Active fire fighting for the switchgear room 1

[krisys]

This is regarding the requirement of fire fighting system for one of the critical switchgear room in the offshore platform. Presently it has active fire fighting system. This is an existing switchgear room having this fire fighting (FF) system from the beginning.

As the existing FF is now outdated, they want to replace it. But while replacing it the new FF is not active FF system.

For the benefit of the readers:
Active FF system:
Automatic fire/smoke detection and activating the release of fire extinguishers, say CO[sub]2[/sub] gas.

Passive FF system:
There will be only the automatic fire/smoke detection and alarm. Based on the alarm, the fire fighting team shall go and extinguish the fire manually.

In my view the new system shall also be active FF system. But due to the cost, people are going for the passive FF system.
I would appreciate if someone can share your experience and give your thought.
It can be either in favor of my argument or against. Both sides of argument is welcome.

 

[Marmite]

I would think that this would be a no brainer if it is indeed a "critical switchgear room on an offshore platform".
There is an existing active fire fighting system in place, so someone must have decided at the time that the risk of a fire happening, or the consequences of a fire were so significant that it warranted a fixed installation.
So what has changed? Is the switchgear less likely to blow up tomorrow than it was yesterday, or are the consequencies no longer significant?

This needs a robust risk assessment process to be carried out. Cost is a factor, but I doubt that reluctance to spend money replacing an outdated fixed fire fighting installation would be enough of a defence to keep you out of jail if s*it happens. Not all components of the system will need to be replaced in any case.

A fixed fire fighting installation avoids the need for someone to put their life at risk by going into a blazing switchroom. It acts extremely quickly and can limit the damage to the switchboard to a single panel, which leaves open the possibility of repair and restoration as opposed to total loss, and all the consequences. How do the fire fighting team plan to extinguish a fire manually? You can't beat gas deluge for speed and lack of consequential damage.

You've not mentioned a voltage, but there is a misconception that you can't get sustained fires with modern vacuum or SF6 switchgear and polymeric cables. This is not the case. I used to work for a utility in the UK that had a 33/11kV substation with the 11kV switchgear and all 33kV protection and transformer AVR panels in the same room. There was no active fire suppression. A fire developed in an 11kV cable termination with destroyed the switchboard and all the protection panels. It was subsequently decided to return to fire rated segregation that wasn't originally thought necessary after the company moved away from oil switchgear.

Regards
Marmite

 

[davidbeach]

My favorite approach is a dry, pre-action fire suppression system. Dry pipes to closed sprinkler head, charged under rapid loss of pressure or other predefined conditions. Then, the critical part, use the release of water into the pipes to dump the switch gear, shunt tripping anything and everything. You're going to have a heck of mess to clean up afterward, but it will be a walk in the park compared to what it would be if the gear was still energized when the water hit. A half second of water flow time is all the time in the world to get things deenergized. False alarm or not, it doesn't matter, because water on energized gear is far worse than an unnecessary interruption.

 

[krisys]

Marmite,
Excellent answer. Thank you. It is a 22kV switchgear room connected to the main power generators of the facility. If any damage in this switchboard has long lasting consequences.

David,
Previously (till now) we were using the Halon (Brand name) gas fire extinguishing agent at all the locations of this facility. As Halon is a green house gas, they are now replacing it with another gas called Novec (brand name). Originally even in the switchgear room it was proposed to have Novec (fixed system) in place of Halon system. But later due to the space contraints to accommodate the Novec gas cylinders in the place of the Halon cylinders, they have decided to go for the manual fire fighting system.

 

[ScottyUK]

My experience of substation fire suppression mirrors that of Marmite - a CO[sub]2[/sub] flood to knock down the fire through oxygen displacement. Halon systems generally have been confined to computer-room type facilities.

I wouldn't expect anyone to personally fight an established fire in a switch house. When I'm authorising personnel for work in substation environments my instructions are very clear: if there is a fire, get out and stay out. Trip it remotely and/or let the protection clear the fault and then leave the fire to burn itself out. If the emergency services are in attendance then provide them with sufficient information to make their own assessment of the risks.