HONEYWELL and the German testing body BAM has hit back at claims that use of the refrigerant HFO-1234yf in mobile air-conditioning poses a flammability safety risk.
A report, published this month, called 'Determination of the explosion region of ethane-HFO-1234yf -air mixtures', describes tests on the refrigerant by the German Federal Institute for Materials Research and Testing (BAM).

According to the natural refrigerants website BeyondHFCs, the new BAM tests confirm that HFO-1234yf used in mobile air conditioning is 'dangerous'.

Dr. Kai Holtappels, head of the working group at BAM said: 'There has been a misinterpretation by BeyondHFCS of the findings of the test results. BAM does not comment on any hazards posed by the refrigerant 1234yf'.

HFO-1234yf, with a lower flammability limit of 6.5% by volume in air, is described as mildly flammable. By comparison isobutane is 1.6% by volume in air.

In the BAM test, ethane, a highly-flammable hydrocarbon, was mixed with HFO-1234yf. It was found that a 0.5 % to 1.3% concentration of ethane ignites the HFO-1234yf-air composite at 2% concentration of HFO-1234yf.

A spokesman for Honeywell said: 'The amount of ethane added to the mixture was much higher than the typical amount of gaseous hydrocarbons found in an automobile'.

The company added that it did not believe that the test in question was representative of real-world conditions.'

'Numerous tests by leading third-party global experts in automobile safety have been based on typical levels of hydrocarbons present in automobiles, and they have all concluded that the use of HFO-1234yf does not pose a significant flammability risk', added the Honeywell spokesman.

Dr Holtappels added: 'The assessment of the hazards presented by a substance in normal use in technical equipment cannot take place based only on a single individual test series. Various scenarios must be analysed and a holistic hazard analysis performed. Only then it is possible to reliably comment on the dangers posed by the use of such a substance in technical devices. BAM only confirms the execution of leakage tests, it does not comment on any potential hazards arising from the use of the refrigerant 1234yf in cars'.

The US Environment Protection Agency (EPA) has a deadline of February 24, for comments on the subject of allowing the use of HFO-1234yf in ac systems in the US market, under the Significant New Alternative Program (SNAP).