Chlorine was one of the gases in the gas cages, contained in the tall cylinders. It was kept in the cage labelled toxic and corrosive. There were gas sensors in every cage because all the gases were harmful in one way or another, some in a combination of ways. Carbon monoxide, for example, was kept in the flammables gas cages, although it is also toxic.
In the toxic and corrosive gas cage, one of the sensors had been isolated because it had been giving false readings and would raise the alarm unnecessarily. It needed to be replaced, and would be replaced as routine, with the other sensors on the annual visit of the manufacturer’s engineer. Only the sensing cell had to be swapped. A tiny red light signified that it was out of service. The cells were replaced routinely, but it wasn’t unusual for one to expire before it was due to be replaced. The plant engineer, Mike, was in charge of this cycle of work. Mike knew gases inside out.
On the other hand, when Dan carried out inductions and trained new starters, he would make a point of reminding people that Chlorine was one of the gases used in the First World War. It would be released when the atmospheric weather conditions were such that a gas cloud would drift over no man’s land to the enemy trenches. Being corrosive, chlorine loves membranes, the delicate surfaces of inner skins. To accidentally take a breath, allows it to eat the airways, burning through the nasal passages, the windpipe, reaching deep into the lungs
Tara only needed to make one measurement. It was late in the afternoon. She thought the line had been depressurised. The cylinder was not properly connected to the manifold and when she opened the valve chlorine was released at full pressure, some 3000psi. Automatically she twisted the valve shut, but the cylinder had ejected a cloud into her face and she screamed and screamed. The thick walls of the cage didn’t heed her. And there was no one outside to hear her.
Fortunately, the chlorine wafted to an adjoining cage and triggered a hydrogen chloride (HCl) sensor, setting off the alarms. Tara had collapsed onto the concrete floor and convulsed, trying to retch at the pain which had eaten into her lips, the lining of her nose, her mouth, burning deep within her chest.
Dan was alerted by the sound of the alarm and orange flashing lights. It was not the first time, he’d had to reset sensors on several occasions from false readings. But there was always the doubt in the pit of his stomach that something dreadful had happened. Checking the gas panel outside the office, he could see it was an HCl sensor that had alarmed.
He followed the drill and went down to the technical lab and began donning his self-contained breathing apparatus, checking that the cylinder pressure was full and the face seal airtight. He had to work with a buddy. This time Paul, the lab supervisor, joined him. They burst through the steel fire exit door to the side yard.
It was still daylight, the insides of the cages cast in shadow.
‘My God! Oh Fuck! Over here!’ Dan exclaimed, muffled through his mask. He’d caught the colour of her blouse, Tara was crumpled on the concrete floor. Together they lifted her, and placed her on the grass at the opposite side of the yard. Her lips were blistered, she gasped and groaned as they put her down. Dan uttered a sigh of horror mixed with relief
‘We’re getting help Tara, and water’ and under his breath, ‘Thank God you’re alive!’
Paul had dialled 999 for the ambulance and fire brigade. They briefed the fire brigade that toxic gases were involved and self-contained breathing apparatus (SCBA) may be required.
Paul came back with a jug of water, and gauze from the first-aid box, to cool her skin to help halt the burn. Mike was there as a trained first-aider to help make Tara comfortable until the ambulance arrived.
‘Jesus!’ Mike gasped.