LPG Contamination Has Been an Ongoing Issue

Contaminants in the supply of LPG could cost the supplier, installer and consumer thousands of dollars – are the New Zealand LPG supply standards so inadequate that we are bordering on systemic failure within the industry.

Contaminants in LPG have been an ongoing problem here for a number of years. Both here and in Australia owners of automobiles running on LPG have reported problems arising from contaminated gas.

The Courier in Australia reported in 2008 that “at least 50 cars in Ballarat have undergone LPG tank repairs in the past week after a gas contamination at a Shell outlet. Most of the cars had been found to have a build-up of a wax-type substance in the gas that was causing the valves to stick.”

Joseph Tan posted a message on the Aussie Phorum website “Today while my Commodore VX was in for a routine LPG mixture tune-up here in Adelaide I was told that my converter has once again begun gunking up due to LPG contamination. My LPG/dual fuel conversion took place eight months ago, and this is the second time I've been hit with this contamination issue.”

Here in New Zealand we are having the same problems. We visited an LPG garage to find a technician removing a brown oily substance and wax from the vehicle’s gas converter. He told us this has been an ongoing problem for years. He has reported these issues to the gas supplier but nothing appears to have been done about it.

There have also been problems with the supply of LPG to the domestic household market. According to the LPG Association, approximately seven years ago there were quite a few problems with ‘waxing and oiling’ of gas regulators and systems. An investigation identified contamination of the gas from phthalates extracted from the rubber pigtail hoses connecting bottles to the regulator. Because of this the LPG Association put out a recommendation to suppliers that hoses should have a phthalate content of less than two per cent.

However, since that time system failures continue and at great cost to the industry and public.

In March this year a member of the Auckland Master Plumbers Association (AKMPA) appeared before the small claims tribunal for the cost of repairs to a gas instantaneous water heater, regulator and system failure that was installed by the member in 2007. A “wax’ and yellow oily substance was found in the regulator and water heater components causing them both to fail. The installation had a condensate drip installed at the regulator which was also found to have a yellow oily substance in it.

The cost of repairing the installation was approximately $2400.00. At the hearing the gas supplier, the regulator supplier, the water heater supplier and the gasfitter agreed to pay a quarter of the repair bill each thus saving any financial burden to the customer. In April the same member installed another LPG system supplying an instantaneous water heater, hob and fireplace. Within 6 weeks the system failed. On inspection the the regulator had “waxed” and failed and the condesate drip was full of yellow liquid. The regulator was replaced and the installation checked for operation.

The Member approached the AKMPA for help regarding the contamination problem and what could be done.

AKMPA agreed to help the member because this problem affects not only its members, but the whole industry as well as the public of New Zealand.

The regulator installed on the original installation (orange regulator) and the regulator and hoses installed on the second installation (blue regulator) were taken to Chemical Consultants (Consultants) for analysis.

They extracted a yellow oily substance from the condensate drip of the orange regulator. The infrared spectrum of the oil was recorded and found to be consistent with a diakyl phthalate ester, and probably di-i-octyl phthalate.

The Consultants have stated the chemical is widely used as a plasticizer to impart flexibility to many polymers, paints and rubbers and would have been dissolved out of such a material by the LPG. On conversion of the LPG to its gas state, the plasticizer has been left as a residue on the interior of the components in the regulator.

The blue regulator & pigtail hoses were then examined by the Consultants. They extracted a small amount of oil from inside the ball valve attached to the regulator and found the extract consistent with dialkyl phthalate ester and probably di-i-octyl phthalate.

They also opened up the regulator to examine its internal workings. They did not find any oily substances but did find a white powdery solid adhering to the blue housing and to the rubber seal.

Interestingly, they found the solid consistent with a mixture of a phthalate ester and a hydrocarbon wax. The waxy portion of the solid may either be residual from the LPG gas, or may be extracted from rubber components in the system.

The black flange of the regulator was also tested and found to have 5.1% phthalates, well in excess of the 2% maximum recommended by the LPG Association.

Further to the above report AKMPA had the Consultants determine if there is a phthalate plasticizer in the pigtail hose connecting the blue regulator. The external woven steel casing was removed and they determined the amount of hexane-soluble matter in the sample as a whole. As hexane is a hydrocarbon its effect simulates that of LPG on the rubber. They recovered 7.1% extractable matter, and infrared analysis showed the extracted material to be consistent with a phthalate ester, probably DIOP, the material found in the condensate drip of the orange regulator.

They then ascertained whether phthalates were being extracted by the passage of LPG through the hose

Inner Surface Outer surface Recovered Extract 3.7% 9.1%

They noted the rubber appeared to be a homogeneous material when looked at under a microscope, so it appears that there has been extraction and removal of plasticizer from the rubber hose, and this is a likely source of the phthalate plasticizer residue found in the regulator examined earlier. In accordance with the determination put out by the LPG Association the hoses should have contained less than 2% phthalate plasticizer –these hosed contained more that 9%.

The Consultants also noted that other hoses or polymeric compounds further upstream in the delivery of the LPG may also be potential sources, as the plasticizer will only be deposited on evaporation of the LPG.

Yet importers and plumbing suppliers are still selling these products that are not fit for purpose even though they meet the standard.

AKMPA are asking all members to please let us know of any problems you may have or have had.

We also ask that suppliers ensure the hoses and regulator diaphragms do not contain more that 2% phthalates and warn members that you have a responsibility to the consumer that the products you sell are fit for purpose.

Next month – is LPG gas already contaminated before it is delivered to the consumer?