LPG Tank

Message

ynott · #1 Post by **ynott** » Mon Jan 19, 2009 10:41 am

Hi
I have a 84-86 ltr lpg tank fitted to my range rover which i have been told should hold 72ltr of fuel but all it will take is 52lt the garage that fitted the tank has no answer.
Please can you chaps help
Thank You

ttalps2000 · #2 Post by **ttalps2000** » Mon Jan 19, 2009 12:28 pm

do you use the same garage to fill up each time? Most pumps have different cut off pressures! Mine should hold 48 litres, ive only ever got 45 in max from empty!

badger · #3 Post by **badger** » Mon Jan 19, 2009 6:18 pm

Filling quantity has absolutely nothing to do with pump pressure. If the pump produces a pressure higher than the internal pressure within the tank, then liquid will flow, it's that simple. Pressure within the tank remains constant due to the incoming liquid trying to increase the tank pressure, causing the vapour in the tank to liquify. The pressure change within the tank whilst filling is in the order of 3 or 4 psi, temperature dependant.
What is more likely happening, is the float arm on the sender unit is incorrectly set. Manufacturers set them up erring on the side of caution, the net result being a tank that shuts off at a lower than expected volume. The shut-off valve is a plunger that is held against gas pressure by the float arm and released, causing the flow to cease, at a set point. I measure all my float heights when assembling them and tend to find that bending the float up by roughly 1" has the tanks shutting off at exactly the right level in most cases.
Different filling quantities at different gas pumps has, in my opinion, been more down to vehicle attitude (sloping one way or another) than anything else. My landrover fill varies by around 4 litres (checked from empty) with a 5 degree slope left or right. Torroidal tanks are the worst in this respect, closely followed by long, small diameter cylinders. I have, however, came across the odd multivalve that will keep flowing at a much-reduced rate off certain pumps.

ynott · #4 Post by **ynott** » Mon Jan 19, 2009 11:29 pm

Thanks Badger
The garage i fill at has a lot more than 5 degree slope and the last 2 or 3 times i have been empty so first i shall try another garage when empty.
My gauge only has 1 or 2 green after a fill as well does that mean any thing
Thanks

Kiltyhill · #5 Post by **Kiltyhill** » Wed Jan 21, 2009 12:10 am

Hi Badger

Mine is suffering the same, 105 litre torroidal with max possible of 70 litres when filling parked uphill, 62 litres parked down hill, these figures are from completley empty of at least when the system has switched over to petrol. Is it difficult to remove the float and adjust as you have described?

Thanks in advance and sorry Ynott for hijacking your question..

Kiltyhill

badger · #6 Post by **badger** » Wed Jan 21, 2009 3:23 pm

You need to vent the system safely to completely empty the tank. I suggest doing it outside on a windy day with ALL doors and windows open!
Once vented, undo pipes and electrical connections, unbolt multivalve from tank, ease out, bend float arm upwards by roughly 1" and reassemble. When filling, put in roughly 3 or 4 litres and run engine on gas and leak check everything disturbed with a soapy water solution. Once happy with leak check, continue filling and see what it takes, including the initial few litres.

SimonHobson · #7 Post by **SimonHobson** » Wed Jan 21, 2009 6:48 pm

badger wrote:You need to vent the system safely to completely empty the tank.

Yes, that really does mean having the tank completely empty and de-pressurised BEFORE undoing the valve.

Once vented, undo pipes and electrical connections, unbolt multivalve from tank, ease out, bend float arm upwards by roughly 1" and reassemble. When filling, put in roughly 3 or 4 litres and run engine on gas and leak check everything disturbed with a soapy water solution. Once happy with leak check, continue filling and see what it takes, including the initial few litres.

It's trickier on a toroidal as there is a rubber pipe that is supposed to get vapour from the top of the tank if the relief valve lifts. It tends to slip and can make the float arm stick.

On a 4-hole tank, it's different again - the fill valve needs unscrewing from the tank and you need to be careful that the float arm for that doesn't catch on the dip tube or the float for the contents gauge as you do it.

Kiltyhill · #8 Post by **Kiltyhill** » Wed Feb 18, 2009 3:42 pm

Hi Guys

Update on tank fill quantity.

Removed the float and bent as described, now filling 76 litres, definite improvement!!

However! I asked for and was told that I was getting a 105 litre tank but the tank is actuall a 95 litre tank, stamped clearly on the side!!!

I've been conned.

Thanks for your help, mystery solved.

Kiltyhill

whitelion58 · #9 Post by **whitelion58** » Wed Feb 18, 2009 9:11 pm

Hello
I have a similar problem with a system I removed from a scapper and fitted to my Rover. It runs great and all is well, but the 90litre cylinder tank never takes more than 40 litres, which really limits the range.

I guess the most likely cause is the float arm being wrong, but any other possible causes? I suppose the angle I mounted the tank at will have an influence, but it looks similar to other installations. How close to "30 degrees" does it need to be?

Suppose I just have to run it dry and pull the float out as already discussed to be sure.
Tim

Kiltyhill · #10 Post by **Kiltyhill** » Thu Feb 19, 2009 10:25 am

Interestingly when I took my fill float arm out, it had been bent by jamming against the rod for the fill indicator, to prevent that happening as I re-fitted it, I had to remove the fill indicator, fit the fill float then re-fit the indicator. It may be worth checking that.

Best of luck!!

whitelion58 · #11 Post by **whitelion58** » Thu Feb 19, 2009 5:18 pm

Thanks for the reply, will get the spirit level out as soon as I can find some time. Got to fit a second kit to my second Rover in next week or two, so will check it then.
Cheers
Tim