trapped water in preaction system
trapped water in preaction system
(OP)
Hello,
I am assigned Single Interlock Preaction System Design at Army Garrision Oversea. The Spec was pre written before the system design. The reason of Preaction System in the Spec is in question. The building has no valuable equiptment. There are 15 jail cells over 13,000 sq.ft. free standing Admin Building. There is suppose to be no heating provided in the building except at the riser room during winter time. Temperature falls -20 degree. The building is not heated and there are approximately 110 pendant sprinklers to provide proper coverage below deop ceiling at office areas. I am not as familiar with selection of pendant sprinklers in preaction systems. What is common practice s in the east cost? I am assuming weather is just as cold in east coast. What's likelyhood of installing wet pendant sprinklers instead of dry sprinklers in preaction systems? Do wet sprinklers truely crack as trapped water in arm over drop subject to cold weather? There is a huge budget difference between two type of sprinklers. Beside, with all dry pendant sprinklers, I am not confident the intension of preaction system in the project specification is well served. Any feedback will be appreciated.
I am assigned Single Interlock Preaction System Design at Army Garrision Oversea. The Spec was pre written before the system design. The reason of Preaction System in the Spec is in question. The building has no valuable equiptment. There are 15 jail cells over 13,000 sq.ft. free standing Admin Building. There is suppose to be no heating provided in the building except at the riser room during winter time. Temperature falls -20 degree. The building is not heated and there are approximately 110 pendant sprinklers to provide proper coverage below deop ceiling at office areas. I am not as familiar with selection of pendant sprinklers in preaction systems. What is common practice s in the east cost? I am assuming weather is just as cold in east coast. What's likelyhood of installing wet pendant sprinklers instead of dry sprinklers in preaction systems? Do wet sprinklers truely crack as trapped water in arm over drop subject to cold weather? There is a huge budget difference between two type of sprinklers. Beside, with all dry pendant sprinklers, I am not confident the intension of preaction system in the project specification is well served. Any feedback will be appreciated.





RE: trapped water in preaction system
RE: trapped water in preaction system
If single interlock or non interlock, I don't believe you need to slope, but am not positive without looking it up. However, you can grid a single interlock system. You will still need dry pendents if you are in unheated areas.
Travis Mack
MFP Design, LLC
www.mfpdesign.com
RE: trapped water in preaction system
First of all what is your responsibility or scope?
Then we can help you. Are you a designer, estimator, project manager, etc.
RE: trapped water in preaction system
RE: trapped water in preaction system
RE: trapped water in preaction system
RE: trapped water in preaction system
RE: trapped water in preaction system
RE: trapped water in preaction system
You really should question single interlock, because any spurious trip of the detection system (without a corresponding fused sprinkler head) would fill the pipe and then it could freeze in the piping.. This would happen reGARDless of dry pendents or no dry pendents..
Why not go double interlock? But don't forget about institutional heads.. I would doubt they make dry pendent institutional heads?? You got yourself a real interesting one there. Good luck.
I would push back politely. Buildings owners/users are building owners/users, regardless if they are a private company or the Army.. They "think" they know what they want to meet their operational goals for the facility, but they don't have the expertise to decide the types of sprinkler system to be used.. Sometimes they might decide these kinds of things anyway, because they feel like they have to put their thumbprint and get the best/fanciest/most advanced system; They saw it at a tradeshow, etc.
For basic conformance to UFC 3-600-01, my wetpipe system checklist might be somewhat useful for the other parts of your system:
ht
RE: trapped water in preaction system
RE: trapped water in preaction system
So are they using some type of detection to trip it???
RE: trapped water in preaction system
Spec is Single Interlock Preaction w/Electric Actuation
RE: trapped water in preaction system
RE: trapped water in preaction system
Detection can be placed behind a service grill, the biggest problem is that you usually only have one detector per cell. A delay can be included in the alarm / detection system. Systems can also be controlled remotely, from a control room.
Preaction systems in jail cells are not overkill or overspec. They are preferred.
Most cell protection is sidewall type sprinklers. Depending on the service shaft / building design you may be able to avoid dry heads and still provide proper drainage.
Smoke detectors are ok, VESDA is better.
You should also have more than the usual compliment of spare sprinklers for two reasons:
1. The guards will have to have a couple to take apart - they need to be able to find every piece that comes off the sprinkler head. They usually make a board with all the parts on it.
2. They will go through several extra in the first 6 months.
BTW - one jail I know of lets the cell fill up with a couple of feet of water (allegedly.) Claims to have stopped tampering issues. Makes for a good story.
-20°f sounds incredible for a normally occupied location.. are you running pipe outside the building envelope?
Good Luck!