Inside a pharmaceuticals plant, fumes from hydrochloric acid (HCl) and ethylamine hydrochloride intoxicated 2 subcontractors commissioned to dig a trench to lay new pipelines.

At 7:45 am, a reaction was triggered involving 113 kg of chloroacetyl chloride inside a 4,000-litre reactor. The HCl formed during the reaction was normally brought down by a scrubbing column filled with soda. Subsequent to a column malfunction, white smoke exited the column vent and intoxicated 2 workers carrying out their tasks adjacent to the facility workshop.

First responders arrived on the scene and 2 fire-fighters were also intoxicated; all 4 victims were transported to hospital, one of whom required a 24-hour observation period. The other 17 employees present onsite remained confined in a laboratory where they were later medically examined. The employees resumed their work around 10 am following measurements of oxygen rates in air and the pH of water in the trench as well as verifying the absence of residual chlorine.

The column had been used to bring down excess ethylamine during a previous synthesis operation. The HCl not absorbed by the column reacted with the ethylamine present inside the scrubbing tank, causing an emanation of whitish fumes.

The operator drained and washed the scrubbing tank, cleaned all tank pipes leading to the column, verified both column pumps and analysed the scrubbing soda. The ethylamine reaction process was also modified: any excess was eliminated via the aqueous effluents and no longer by the column. Over the medium term, the operator included regular tank drainage and maintenance of the scrubbing column into its preventive maintenance plan, in addition to expanding the column’s scrubbing capacity by raising the gas/liquid exchange capacity. The possibility of combining the highest-capacity vents on a single general scrubber was also studied.