Hello Chris,
I think that your question about fire extinguishing systems comes under the heading, "it depends". There are so many factors to consider when designing and choosing a system, it is just about impossible to come up with one simple answer. One consideration in replacing an old Halon system with a new extinguishing-gas system is overall safety -- depending upon the layout of the building, it may not be within code to cover the entire building with one system. The gas may not be toxic, but it displaces air when deployed, thus potentially making it difficult for people to exit if they have to walk too far. If such a system is permitted, the overall cost may be considerable. About the only public space (in other words, not a storage room) covered by a gas system I have seen recently is the clock exhibit gallery at Old Sturbridge Village; unfortunately, I have no idea how old their system is, nor its cost, but the latter must be high, considering the volume of the room.
As for choosing between gas and water extinguishing systems, a wise and experienced conservator once said, "If it's wet, we can dry it out, but if it has turned into toast, we can't turn it back into bread." Of course, the latter part of that statement pertains to any extinguishing system, but also she was somewhat allaying fears about using water systems. You may wish to research the choices of wet-pipe, dry-pipe, and water mist systems; you should not proceed based solely on what my opinion may be, and there are lots of other sources of information. First, I would suggest being cautious about dry-pipe sprinkler systems. In my own experience (and in research about other museums, such as the Dewitt-Wallace Gallery at Williamsburg) dry-pipe systems can become leaky and unreliable over time, because the pipes are not really dry. After the system is built and tested (and thereafter tested each year) there is always a little water left in some of the pipes, creating corrosion and sludge. In our museum, we eventually had a leak caused by that corrosion, though as far as I know, no remedies were pursued later to overhaul the entire system. Therefore, leaks will probably develop soon, and possibly in places less convenient to work on than the basement utility areas where the first noticeable leak appeared. One might expect wet-pipe systems to develop worse corrosion problems, but in fact it is the combination of moisture and air in the "dry" systems that is the most problematic. Water mist systems are considered very effective, even though they use much less water than traditional sprinklers, and the water pipes are much smaller, as well. However, since mist systems operate under rather high pressure, materials and installation can be quite costly, and of course, everything is subject to codes that apply in your area. Your fire marshall can offer guidance.
Something else to consider regarding sprinkler systems is that individual sprinkler heads can be activated in the event of fire, so you do not necessarily have water spraying everywhere. Similarly, there are controls that shut off the water once the fire is extinguished. Still, water is the extinguishing agent, so in collections areas, at least some objects are likely to become soggy. In the end, water systems are very effective, and they are not dangerous to people.
The next step you take might be to look up the AAM security committee, and read about the advice from those experts.
Best wishes,
Bruce
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Bruce MacLeish
Curator Emeritus, Newport Restoration Foundation
Newport RI
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Original Message:
Sent: 05-22-2017 11:34 AM
From: Chris Godbold
Subject: halon fire system in historic house
Good Morning All,
At the George Ranch Historical Park, one of our historic homes was outfitted with a halon fire extinguisher system when it was restored back in the late 1970s. Our partner organization, which owns the house, is considering replacing the system with a water based sprinkler system. What is the best option here? Does anyone out there have experience with replacement of a halon system in a historic house? We would certainly prefer another gas based system rather than risking great water damage on top of fire damage. Can a replacement system for halon use the same hardware? I have no idea what the present condition of the system is after 40 or so years though as far as I know there are no leaks or damage. Portions of the system are located in the basement which has been known to have a little water in it from time to time.
Thanks in advance for any help you can provide,
Chris
Chris Godbold
Chief Curator of Collections
Fort Bend County Museum Association
Fort Bend Museum – George Ranch Historical Park
cgodbold@fortbendmuseum.org
www.fortbendmuseum.org
www.georgeranch.org