Hello, Robert,
In my former life designing high-end broadcast facilities (1974-2004)
it was common before the Montreal Protocol (1987) to install
Halon(tm) fire suppression systems in equipment rooms and tape vaults.
The Authority Having Jurisdiction (AHJ--typically the fire marshal or
building department) would often require a dry-pipe, pre-action fire
suppression system in addition to the gas-discharge system to protect
the building if the gas system did not suppress the fire.
With all the uncertainties following the Montreal Protocol, and the
expenses of the dual systems, most of the clients I worked with opted
for the dry-pipe pre-action system as the single system.
There appear to be regional variants to this system, and with your
comment about "capping" the existing system, and the fact that you
mentioned a dry-pipe system without the word "pre-action" attached
leads me to believe that you may have a flooding or deluge system.
When we discuss a dry-pipe pre-action system, it works like this:
There is a standard fire-alarm system comprised of smoke and heat
detectors, and it is typically cross-zoned so that the first detector
to trigger provides a warning alarm and only after a second detector
triggers is the valve opened that lets water into the dry-pipe
pre-action system.
However, the dry-pipe pre-action systems that I have seen still have
sprinkler heads on the pipe drops, so, in addition to the flooding of
the pipes by the pre-action valve, sufficient heat in the vicinity of
the fire is still required to open the adjacent sprinkler head(s) to
actually extinguish the fire, localizing and minimizing damage from
fire suppression activities.
After the pre-action valve goes off, most protocols require draining
each and every drop (joy!) so there is a mess factor associated with
this. Then the system is pressurized (sometimes with nitrogen to
inhibit corrosion) and if a sprinkler head is knocked off, there is a
trouble alarm, but no water flows.
A design caveat with any of these systems in a multi-story building
is to understand how the water will flow on upper floors vis-a-vis
lower floors. This may require sealing of floor slabs and
purpose-built or simply thought-through drainage paths. Remembering,
of course, that concrete is essentially porous.
There is yet another level of protection that could/should be
included and that is a VESA sniffer system that is a VERY sensitive
smoke detector and it can run an early-warning alarm (not necessarily
opening the pre-action valve) that can identify the earliest stages
of combustion. This is most effective in a building with a 24/7
security operation, because if you add remote personnel's travel time
to the building, the advantage of the early warning is probably lost.
I have investigated at some length the oxygen displacement system
designed in Europe and sold out of my (now) local area (Toronto, ON)
www.controlfiresystems.com and was interested in them, but they were
never specified into a project that I worked on. This system uses
argon gas and is perhaps less of a risk to human life than carbon
dioxide flooding systems which can be fatal. A great risk with carbon
dioxide is that since it is heavier than the normal air mixture, it
will flow "down hill" and may suffocate people on lower floors.
One of the interesting things that Control Fire Systems seems to
offer (and I haven't talked with them for 4-5 years) is a method
where they have one shot for each of two spaces (or one shot for
either of two spaces in an alternate scenario). BUT in the one shot
for each of two spaces approach, I think they can cross-link it so
that two shots can be delivered to one space.
The challenge with all of these systems is what to do if the shot(s)
of gas do not extinguish the fire, especially in a multi-story
structure where structural integrity is required. This is why the AHJ
is usually interested in a backup water system even with the gaseous
discharge systems.
While not impossible, even wet-pipe sprinkler systems rarely leak.
From the TV industry, there are two stories that I'm aware of:
(1) The PBS fire in the 1980s where there really wasn't a fire at
PBS, but at the post office in La'Enfant Plaza above the PBS
facility. The sprinkler discharge dripped down and the moisture
damage destroyed the entire network centre.
(2) Recently at a major network facility in NYC, the studio lights
came on by themselves and the HVAC was turned off. The studio got hot
enough to trigger the sprinklers and some damage was done, mostly
waiting for a fire department OK to turn the sprinklers off.
In the 1980s and 1990s, ON-OFF sprinkler heads became available, and
some AHJs and insurance companies (that's always an important
concern, what your insurance company and/or Factory Mutual allows)
allowed them and they were/are UL listed. However, at one point some
of these were recalled as being defective. I do not know the outcome
of that or if any are currently offered, but if they are and all the
approvals are available, they limit the exposure even further.
One other thing to consider is a well-researched disaster plan so
that IF something happens you know what exactly to do and who to call
to start the freeze-drying process. Even if your vault is gas-only
protected there are still things that could happen on other floors.
I hope this helps a bit.
Cheers,
Richard
At 09:11 AM 8/8/2006, you wrote:
>All,
>
>We are strongly considering the idea of capping off our current dry pipe
>
>fire suppression system and installing a cleaner, gas-based, oxygen-
>deprivation system in our collections area. Before we begin a thorough
>
>investigation into this idea, I was hoping to receive information from
>
>fellow subscribers. Has anyone on the list engaged in similar projects?
>
>If so, what solution was implemented and at what financial cost?
>
>Thank you,
>
>Robert Ryals
>Claude Pepper Library and Museum
>Florida State University
>[log in to unmask]
>850-644-9217
>
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Richard L. Hess email: [log in to unmask]
Aurora, Ontario, Canada (905) 713 6733 1-877-TAPE-FIX
Detailed contact information: http://www.richardhess.com/tape/contact.htm
Quality tape transfers -- even from hard-to-play tapes.
A posting from the Archives & Archivists LISTSERV List sponsored by the Society of American Archivists, www.archivists.org.
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In body of message: SUB ARCHIVES firstname lastname
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Problems? Send e-mail to Robert F Schmidt <[log in to unmask]>