TT Talk - Don't forget counterfeit refrigerant
It is now approaching two years since safety alerts were raised in connection with reefer containers designed for use with R134a refrigerant which were re-gassed with counterfeit refrigerant. Happily, the TT Club is not aware of more explosions or injuries. There is no reason, however, to be complacent.
During a period of about eight months in 2011 there were five documented reefer compressor explosions, in which three people were killed, and other minor incidents, such as smoking valves or flaming oil. The cause was established to be counterfeit refrigerant, containing a blend of chemicals including R40 (Methyl Chloride). This is a poisonous and reactive chemical and it is understood that methyl chloride combines with aluminium components in the compressor to form volatile chemicals, including Tri Methyl Aluminium (TMA), which burns spontaneously in air and water, and strong acids. It is believed that TMA may have reacted with other chemicals in the system to cause the explosions.
These original incidents appeared to be connected to re-gassing carried out in Vietnam. As a result, US West Coast longshoremen quarantined over 1,000 reefer units. It is estimated that only 2% - 3% of these units are actually dangerous.
Since that time there have been no documented explosions, but counterfeit refrigerant containing methyl chloride has been found in other countries and on board ships. On a reefer container fleet of about 1.3 million units, there are in the region of five million PTIs (Pre-Trip Inspections) per year and counterfeit gas is reported to have been discovered in about 5% of units tested.
Following these incidents, a number of shipping lines and container lessors, and some depots, have implemented testing regimes for reefer machinery. Importantly, many depots have started testing refrigerant gas supplies prior to use. Testing of R134a in both reefer machinery and gas bottle supplies has revealed various contaminants, some not compatible with compressor lubricants or simply inefficient as refrigerants.
"Testing of R134a in both reefer machinery and gas bottle supplies has revealed various contaminants, some not compatible with compressor lubricants or simply inefficient as refrigerants"
It has been somewhat puzzling that reefer machinery that has been found to have been contaminated with gases including R40 has given rise to variable reactions. The chemistry is complex, but there can be little doubt that contamination is potentially dangerous. Regardless of the risk of injury, the refrigeration machinery is generally degraded and will almost certainly not perform properly or for the expected lifetime. Operation with contaminated refrigerant is likely to result in reduced cooling capacity, increased power consumption, inability to maintain consistent temperature control, greater frequency of breakdowns and higher M&R costs.
As would be expected, there are purity standards in use by manufacturers of both refrigerant gases and refrigeration equipment - the most widely adopted is set by
(Air-Conditioning, Heating and Refrigeration Institute). The relevant standard for refrigerant gas source purity, AHRI Standard 700-2012, was updated during 2012. This was followed up in February 2013 when AHRI published a
providing a useful summary of the situation and, particularly sound advice which the TT Club would fully endorse: