Coolstore inquest: gas leak before explosion

The blaze was one of New Zealands biggest. Photo / Herald on Sunday

An inquest into an explosion at a Waikato coolstore that killed a senior firefighter and injured several of his colleagues has heard how the plant had ongoing problems - including a major gas leak - just months before the fatal blast.

The coronial inquest being held at the High Court at Hamilton comes more than three years after the explosion at the Icepak coolstore killed Derek Lovell and wounded several of his colleagues who were investigating an alarm activation on April 5, 2008.

In his evidence, Department of Labour health and safety inspector Keith Stewart highlighted a number of deficiencies at the plant including gas detection systems and alarm activations that did not work.

The inquest heard how the plant's refrigeration system was installed by Mobile Refrigeration Specialists but it was prone to leaks and needed constant maintenance.

MRS invoiced Icepak to replace more than 200kg of hydrocarbon gas, hychill minus 50, on 15 occasions although neither the Department of Labour, the Waikato District Council nor the Fire Service were aware of its use at the coolstore.

In November 2007 there was a major leak in plant room at the coolstore with 80kg of the gas leaking out.

On the day of the explosion, Mr Stewart said a ruptured pipe leaked the gas into the plant but Icepak's gas detection and ventilation systems were inadequate for the type of refrigerant used and failed to pick up its presence.

The failure "rendered all other safety systems inoperative".

He said hycill minus 50, which is 95 per cent propane, is heavier than air and a smoke alarm on the ceiling did not detect it until about four hours after it leaked.

The inquest is set down before Coroner Peter Ryan for another four days.