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>

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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.

Bruce


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