Hi guys my car has a 76 litre tank, I filled it last night from nearly empty and managed to get 69.78 litres in. The filler automatically cut off suddenly at 60 litres but after resetting I was able to get 9.78 litres in.

I understand that tanks should not really be filled more than 80% but my question is why was I able to get 69.78 litres in once the cut off valve had stopped filling at 60 litres?

What also concerns me is that on most occasions I refill when there is still probably 25%+ gas in the tank and I can get well over 50 litres in before it's full. I'm guessing on these occasions I have also been brimming it past the 80% limit?

What are the real life risks of filling the tank to 92% of the tank capacity? 2004 Range Rover Vogue 4.4 v8 LPG, Java Black, 22' Hawke Alloys, Black Beast

In the tank there is a little floater similar to the old tank floaters in petrol tanks. The floater is connected to the shut-off valve. Yours is clearly not working properly and I suggest that you get it replaced soon.

I have a major issue with this valve when it got stuck and also one of the filling hoses (hose less than 1 year old) was leaking at the same time. This triggered a police and fire department call out, tow truck and sitting on an abandoned navy airfield for 4 days for the 60 liter tank to vent completely. Luckily the full 120 liter tanks (yes 2 of them) were OK and stayed full.

The big wall on the third picture is to protect the area outside against blast from the navy air planes and they also used to load ammunition in this area.

As ebajema says the filling is controlled by a float on the inlet, in the UK we have a limit of 80% fill, this is never exact and does vary a lot, the reason for this is that it leaves 20% for expansion due to heat, if you filled the tank full (100%) on a cold morning and then left the car parked in the sun all day (with an internal tank) the LPG would expand and want to escape, all LPG tanks have pressure relief valves and this would open and vent the gas, that's why the tank fittings are in a sealed container that vents to the outside of the vehicle...

Most countries have a 90% fill maximum, so getting some extra in won't make much difference, I've got a 92ltr tank and regularly get 79ltrs in it and have never had it vent.

The fill valves come from the manufacturer pre bent to around the 80% mark, if you are worried about it it is easy to remove and bend the float to reduce the capacity but it is trial and error, I'd get an approved installer to do it for you.

I've also found over the years that temperature and pressure of the delivery pump effects how much you can get it so if the station has just had a delivery and it's tanks are full then you will get a bit more in...

If you ever do smell gas in the car, remember that LPG is heavier than air and will sit in the spare wheel well and in the footwells, so open all the doors to let it dissipate... Pete
I now have permission from the boss to use Y.O.L.O. Enjoy life
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Are you sure it's a 76L tank and not a 95L?

80% of 95 is 76.


Cheers





Clive

It's definitely a 76 litre tank as I have all the LPG installation paperwork with the car. I think the previous owner went for the 76 litre tank as it allows the spare wheel shelf to sit flat/flush wheras the larger tank means it doesn't sit completely flat.

The system does cut off at 60 litres when filling which I assume is the 80% cut off, just a bit suprised that after cutting out I am then able to add 9 further litres. To be honest as the car is used mainly locally I will not fill more than 60 litres again but if I'm going on a long run then those extra 10 litres will give me a welcome increased travel range so it's no bad thing as long is it's safe. 2004 Range Rover Vogue 4.4 v8 LPG, Java Black, 22' Hawke Alloys, Black Beast

I would still suggest to replace the floater/shut-off valve because it shouldn't do this. If the tank gets over pressurized the safety valve will vent it and dump it into the grey fittings box and via a rubber hose outside (underneath) the car. You'd smell a problem immediately (that is how I found out about my issue with the GMC).

Better be safe than sorry, range is nice but safety is better.

The cost of replacing the valve was peanuts for me so I assume the same would apply to your car. MY 2010 5.0 SC Galway green and sand interior!!
Have the Faultmate MSV2 Extreme to be tinkering with the settings etc. !!

OK, having driven gas tankers for a few years I'll tell you that the 20% ullage space is a massive safety margin. The tanks themselves can handle way more pressure than LPG could ever exert even in the hottest conditions. It was originally designed for bottled gas which has no PRV and can be left out in direct sunlight for weeks on end.

Consider also that the tank isn't exactly out in the sun in a FFRR, it's usually buried in the boot floor so therefore only ever subject to the ambient temperature, not the extremes of direct sunlight. Possibly more of an issue in Saudi Arabia than Europe.

Then you have the matter of the safety valve venting outside the car so it can never poison the occupants, and given the percentage of gas to air required for ignition the chances of explosion from venting to atmosphere are as good as zero.

I have seen LPG tanks with the fill stop removed but when you consider that you are almost never going to ram it 100% full and leave it in desert heat it's not an issue. How many people live 100 yards from their LPG fill point? As soon as you drive off the forecourt you're creating space in the tank. I wouldn't condone it personally but I know of several instances of it being done and none of them have gone bang, but we're back to the PRV being there to prevent that anyway.

Plenty of people have a distorted view of the dangers of LPG, it's massively safer than they would have you believe. It's certainly a lot safer than a single-skin petrol tank on an off road car. Petrol is a lot more volatile. I think that the worst I ever saw when I was driving tankers was a gas burn from escaping gas which freezes the skin and causes a cold burn. Now that's very nasty, kind of like extreme sunburn.

On the GMC I also reduced the fill percentage to approx. 95% because the tanks were deep down covered etc. And with a GMC, you reduce the volume in the tank quite quickly to say the least . The 2 tanks of 120 liter were installed new and the installer set them "tight". MY 2010 5.0 SC Galway green and sand interior!!
Have the Faultmate MSV2 Extreme to be tinkering with the settings etc. !!

mzplcg wrote:

OK, having driven gas tankers for a few years I'll tell you that the 20% ullage space is a massive safety margin. The tanks themselves can handle way more pressure than LPG could ever exert even in the hottest conditions. It was originally designed for bottled gas which has no PRV and can be left out in direct sunlight for weeks on end.

Consider also that the tank isn't exactly out in the sun in a FFRR, it's usually buried in the boot floor so therefore only ever subject to the ambient temperature, not the extremes of direct sunlight. Possibly more of an issue in Saudi Arabia than Europe.

Then you have the matter of the safety valve venting outside the car so it can never poison the occupants, and given the percentage of gas to air required for ignition the chances of explosion from venting to atmosphere are as good as zero.

I have seen LPG tanks with the fill stop removed but when you consider that you are almost never going to ram it 100% full and leave it in desert heat it's not an issue. How many people live 100 yards from

their LPG fill point? As soon as you drive off the forecourt you're creating space in the tank. I wouldn't condone it personally but I know of several instances of it being done and none of them have gone bang, but we're back to the PRV being there to prevent that anyway.

Plenty of people have a distorted view of the dangers of LPG, it's massively safer than they would have you believe. It's certainly a lot safer than a single-skin petrol tank on an off road car. Petrol is a lot more volatile. I think that the worst I ever saw when I was driving tankers was a gas burn from escaping gas which freezes the skin and causes a cold burn. Now that's very nasty, kind of like extreme sunburn.