Following on from those thoughts, if wrong sensor fitted, wouldn't shut-off (float at top) be the same, gauge would show empty (float at bottom of its range but not bottom of tank) but you could continue to draw the remaining liquid below that level.
Or is it that when float at bottom it shuts off the gas out valve?
I guess the pickup pipe will also only go part way to bottom of tank too, so it'd start sucking gas, not liquid, when below bottom of pickup pipe?
If I follow on with that logic, if there are no surge baffles in the tank, that would cause the ECU to panic and shut off gas on hard acceleration.
I'm hammering jigsaw pieces together here, rather than putting them together based on actual detail understanding!
Gilbertd wrote:
That's why it won't fill fully then, it's set for a 220mm tank not a 270mm one.
Looking at the design of the float, wouldn't it fill fully, but never empty to the bottom of the tank?
ie- there's half a tank of ullage you're hauling around pointlessly?
Yup, it can't work on pressure as that will be the same whether full or nearly empty and will also vary with temperature. It's all done by the float so if you've got the wrong multivalve, as it appears you have, the float arm will be too short so the range over which it will work will be restricted. It isn't only the float arm that will be wrong but also the pickup tube. So it may well shut at 80% or thereabouts full but not only will the float arm be too short, so will the pickup tube so you'll never fully empty.
There's no baffles in an LPG tank, just a pickup that should go down to the bottom (which is why the pickup should be towards the back of the tank so you've still get liquid when you need it most under acceleration). But if the multivalve is intended for a shallower tank, it doesn't reach the bottom.
Agreed with lines of thinking above, on this design tank and valve it is the pickup pipe length that will make most difference. If the pickup pipe is 40mm too short we would expect 40mm depth of gas to be unusable (at least for purpose of fuelling the engine with a sequential LPG system)... 40mm depth of gas remaining in the tank even when the gauge shows empty and the LPG system seems to have run out of gas.
Yours is a 30degree / internal tank, if this were a zero degree / external tank we'd expect the tank to run dry but fill to be limited to 40mm below the level that it should fill to.
Wouldn't expect the 80% fill to be much affected if yours is 270 tank with 220 valve, just that the bottom bit of tank contents would be unusable... unless someone had extended the pickup tube. On most L322's I've converted I've fitted a 270 height zero degree tank upside down with special upside down Emer valve designed for purpose (and which fits inside a flexible gas tight housing). Emer valves are no longer made so on the last few I've converted I've had to fit an upside down Emer valve made for a 250 height tank, extend the pickup tube and adjust the float a bit.
Lol 40mm, brains not even working out 270-220 tonight it seems ;-)
Thanks Lpgc and Gilbertd for your thoughts and input.
In addition to having (most likely) the wrong valve, it's also installed right at the front of the tank!
In addition to having to drain out the undrainable and fit the correct valve, it now looks like I'm going to have to remount the tank so the valve's at the rear. Good thing that I was intending to replace the main feed line really!
Another 5 minute job that's expanded exponentially.
Lpgc wrote:
Lol 40mm, brains not even working out 270-220 tonight it seems ;-)
That's nothing to me trying to do the maths to work out exactly how much liquid is now ullage- be easy if tank was cylindrical :)
Hehe..
If replacing the lines with Faro you could temporarily fit just the line to the engine making it quite a bit longer at the tank end than you need, and since you'll be shifting the tank anyway you could temporarily stand the tank on it's side valve end down... should allow driving on LPG to get more of the gas out before you take the valve off. Faro ends are all re-usable.
Bit of an aside... Many years ago I converted a limo for a company in Birmingham, I did the engine first and was completing the tank install when I broke the multivalve. The firm needed the car back for the weekend and at the time I didn't have many spares around (certainly not a tank diameter specific mulivalve) so I called around local installers to see who might be able to sell me a suitable valve... A 'done in a day' firm in Leeds who at the time fitted 'Aldesa' gear said I could buy a valve from them, so I went through and bought one from them at a price they'd inflated, and this turned out to be for a second hand valve (could smell gas on it). Still I bought it and fitted it and all seemed well, until the limo firm said they could sniff gas after parking the car up... So I bought another valve on the Monday which arrived on the Tuesday and I went to Birmingham to change the valve, which I found to be leaking from it's PRV, but their limo storage area was under arches in a kind of massive underground limo storage area so I had to take the limo out for a drive by myself around Birmingham to try to find somewhere to vent about 30L of gas. Luckily it was a summer day... so there were no clouds of gas drifting down the hill on the quiet street on a hill I eventually used.
I once vented (er more like released lol) 100L of gas from a cylinder tank in the yard, but first I made sure neighbours etc were out. There was a fair sized stream of very cold liquid LPG running down the yard for about 20 yards, all the tarmac in the area of the stream super chilled, some of the tarmac (in the yard) broke up. Once all the pressure has gone out a tank (because it's got so cold) you can literally pour the gas out, just that whatever the gas then contacts warms it up until the contact has cooled to the same extent.
Ah well, if the Pros do it like that....
:)
This may not concern you much if you run the tank on it's side to use up the bottom bit of gas... One of a valve's seldom mentioned safety features is an excess flow shut off mechanism, if you do vent gas to atmosphere it can be quicker to restrict flow using the thumbwheel to adjust flow of gas coming out to the point just before the excess flow valve activates, particularly if your pickup tube is below gas level. Otherwise if you had say 30L of gas in the tank you could have gas escaping to the point of hearing a strong hiss but get up the next morning only to find it's still hissing to the same extent lol... So then you start undoing the 6 hex bolts cross pattern until you're down to only 2 opposing bolts sealing the valve, which can be a bit of a worry the first time you do it when you know there's still a fair bit of liquid gas and pressure in the tank and the next move will involve breaking the seal... but it's not so much a concern when you've done it a few times. Don't be worried if you need to undo the valve bolts with gas in the tank, if it all seems to be happening too fast etc you can always re-tighten valve bolts, don't be too worried about hissing or cold it isn't that bad. To prevent the car interior stinking you can refit or at least rest the tank valve area cover so most escaping gas goes outside the car rather than inside.
Anyway, your valve might have a pickup tube for a 270 height tank yet, anyway you could probably avoid most of the above running on LPG with tank stood on one side.
Concern me? No, it bloody terrifies me!
Pressure vessels generally give me the heebie jeebies. I must be the only person in the UK who actually takes the inspection panel off of the tank on my workshop compressor twice a year to check the tank!
Fill a pressure vessel with an explosive liquid and I'd rather watch someone else do it, by video link, from another county!
Until I fully understand exactly how stuff like this works, my fear of the unknown will continue.
Can think about it like this.. If diameter of valve opening is only a couple of inches that's only 3.14 square inches, if temp of gas in the tank is only 10c it's at a pressure of only about 75psi, so there will only be about 235 pounds pushing the whole of the valve away from the tank... and recent temp isn't even 10c. Undo the 6 valve bolts slowly and there'll be enough slack on the bolts to provide space between the valve and tank while still fairly evenly balancing the 235 pounds over the 6 bolts... Then it seems not much of an issue.
But you could avoid the above almost completely, either by running the fuel out by sitting the tank on it's side and driving the fuel away or by slowly venting the gas even if the excess flow valve kicks in and slows venting to a very slow rate. If I ever have to do it I slacken the 6 bolts while the tank is venting, I got used to it a long time ago and it doesn't worry me, but it did the first time and I still don't like slackening the last couple of tank bolts even though I know it'll be OK.
If the pressures involved were CNG like then I'd be more concerned but with LPG we're not really talking much pressure
In most cases like the above I've been laid down under a car fitted with a zero degree tank, so liquid gas has escaped after I've removed the valve. Far less concerns on a 30 degree setup where only vapour will escape after slackening a valve, you're not going to get liquid gas squirting out,..A drop of liquid gas hitting your eyeball and cooling it's surface by about 30degC really hurts, this won't happen on a 30 deg setup if the tank is less than half full because only vapour will be expelled
Overalls upgraded. Should be good to go now.
Drive it empty as far as you get, then run a hose to your outdoors propane BBQ and invite all neighbours...
C'mon then, you obviously survived as you've posted on other threads. So how did it go or did you bottle it?
No time today. Repairing stainless exhaust (correctly- couldn't live with the fix I'd already done) on blue one took all my available "my car" time.
Still time to compose my obituary before I tackle the gas tank!
I see the future!
For some reason it seems the forum software doesn't like gifs.
https://i.pinimg.com/originals/01/82/5e/01825e981b49caaa693395ca637376db.gif
and this is the result......
