I'm working on a project with a foam-water sprinkler system using NFPA 16 Section A.5.4.2 as a guide.
There are four rooms with different dimensions that need to be protected and we have a deluge valve on each room. My client wants to have a single proportioner for the four rooms.
Can I achieve the 3% concentration in each room even though the orifice is size based on the largest room?
Or do I have to provide a proportioner for each room to be able to achieve the 3% upon discharge on any room?
Any guidance here is much appreciated.
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8/17/2022 08:23:57 am
Yes, it can be done but you'll need to confirm flow rates for each of the systems falls within the parameters of the proportioner for low/normal/high usage or get one that has a flow control aspect to ensure the mix is correct.
8/19/2022 08:42:51 am
8/17/2022 08:28:30 am
This a question that needs to go to the appropriate manufacturer technical representative.
8/17/2022 09:39:27 am
I echo what both Dan and Glenn said.
8/17/2022 11:00:34 am
Proportioners mix in proportion above the minimum flow in the listing using the pressure difference in the restriction of the Venturi orifice. Determine minimum falls above minimum listing. Determine max flow area, and be sure to size foam concentrate volume and tank size based on the source calc for the maximum area. Source calc is the flow rate when there is 0psi safety margin, which is the same as supply pressure being equal to demand pressure + friction loss. The reason is, when the system activates it will flow to equilibrium.
Michael p venneri
8/21/2022 10:18:19 am
Yes you can use one proportioner. You need to make sure the lowest foam flow is in range with the lowest system demand. I would say that if you are using an orifice plate, the flow will be dependent on the orifice plate. Suggest a balanced proportioned that would adjust to whatever flow the system is that discharges. Again know your system demands and match the proportioner. You could use a bladder tank to avoid an in jection pump.
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