some time ago I wrote a small application for ammonia storage in chemical factory. Just some measurements, valves and communication to SCADA system.
One day, the guys from the factory asked me to perform a routine check of the system. OK, I arrived to site and had a call with control room about the tests.
One of the prescribed tests was simulating overpressure in the storage and checking if the alarm is sent to control room properly. The emergency valves were electrically disconnected to prevent leakage of the ammonia.
Everything went smoothly, alarm was raised, the control room confirmed alarm so I switched back to real measurement, when...
What the hell? I hear sirens. I just ran out from the equipment room and I saw four red emergency trucks arriving in front of the room. Something went terribly wrong. Maybe the electrician guys disconnected the wrong valves and ammonia leaked due to simulated alarm? My world went black. Emergency situation in the town, probably I will be fired from the company.
I found the leader of the emergency group and I shouted at him: "It was my fault, how dangerous is the contamination?"
The guy replied: "What contamination? We were just asked for a presentation for local TV."
Damn, I will never forget that day.