Two divers, when disconnecting a flange on a pipeline, encountered what appeared to be water escaping from the flange.
The fluid was subsequently found to contain toxic volatile condensate compounds.
When the first diver returned to the diving bell, the liquid on his suit/umbilical contaminated the atmosphere of the bell, to a point where he and the bellman became irrational. They had to be assisted by the second diver who returned to the bell later and was still wearing his helmet.
The incident highlights the need to assume that any fluid emanating from a pipeline could be hazardous. This specific incident is currently subject to a detailed and comprehensive investigation by those involved.
It is recommended that members check that their guidelines to divers contain such a caution.