Gas sensor failed to alert

The entrance to the Pike River Coal mine.
The entrance to the Pike River Coal mine. Simon Baker - NZ Herald

THE Pike River Mine relied on a gas sensor that was in a "sad state of repair", before the explosion that killed 29 miners including Tinana dad Willie Joynson.

The Royal Commission of Inquiry into the disaster heard yesterday the devastating explosion of November 19, 2010, could have been the result of a collapse in the area already mined, that sent explosive gases racing through the mine.

That may have happened as the water pumps were turned on, re-powering the electrical system, which may have begun sparking and arcing.

Australian David Reece, one of five experts used by the Department of Labour to reach those conclusions, said a gas monitor in a panel had been poisoned by high levels of gas and did not work or had been disconnected.

"For even a moderately gassy mine to rely on one sensor at the top of the shaft, which was difficult to access ... is hard to comprehend."'

The sensor was in a "fairly sad state of repair", he said.

Methane levels measured in the main shaft on November 15 and 17 were 2.75%, but closer to the coalface they would have been at least twice as high.

However, records from those days did not record this.

Mr Reece said it was apparent sensors were not being calibrated and maintained because two that were close together gave different readings.

He said Pike River staff reports and modelling after the disaster showed a "serious lack of ventilation" for the number of coalfaces being worked.

"You could see that deputies at times were having trouble just getting air to move in the direction it should."

Putting the main fan underground and in a high-hazard area was "highly unusual".

The pipeline meant to drain gas could not cope with the volume and was probably blocked.

Mr Reece said he thought the first explosion was probably fairly deep inside the mine.

The two survivors did not recall feeling a heatwave and the temperature at the point of ignition would have been 700 degrees Celsius.

Topics:  explosion miners pike river mine

UPDATE: Wildlife officers investigate after croc drags cow

The Mary River where the crocodile was spotted attacking the cow.

A motorist spotted a cow being dragged into river by a crocodile.

Stay safe near water after croc seen attacking cow

G'DAY MATE: Macca sunning himself at Snakes Down Under before his feeding time. Photo: Mike Knott / NewsMail

A motorist has reported seeing a crocodile attacking a cow

Alison's dream to meet real-life Cinderella comes true

Point Vernon resident Alison Bartlett gets a visit from Cinderella (Leanne Hodges) on her 49th birthday.

Her visit is a fairy-tale ending to Alison's dream.

Local Partners

Kanye West threatens to boycott Grammys

West says he won't go to the Grammys if Frank Ocean's not nominated

Why this actress wasn't embarrassed by nude photo leak

Leslie Jones source Bang

'If you wanna see Leslie Jones naked, just ask,' she said

Dad's Army comic genius Jim Perry dies

Jimmy Perry, the creator of Dad's Army.

Dad's Army series captured all that British people savour

Check out some fashions from the Coast festival

FASHION: Ocean Zen range.

Images from the Sunshine Coast Fashion Festival show what's hot

Australian Survivor's magician Matt out of tricks

Australian Survivor contestant Matt Tarrant.

SHOW'S power couple looks unstoppable in race to the finish.

Top floor teams take out The Block's terrace week

Kim and Chris pictured on their winning outdoor terrace in a scene from The Block.

RIVALS Kim and Chris and Julia and Sasha tie in final week of work.

Hinterland horse stud passed in for $8.25 million

UNREAL: This Maleny estate is incredible.

12-bedroom hinterland horse stud still available

Hit songwriter's Noosa mansion on market

SPECIAL PLACE: The Cintamani estate is going to tender, marketed by Tom Offermann Real Estate.

Is this Queensland's best property?

Kiwi siblings snap up Dotcom mansion for $32.5m

The new toy company owners of the Coatesville mansion want replace any controversy with positivity and fun. Photo / Barfoot and Thompson

The trio paid $32.5 million for the property in June

New $200 million development will create 580 jobs

Cassie And Josh with baby Alfie and daughter Andee. They have bought at new Lennox Head development Epiq.

Majority of new positions will be given to Northern Rivers locals

Cherrabah's mega resort plans axed

PLANS for a massive development at Cherrabah have been scrapped.

What our mayor thinks of the new draft SEQPlan

The plan to use the innovative technology as part of the new Maroochydore CBD was cemented on site today when Mayor Mark Jamieson and Envac Asia Region president Chun Yong Ha formally signed the contract for the $20 million underground waste collection system.

New plan accommodates Sunshine Coast Council's vision for growth.