Gas cylinder leak may have caused blast
An explosion in Invercargill that left one man seriously injured was probably caused by a leaking acetylene gas cylinder that came into contact with an ignition source.
Downer employee Dave Evans remains in Southland Hospital in a serious but stable condition with head and abdominal injuries.
Mr Evans was one of two people injured when an acetylene gas cylinder exploded on the back of a Downer ute parked outside Southern Brakes and Driveline in Clyde St about 3pm on Monday.
Fire Service acting assistant area commander Neil Ladbrook said it was believed a leaking cylinder had come into contact with an ignition source.
Several bystanders had described a smell of gas before the explosion.
When the back door of the ute was opened the explosion occurred, Mr Ladbrook said.
Whether a mechanical or electrical spark was discharged or some other outside ignition source was responsible for the explosion was being investigated.
Mr Ladbrook said information from BOC gases indicated that the cylinder had been filled up earlier in the day.
The explosion was felt at the fire station in Jed St, he said.
However, fire investigator Mike Cahill said the cause of the explosion was "still up in the air".
It was hoped that more information would be provided by Mr Evans, who was recovering slowly, he said.
WorkSafe New Zealand was investigating the cause of the explosion.
The Australia New Zealand Industrial Gas Association website says acetylene is very easy to ignite.
A static spark is sufficient to ignite acetylene, a safety sheet on acetylene use says.
The static charge developed by walking across a carpeted floor on a dry day can be 1000 times greater than that needed to ignite acetylene,
The safety sheet also lists an example of an acetylene gas bottle exploding because of static from opening a car door.
Acetylene is the most common gas used for fuelling cutting torches in both general industry and the mining industry.
Southern Brakes and Driveline staff member Mike Larsen said Mr Evans had just left the store when the explosion took place and a huge fireball filled the outside area of the premises.
After turning his head to avoid a face full of glass, Mr Larsen said he and business owner Luke Nicol went to Mr Evans' aid.
"He was moving but in a bad way with burns on his body," Mr Larsen said.
Two women nearby told him there had been a strong smell of gas before the explosion.
Downer Otago Southland general manager Mike Costelloe headed to Invercargill yesterday and confirmed the man injured was a Downer employee, but did not want to comment about the incident.
The Southland Times