the rear wing on the opposite side to the petrol filler. However this would mean the back of the filler is inside the boot and I’m aware that the connection and pipe would need to be sealed and vented to the outside of the car. To do this I see I can get a rubber boot to fit over the filler point and I believe I would need to run the 8mm copper (rubber coated) pipe through a 30mm ID vent pipe down and through the boot floor? The pipe would then have to run to the middle of the spare wheel well and then pop back up into the middle of the tank for connection to the multivalve. If I run this pipe, and the 6mm feed and tank wiring, though the vent stub from the middle of the donut tank, how much ‘flow area’ do I need to keep please for potential vent flow? Is it the equivalent of 30mm ID i.e. do I need a bigger vent stub pipe than 30mm ID?

One more if I can… these two pipes that would run from the middle of the spare wheel well under the boot floor, they wouldn’t be very well protected. The well is quite low, not quite the lowest point, but not far off – but I wouldn’t run brake pipes here! Is this normal for a donut tank install please? I’m thinking about using a length of steel angle, to replace the washers to hold the tank down, and run one end of this right over to the edge of the wheel well. I can then P-clip the pipes to this angle which will protect them to where I can tuck them up out of the way (with more P-clips etc.). Does this sound reasonable please?

I would really appreciate any pointers with the above. I had to get the Disco certified as it wasn’t on the register when I bought it and the place I took it to kept the ‘requirements’ it had to meet very much to themselves!
Toby

Gilbertd
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Re: Solenoid isolation valve requirements and tank connection help please?

#2 Post by Gilbertd » Fri Feb 22, 2019 10:36 pm

The solenoid valve that must cut off is the two you already have, the one at the tank outlet and the one at the reducer. These are both controlled by teh LPG ECU anyway which detects whether the engine is turning or not so automatically shuts them off if the engine isn't turning. Anything else you hang off the trigger wire isn't relevant.

You've got it for the filler. Yes, the back of the filler point is covered with a boot with a vent pipe attached with the fill line run through that. CoP11 also contradicts itself a little as it says that the pipework should be protected from being damaged (so logic would say that you put a shield over it) but it should be visible along it's length (so you can't put a shield over it). Regarding the vent tube with pipes and wiring running through it, you need to do some sums as it also says:

The vent system should have a free ventilation cross-sectional area of not les than 450 mm2. Vent tubes should, wherever practicable, fall throughout their length.
> Care should be taken to ensure that feed pipes, wiring etc routed through
vent systems do not reduce their free ventilation area below that required (e.g. typical 26 mm vent tubing has an area of 531 mm2, running a coated 10 mm copper fuel pipe (area 95 mm2) through this reduces the effective area to below that permitted.
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Brian_H
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Re: Solenoid isolation valve requirements and tank connection help please?

#3 Post by Brian_H » Fri Feb 22, 2019 11:40 pm

Do you already have the tank? If not, and your putting it into the spare wheel well, then a 0 degree one with the valve on the outside edge will give you more capacity, and allow you to have the valve work and pipework outside the car (by drilling a hole for the multivalve through the spare wheel well so the valve is outside of the well).

Will depend how much space you have to play with, but thats the way the one on my Focus is. The pipework then isn't on the bottom of the tank either as it will come out the side, much easier to protect, and no messing around with vent pipes etc.

The certification now is done via a website - https://www.drivelpg.co.uk/ It can be worth asking around on that front to get an idea where is best to take it, some places will be more amenable to being given an install to inspect than others.

If any of that doesn't make sense, reply back and I can post a couple of photos under mine to give a better idea of what I mean.

TVS
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Re: Solenoid isolation valve requirements and tank connection help please?

#4 Post by TVS » Sat Feb 23, 2019 9:05 pm

Thanks for help, it’s really appreciated! I spent a few hours today looking at the pipe runs (think I now have a plan) and looking to fit the LPG injectors onto the inlet manifold. I got two off 2-injector ‘modules’, rather than the standard 4-injector module in the kit, so with care I can get all the injector pipes exactly the same length and as short as I can (approximately 100mm).

So just to confirm if I may, the solenoid valve on the multivalve and the one on the reducer are all that is needed? I think my Disco has another one between these two but it’s a while since I was under there – I had to fit a shuttle valve for the two tanks as, apparently, once could back-fill into the other.

Yes I have bought the tank, I also did look at the ones with valves on the outside and one of these might well have been easier in retrospect! I was put off at the time as I though the valve might be too close to the boot floor when the ‘more obvious’ solution was to go for the 30deg centre type… It’s a 630 diam x 300 deep which gives a volume of around 75litres. I’m not sure of the size of the tanks on the Disco, but I think both together are only about this.

Bit of a moot point but doesn’t running the fill pipe inside the vent tube does give some restraint issues? For me it looks like it might be about a 1000mm in length with the mandatory P-clips at suitable points, but these aren’t going to stop the copper pipe potentially wobbling around unrestrained inside the vent pipe. I’ve seen “polypipe” is also available, I might be over-engineering this but this would eliminate fatigue…

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Re: Solenoid isolation valve requirements and tank connection help please?

#5 Post by Brian_H » Sat Feb 23, 2019 10:52 pm

The polypipe is much easier to work with than the copper and gives you a bit more internal space. There is nothing you can do to restrain the pipe inside the vent pipe, but you can secure the vent pipe as you say.

Your Disco with multiple tanks would have a solenoid on each tank as well as the one up the front. It might have one between the front and back, though I can't see a good reason you'd want that personally. The typical ones to go underslung on a Disco are around 40 litres each from when i looked so would be about the same capacity. I've got a 160 cylinder in the boot of mine as it just didn't seem like any of the other options would give enough capacity, trouble is that takes up most of the boot space. The non-return valve sounds about right, they can supposedly fill from the other tank under certain conditions so its best to have it. Either way as long as each tank has a shut off, and the vapouriser you should be fine (there may also be a manual shutoff on the multivalve with single hole tanks).

TVS
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Re: Solenoid isolation valve requirements and tank connection help please?

#6 Post by TVS » Sun Feb 24, 2019 7:56 pm

I've found the initial 'fail sheet' for the Discovery and I see they made a note against "electrically operated shut off valve not fitted to the tank" that one isn't, but an in-line valve is and it’s close to the tank so it’s an advisory. This must be the one I've been thinking about. Good to know another isn’t needed!

I modified the original brackets under the car today to also take a P-clip. The reducer is now also mounted securely on the N/S inner wing. Am I OK running polypipe from the multivalve to a joint just in front of the petro tank then with rubber coated copper from this joint up to the reducer? The polypipe I suspect will be a lot easier to fit onto the multivalve valve in the confined space of the tank centre and also route its way past the fuel tank and rear suspension.

On the Discovery front, I've got a pair of cylinders to replace the original fuel tank under the boot floor to fit at some point along with a little second-hand rear wing fuel tank. Unfortunately this is quite rusty inside and so is yet another job to do. I'll also fit new sill tanks at the same time (don't know how old they are but they are defiantly not nearly new!) so should also have about 160 litres total. The range is terrible at the moment - each time we go away in it I have to plan each fuel stop along the way!

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Re: Solenoid isolation valve requirements and tank connection help please?

#7 Post by Brian_H » Sun Feb 24, 2019 11:32 pm

If you need to join it yes, but otherwise you'd just fit one of the ends into the reducer, and the other to the multivalve, then attach the polypipe to that. Is there a reason for using copper for half the run?

You need to keep it away from the exhaust, even if its copper rather than poly. I think 30cm without any sort of shielding is the gap your looking for, but there are options for heat reflection if your running closer than you'd like to.

The solenoid might be down to the age of the tank I guess, but usually they are fitted on the exit from the tank, either directly in the outlet if its a 4-hole or on the multivalve on a single hole.

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