In June 2014 a qualified diesel mechanic, 39, died from burns and blunt force trauma when a refrigeration compressor blew up during his work. He and another gentleman, a boilermaker by trade who worked as a welder offered to move the refrigeration compressor from the cellar in order to assist. While they were in the cellar working on removal of the refrigeration compressor, a gas explosion occurred in the cellar causing injuries to both of them and resulting in their deaths. As no one else was in the cellar at the time of the explosion, how the explosion occurred is to be gleaned from circumstantial evidence and from the evidence of forensic and other experts set out in some detail below.
For the deceased, anatomical findings included blast injuries of lung (contusions, lacerations and parenchymal haemorrhage); left pneumothorax; bilateral haemothoraces; mediastinal emphysema; 40-50% total body surface area partial thickness bums; less than 1 % total body surface area full thickness burns and inhalational injury (tracheal and bronchial mucosa! erythema and oedema, burns to nose , mouth and face); anterior pericardia! contusion and no significant natural disease.
The compressor at the center of this investigation was located in the cellar which was approximately five meters square. While the cellar had no windows, it had cellar doors which led to the laneway, and could also be accessed via stairs from the ground level bar of the hotel. The compressor was a multi-appliance unit that operated the cool room, the bottle fridge in the bar and the glass chiller.
Prior to the family taking over management of the hotel, the compressor, and other plant had been serviced in 2009-2010 by a Refrigeration & Electrical Service contractor. The refrigerant added by the contractor was SP34M which is described as a non-flammable non-toxic gas containing greater than 95% 1,1,1,2-tetrafluoroethane, less than 1.95% propane, less than 1.95% butane and other ingredients determined to be non-hazardous making up the balance. At the inquest, the contractor testified that this was the same type of non-flammable refrigerant as SP34E except that the latter contained ethane whereas SP34M contained methane.
Since the family took over the running of the hotel, the compressor had been serviced by a different Refrigeration Contractor on two occasions, most recently on 26 June 2012. The owner of the service was a qualified refrigeration and air conditioning mechanic who ran his own business and had almost 40 years’ experience in the industry. According to Mr him, on 26 June 2012, he replaced a faulty TX evaporator valve in the keg cool room, replaced the liquid line filter and added gas to refill the refrigeration system. His evidence was that while it is best practice to bleed a system entirely so as not to create a “shanty” of gases within, it was not uncommon to top up a leaking system, particularly where cost was an issue and this was the preference of the client.
He found no existing label or other information to indicate which refrigerant gas within the compressor before he tended to it. He chose the refrigerant SP34E to “top up” the system on this occasion and attached a label to the unit in accordance with his normal practice to advise others working on the compressor in the future of its contents. In choosing SP34E, he was guided by the setting of the TX valve which is suited to a particular refrigerant or refrigerants and will not work properly with incompatible refrigerants. The setting of the TX valve indicated to him that one of three refrigerants could be used – R12, a gas being phased out in the industry; R134A a replacement for R12 that requires an oil change from a mineral to an ester (or synthetic) oil and is therefore a more costly exercise; and SP34E a “drop-in” replacement compatible with both mineral and ester oils and the therefore the cheaper option in this instance.
He testified that he would never use a flammable gas to top up a leaking system and did not believe that SP34E was flammable. However, he would not like to test this in a confined space such as a cellar, where the leaking gas which is heavier than air would sit or pool and might be ignited. In the absence of pooling and an ignition source, he believed that the SP34E contained gases that posed a risk of asphyxiation, rather than flammability. The compressor needed attention again in October to November 2013 when it was ‘icing up’ and the hotel owner turned to the now deceased who was residing in the residential part of the hotel. The owner knew that, as a motor mechanic, the now deceased worked with motor vehicle refrigerants and, without turning his mind to whether or not he was formally qualified to do so, thought that the fixing the compressor was an analogous task. According to the owner, the now deceased was a skilled man and who was always willing to help out.
Apart from knowing that he used refrigerant gas that came in canisters he had brought home from work, the owner was not aware of the gas used by the now deceased on this occasion. He did say that whatever he did rectified the fault and the compressor stopped icing up.
CAUSE OF THE EXPLOSION: PREPARING TO REMOVE THE COMPRESSOR Observations of the scene after the explosion, indicated a quantity of hand tools to the north and west of the cellar, including spanners, pliers, shifters, a hacksaw and a can of lubricant. There were copper pipes going up the wall and traveling east under the floor plus pipes going to the south and up the wall as well. Three copper pipes on the compressor had been cut and two of the pipes had been bent to crimp the line and two of the other cut ends had been crimped. The cuts to the copper piping appeared to have been relatively new.
In the circumstances, it is reasonable to infer that these cuts were made by either of the men in preparation for removal of the compressor.
CAUSE OF THE EXPLOSION: THE GASES IN THE CELLAR & THE IGNITION SOURCE
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