Talking to ILN yesterday afternoon from the airport, he said crews would meet at the minesite this morning to assemble the GAG unit and complete any minor fabrication work that needed to be done.

The jet engine technology makes an underground mine atmosphere inert by eliminating oxygen through a release of carbon dioxide and water vapour into the mine.

The technology was developed in Poland and was first used in Australia in 1999 to fight a mine fire and create inert mine atmospheres.

Once the GAG unit is ready, the specialist Queensland crews will work with mine management to put in place adequate control measures for its safe operation.

After the risk assessments are done the unit will be used to inert the mine.

“It’s not a large mine so it won’t take a long time but one would expect that they would be looking to inert a couple of times in order to manage the environment,” Hartley said.

He added that it might be too soon for the unit to start up today, which indicates it might be started up on the weekend.

“It would be difficult to speculate because there are a lot of processes to go through and particularly the mine will make that decision when they actually commence operations.”

Hartley estimates it will take between four and six hours to inert the Pike River mine the first time.

Rescuers will be able to enter the mine once the underground environment is completely managed.

Using the GAG would kill any possible survivors still in the mine, but all the missing miners are assumed to have died after the second explosion at the colliery on Wednesday.

The first explosion took place last Friday with only two miners managing to evacuate.

Under the emergency procedures, the miners must walk out of the mine using their self-contained self-rescuers.

There are no safety refuge chambers at Pike River.

New Zealand Prime Minister John Key said the loss of the 29 miners was a national tragedy.

Methane levels remain dangerously high at the mine and yet another explosion could still occur.