Flames don’t stand a chance at the Bieudron plant

The fire extinguisher systems for the group alternators and transformers have been replaced as part of the extensive renovation of the Bieudron plant. These systems work by using a gaseous extinguishing agent. The gas is stored in pressurised cylinders kept close to the areas in need of protection. In the event of a fire, it is directed to the site by a pipeline network.

Smothering the fire

The extinguishing agent is released from nozzles spread around the equipment in need of protection. This brings oxygen levels down rapidly below the threshold required to smother the fire and stop it reigniting. After the extinguishing systems in the first group had been renovated, HYDRO arranged bump tests in real conditions. These involve releasing all the gas in the 48 cylinders and measuring the concentration of oxygen at various locations in the site.

The extinguisher cylinders are ready to go into action in the event of a fire.

Full scale testing essential

Passing the test depends not just on the rate measured, but also how long it is maintained. Temperature, humidity and pressure are also logged to track how the atmospheric conditions change during the test. The rehearsal revealed that theoretical calculations do not always reflect reality. Only testing guarantees that the sizing parameters are met and allows them to be adjusted if required to comply with the relevant regulations.

Expansion of the gas in the cylinders generates ice on the pipes.

View of the site transformer before and after gas is released.