View Full Version : Wet vs. Dry Pipe Fire Supression from RCAAM

02-02-2011, 09:06 AM
Some discussion from RCAAM concerning wet vs dry pipe sprinklers:

Dear All,
This very interesting and enlightening conversation (below) debating the benefits of wet pipe vs. dry pipe fire suppression systems traveled the list last summer. I saved it because we are about to build a new addition and sprinklers are in the plans.
In the earlier e-mail exchange, wet pipes were the preferred option, but I think they were primarily discussed in terms of collections storage areas. Our new addition will have both both collections storage and gallery areas. Someone here has suggested that we go with a wet system in the storage spaces and a dry system in the galleries. The reasoning given is that lenders may require/prefer a dry system where their works will be shown. I have never personally encountered such a request and have reservations about installing the dry and/or a mixed system approach in the new building.
Does anyone have an opinion on this? Have you encountered such requests or do you request dry over wet pipes in the display areas of organizations you lend to? Has anyone raised the issue with you before?
Your thoughts on this (as soon as you can send them) would be very much appreciated!
Frances Lloyd-Baynes
Collections Registrar
American Swedish Institute

Forwarded conversation
Subject: [RCAAM] wet pipe versus pre-action dry pipe
From: Warren Woods <warrenw@hnoc.org>
Date: Tue, Aug 24, 2010 at 9:36 AM
To: RCAAM@si-listserv.si.edu

Greetings from New Orleans.

I have been hearing and reading conflicting reports on the current museum standard for sprinkler systems, especially wet pipe versus pre-action dry pipe.

Can anyone shed some light on this topic for me?

Thanks as always,

Warren J. WoodsCollections Manager/Exhibitions CoordinatorThe Historic New Orleans Collection533 ----------
From: Bruce MacLeish <bruce@newportrestoration.org>
Date: Tue, Aug 24, 2010 at 11:02 AM
To: RCAAM@si-listserv.si.edu

Hello Warren,

First of all, let me say that I loved visiting your museum a few years ago, and I look forward to getting back there someday.

As for your question, I can’t say that I have all the answers, and perhaps some other sources could be of use to you, such as the NFPA, the National Park Service, and the AAM’s Museum Association Security Committee. For starters, I checked my binder of material from the Canadian Conservation Institute, and I can quickly quote their recommendations: “The cost of automatic sprinkler systems can be kept low by selecting conventional wet-pipe systems; on/off sprinklers, pre-action systems, and cycling systems are more expensive to install and maintain, and do not necessarily provide better protection. Many of these special systems are plagued with maintenance problems and are hardly ever required in museums.” So, there you are. However, that information was published about ten years ago, so it may not indeed be the last (i.e., latest) word on the subject. It’s a start. Note that neither CCI, nor I, will address water-mist or chemical systems.

In my own experience, I can relate life with both wet-pipe and pre-action dry-pipe in one of our larger buildings. Fortunately, we do not have empirical data about how well our systems would extinguish a fire, but I think that the historical information proves the value of sprinklers. Our wet-pipe system has been simple to maintain and has not given us any problems in the ten years it has been active. We do have areas of dry-pipe service, originally installed because of a perceived risk of freezing in certain areas. If anyone had bothered to check, it would have been evident that the freezing risk is virtually non-existent, and that would have spared us a good deal of trouble and expense. The dry system involves an air compressor to keep the pipes under pressure, to help hold back the water, until the system is activated. This has happened several times, through faults in the system, and not because of fire. Fortunately, the sprinkler heads kept the water from soaking the museum areas when there is no fire; still, a service call is required, to empty the water from the dry system and be sure everything is once again in readiness. Of course, each incident also involved an automatic alarm that brought the fire department to the building.

To improve performance of the system, we encouraged our service people to raise the air pressure in the pipes (after two false activations in two weeks); although they seemed unsure about the efficacy of that step, it has worked well for the past couple of years. We also installed a secondary alarm to ensure that the air compressor for the system is working properly. The alarm sounds every time the system reaches its low-pressure limit (about once each week) and shuts off when the high-pressure limit is reached. Our security crew, after being scared witless by the loud bell, check to see that the compressor is running as it should. They note on a log sheet the air pressure at various times of day, and the compressor cycling. I should also add that when the system is activated, whether by accident or for a test, the dry pipes have to be drained, and some of the drainage points are behind exhibit walls, and in other areas where the disposal of many gallons of water is a pain in the neck. Notice how none of this information involves the wet-pipe system? As I learned from a colleague at an AAM session, bits of moisture left in a dry pipe can eventually rust through the pipe walls, leading to failure and likely flooding. I suppose no system is perfect, but the dry-pipe system seems much less perfect than the wet-pipe.

I can only add that having the system tested is very important. You do not want to be the careless fellow who neglected something like this. We discovered that for some reason our service company did not have us on their list after the system was installed, but fortunately there were no serious repercussions. Eventually, the service company let us know that even though a flow test (blowing large amounts of water through the valves and pumps, and producing a large hole in the ground, if you’re not careful) was not required, it seemed like a good idea. Otherwise, you can’t be sure that the all-important pump even works. Well, of course. I can only hope that we have reduced our ignorance to a more reasonable level through these experiences, which I am willing to share with colleagues, so that you may escape some of the less-desirable consequences.

Comments are welcome, and thanks to others for your help in the past.


A. Bruce MacLeish
Director of Collections
Newport Restoration Foundation

From: Warren Woods <warrenw@hnoc.org>
Date: Tue, Aug 24, 2010 at 11:41 AM
To: RCAAM@si-listserv.si.edu

Dear Bruce:

Thanks so much for this useful information.

Please let me know when you visit New Orleans again and I need to get up to Newport. It is on my list.

Thanks again,
From: Bruce MacLeish [mailto:bruce@newportrestoration.org]
From: Melissa deBie <melissa.debie@gmail.com>
Date: Tue, Aug 24, 2010 at 12:43 PM
To: RCAAM@si-listserv.si.edu

I did a lot of research into dry vs. wet a couple years ago. I have to say that wet pipe won because of the personal experiences as well as stories about other dry pipe systems.

I was in a building that was about 10 years old with dry pipe. 10 years was about the expected lifespan for the dry pipes because after that we had to continually replace pipes all over the building. Even though they're supposed to be 'dry' pipe, they run water through when the system is tested. No matter how good the system is, there's going to be a little water left somewhere. A little water in a mostly dry pipe system=corrosion. The pipes were basically rusting out from the inside. (We also noticed that once the pipes were done we started getting leaks at the joins. They weren't just water leaks, they were brown/black gunk leaks from the extra buildup inside. Dry doesn't always equal empty either.)

Go with wet pipe. In the end it'll be a lot cheaper and less overall maintenance.


From: Frank E. Thomson <FThomson@ashevilleart.org>
Date: Tue, Aug 24, 2010 at 1:49 PM
To: RCAAM@si-listserv.si.edu

We also have a dry pipe system and it does require a lot of maintenance for the compressor and the pipes that get flooded and drained and thus have to have rusted sections replaced periodically. In the end whenever there is a drop in pressure, the pipes flood. If there was a hole in the piper, water would come out at this point. So having a dry pipe system doesn’t prevent water problems and may actually increase the likelihood of leaks.

Frank Thomson, Curator
Asheville Art Museum

T. Ashley McGrew
02-02-2011, 11:20 AM
I am curious about this as well.
I have heard from a couple of people that in addition to having pipes rusting out over the long run when using "dry" systems another drawback is within a very short time the oxidation within the pipes can be enough to make the water red potentially resulting in the staining of objects that the water contacts when the system is activated.
I have also heard from a reliable source of one instance where when a dry system was set off by accident and the water rushing down a large pipe actually blew a joint apart.
I think this may have been at a 90 degree bend or something. I am not sure but I believe this occurred before full occupancy of the building and that no collections materials were damaged, but it sounds pretty danged scary!
I would like to know more about the misting systems.

Paul Brewin
02-02-2011, 11:41 AM
I sat in on part of the presentation at AAM -- interesting topic, most were advocating the wet system over the dry. We have FM-200 for our vaults; when I asked them about that system they had concerns because although it's a "clean agent", in the event of a fire extinguishing event with FM-200 it releases "some" hydrofluoric acid, and that signals concern for them.

02-03-2011, 09:26 AM
More from RCAAM:

This corrosion can happen in as little as 2 years. It happened to us.
I vote wet pipe for everything, and have been told the same by numerous
museum operations and security managers for the past 15 years.
Gale Rawson
Museum Registrar
Pennsylvania Academy of the Fine Arts
128 North Broad Street
Philadelphia, PA 19102

-----Original Message-----
From: Registrars Committee of the AAM [mailto:RCAAM@SI-LISTSERV.SI.EDU]
On Behalf Of Anne Lane
Sent: Wednesday, February 02, 2011 4:25 PM

Subject: Re: [RCAAM] Revisiting the wet pipe vs pre-action dry pipe:
galleries vs. storage

"Dry" pipe, it turns out, is a misnomer. When the system is tested, some
moisture remains at fittings and at low points in the system. Over time,
the availability of oxygen combined with this moisture causes your pipes
to corrode. This can happen in as little as ten years. Williamsburg, as
I remember hearing, has switched some of their facilities to wet pipe -
I don't have the link, but someone else might have kept it. Wet pipe
systems do not corrode this way.
Anne T. Lane
Collections Manager
The Charlotte Museum of History
From: Registrars Committee of the AAM [RCAAM@SI-LISTSERV.SI.EDU] On

Patty Silence
02-12-2011, 06:25 AM
Based on experience with wet-pipe, dry-pipe and pre-action dry-pipe, I strongly caution against the latter two. Briefly, the theory bhind them is that the pipes are kept dy inside. This is achieved (between routine maintenance flushings) by having the pipes sloped sufficiently to drain, having plenty of clean-outs (i.e. no little places where water can be trapped), etc. This is next to impossible on long runs above ceilings in galleries. Invariabley, you end up with both water and air in the pipes, and we all know that this combination yields Corrosion. Corroded bits can block sprinkler heads, pin holes can form, and the water that you rely on to put put a fire is very mucky if it can come out properly.
We have pulled all of our dry-pipe systems, finding pin holes, pipes half filled with bacteria and corrosion by-products, and the clear recognition that if we had the worse case scenario, we would not get the suppression we need. Traditional wet-pipe systems are tried and true, avoiding glass-bulb heads is recommended. If you do not have sufficient water available and have space for nitrogen propellent tanks, consider more expensive mist suppression. This is a case where being conservative is the right approach - no fancy gimmicks, just basic good sense.

T. Ashley McGrew
02-20-2011, 11:01 AM
Here is another response from Bruce McLeish one of the best sources of interesting and valuable input you will come accross on a variety of topics. This is another post from the Registrars listserve shared herre with his generous permission.

Re: [RCAAM] Dry Pipe Sprinkler Flush
From:Bruce MacLeish <bruce@NEWPORTRESTORATION.ORG>

I have written to the listserve about this subject before, but have had additional and educational experiences with our dry-pipe sprinklers more recently. Since the time when I wrote the last email on the subject, we have had an inspection and an attempted cleaning of our dry-pipe system. Following the sage advice of some folks from Colonial Williamsburg, I thought we should take a look at our “dry” pipes. Sure enough, a sludge of corrosion and possible biological deterioration products filled about the bottom ¼ of the pipe. Because the pipes do not empty completely of water, after being tested or accidentally activated, there is a very humid environment in there, which is perfect for corrosion and so forth. We can only hope that our vigorous cleaning operations actually had some effect, beyond covering a half-acre of ground with a light coating of muck. Aside from the main hazard of corrosion causing a pipe to leak, there was the possibility that the sludge would keep water from entering a sprinkler head. If the water did flow, if would clearly carry with it the rust-red mud from the pipes. I must say that we did not follow our colleagues’ lead entirely, because they replaced their old dry-pipe system with a new wet-pipe system, and we have not. That is certainly in the cards, a few years from now.

To answer one of Anne’s questions, quite a bit of our system is within plaster ceilings, so we cannot visually inspect those areas. We can guess at the overall conditions, by opening up pipes in the basement, but otherwise we keep an eye on the ceilings for damp areas and rust stains.


A. Bruce MacLeish
Director of Collections
Newport Restoration Foundation
51 Touro Street
Newport, RI 02840