Water and cast iron tools don't mix. In the event of an actual fire the cleanup inherent to removing all the resulting rust would be incredible - let alone needing to replace motors, controls and other electrical equipment. If I were to smash a head with a long board, setting off a deluge by accident I would be very unhappy ....

At the moment I do not have a fire suppression system, but have been looking into installing one. When I started researching the options, I was initially thinking of going with Halon. Not. As an ozone depleting gas, Halon was banned several years ago.

The best option I've seen is a system called Inergen. Inergen is a mixture of nitrogen, argon and carbon dioxide - all available at you local welding supply company. The strategy is to lower the oxygen content sufficiently to prevent and/or stop combustion, but not so low that anyone in the room would be asphyxiated.

From what I've read, the piping and what not is basically the same except for the special gas dispersal heads and tank hookups that are required. I've never priced out a system, but my sense is that if would only add 15-20% to the cost of a typical water system.

One of the largest suppliers/installers is the Reliable Fire Equipment Co outside Chicago.

http://www.reliablefire.com/inergenfolder/inergen.html

I'm sure you could find similar suppliers near any major city.

Usual disclaimers apply - no affiliation, etc.

Brian