Auto LPG Gas Tank Ruptures

Submitted: Thursday, Jun 14, 2012 at 16:42

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the nugget

Hi all,
Just to alert those that may have lpg gas tanks fitted;

Saturday 9th of June up near Karratha, a series 100 Land Cruiser had a cold gas tank rupture. The vehicle had twin lpg gas tanks fitted, one being under the LH passenger seat. This tank ruptured causing some serious damage to the vehicle, the passenger excaped with slight cuts and bruise one cut on his forehead.
Information below from a reliable source as to what could have caused the tank to rupture.

Approximately 6-7 years ago it became evident that one specific safety relief valve had been installed incorrectly in a series of new auto lpg containers causing the safety valve to remain closed well in excess of the designed relief pressure. This created a National recall and inspection program to replace any of these valves in service. In WA the Dept of Transport required vehicles licensed as dual fuel with lpg be inspected, rectified if fitted with that particualr valve and signed off by a licensed autogas fitter prior to being relicensed. Some of these valves were also installed by lpg tank retest stations when recertifying tanks. There were a small number of multiple lpg tank vehicles (all petrol that I am aware of) that when fitted using a common fill point and one lpg tank being isolated as a "reserve tank" and after many fills of the main tank the "reserve tank" filled well beyond the 80% maximum and when a faulty relief valve would not open the tank would "cold rupture" due to the lpg expanding in hotter ambient conditions. The volume of liquid inside is too big for the capacity of the cylinder, pressure relief valve fails to open and the tank cold ruptures

http://www.rta.nsw.gov.au/registration/downloads/vib65_19_march_07.pdf

This NSW site has the relevant information and some photos of the Sidek PRX valve that must be replaced. All other relief valves are not affected and larger capacity tanks with 1" BSPT relief valves are not affected either.

Any licensed Autogas fitter (not domestic) can inspect and identify the suspect valve. The best port of call to have it changed if required is a tank test station. They have the facility to decant remaining lpg from the vehicle tank.

Cheers, Nugget.

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Reply By: Ron N - Thursday, Jun 14, 2012 at 19:33

Thursday, Jun 14, 2012 at 19:33

Nugget, this problem has been widely advertised for a lengthy period of time, with large notices advertising the affected range of tanks and valves, displayed at LPG service station pumps in W.A. I'm not sure if it was done in other States.

There is another current issue with flexible fill and delivery hoses in LPG installations, providing a source of problems.

In essence, the flexible LPG hoses used in the last few years have been unable to withstand the extreme solvent action of the liquid LPG, and the LPG has been stripping chemicals known as plasticisers from the linings of the hoses - and dumping the oily residue into the LPG converter/vaporiser diaphragms as well as other components of the LPG system.

Most flexible hoses fitted to LP systems in the last 10 or so years are affected.
The stripping of the plasticiser from the flexible hoses results in a buildup of the oily plasticiser chemicals in the converter/vaporiser diaphragm - which damages the rubber in the diaphragm, leading to failure of the diaphragm, as well as other rubber components.

The failure of the rubber components in the converter/vaporiser has led to backfiring and stalling, that has damaged and even destroyed airboxes, and even damaged bonnets.

http://www.commerce.wa.gov.au/EnergySafety/Content/Regulation/Gas_installations/LPG-Autogas_users_important_up.html

There has been no recall issued for the hose plasticiser problem - but it is recommended that hoses in the LPG fill and delivery systems be replaced with copper or stainless steel piping - and with new, low-plasticiser-content flexible hoses, where flexibility is required.

There is a prohibition order in place since July 2008 that bans the use of flexible LPG hoses with high plasticiser content.
Flexible hoses approved for LPG use since July 2008 must have a low plasticiser content, that limits plasticiser leaching volume to a total of 25mg for any LPG system.

Any hoses carrying vaporised LPG are not a problem. The problem stems from liquid LPG in constant contact with the lining of the flexible hoses, between filler and tank, and between the tank and the converter/vaporiser.

Cheers - Ron.

AnswerID: 488465