Police say a machine pumping nitrogen gas into the Pike River coal mine, has been operating all night and is working well.
The 20 tonne Floxal nitrogen generator arrived at the mine site near Greymouth on Saturday afternoon.[image:773:half:left]
The machine is pumping the inert gas into the mine in conjunction with a GAG engine, which has been operating for several weeks to put out fires inside the coal pit, and cool down the temperature in the pit.
The aim is to make the mine safe to enter so the remains of the 29 men who died in explosions a month ago can be recovered.
Police say the nitrogen machine began operating at 6.15pm on Saturday.
They're planning to turn off the GAG unit at some stage, to measure what effect the nitrogen gas is having on the environment.
Police say gas samples taken overnight from inside the mine can be described as positive.