SINGAPORE - A 22-year-old Bangladeshi worker servicing an air-con compressor inadvertently caused an explosion when he switched on a vacuum cleaner, creating a spark that ignited flammable gases.

The blast and ensuing fire resulted in his death.

On Tuesday (April 26), his company, Sing Wah Enterprise, was fined $150,000 after it pleaded guilty to a charge of contravening the Workplace Safety and Health Act by failing to take necessary measures to ensure the safety of its workers.

A district court heard that on Aug 15, 2012, the worker, Mr Abadul Jaynal Sikder, and two colleagues went to Toshiba Tec Singapore's premises at 2 Ang Mo Kio Street 2 to convert the refrigerant gas used by two compressors in a cooling unit.

The compressors used an extremely flammable hydrocardon refrigerant gas that the Singapore Civil Defence Force had, one a year earlier, told users to stop using within the next five years as it posed a potential safety hazard.

At about 10am on the day of the accident, Mr Sikder and his colleagues started the refrigerant conversion works in an air handling unit room.

One worker applied a chemical solution to the cooling coils of the cooling unit, and then used a high pressure washer to wash off the chemical solution.

Another discharged the hydrocarbon refrigerant from one of two compressors of the cooling unit near the window in the room. The gas was let out of the room via an open window.

At about 10.15am, Mr Sikder switched on a vacuum cleaner to remove the waste water on the floor, which came from the washing of the cooling coils earlier.

But this created a spark and caused a blast.

The two colleagues escaped though the open window while Mr Sikder went out the room door.

All three suffered burns and were taken to hospital. Mr Sikder died four days later. His cause of death was bronchopneumonia following extensive burns.

During the coroner's inquiry into his death, in April 2013, the court heard that the door to the room had been closed and only one window was open.

The coroner pointed out that according to experts, hydrocarbon gas is denser than air, which means it will sink to the floor.

So an active ventilation system should have been used, the coroner said, as the open windows may not have be enough to ventilate the room.

Ministry of Manpower prosecuting officer Delvinder Singh asked that a fine of $150,000 be imposed on Sing Wah.

He said the company did not have a copy of the safety data sheet of the hydrocarbon refrigerant to be purged. The sheet would have contained instructions for the safe handling and potential hazards of the product.

The prosecutor also noted that the proper method of replacing the refrigerant gas, as stated by the supplier of the cooling unit, is to store the gas in a tank instead of releasing the gas into the air.

"The accused company had failed to conduct a risk assessment and safe work procedures for the hydrocarbon refrigerant conversion works that it was contracted to perform," said Mr Singh.

"Furthermore,the work method that was adopted was wrong as it failed to address the possible accumulation of flammable refrigerant and ignition of the accumulated refrigerant, which eventually caused the explosion and subsequent death of the deceased," he added.

The maximum punishment for a company which contravenes the Workplace Safety and Health Act is a $500,000 fine.