Quick-Response Reduction Apply to Preaction?

7/21/2020

I have a question that stems from NFPA 318 (Protection of Semiconductor Fabrication Facilities), Chapter 11, Section 11.1.4.2.

11.1.4.2* Automatic sprinklers for cleanrooms or clean zones shall be installed in accordance with NFPA 13, and shall be
hydraulically designed for a density of 8.15 L/min·m2 (0.20 gpm/ft2) over a design area of 278.8 m2 (3000 ft2).

For a clean room 11.1.4.2 mentions 0.20 gpm/sqft density over 3,000 sqft design area. We're considering quick-response standard-spray sprinkler coverage under section 11.1.4.4. The client is requiring a double-interlock pre-action system, so under NFPA 13 11.2.3.2.5 the remote area must be increased by 30% without revising the density.

Can we omit the 30% increase in sprinkler operation under NFPA 13 11.2.3.2.3 since we are using quick response sprinklers?

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Dan Wilder

7/21/2020 09:48:58 am

Quick response reduction is limited to wet pipe systems only Section 11.2.3.2.3.1 (1) 16' Ed.

Jesse

7/21/2020 10:15:05 am

Would be nice but sadly, no. QR reduction is wet system only.

Matt Clegg

7/21/2020 11:08:42 am

We have a similar situation, would the consensus be that we could use the QR reduction if the system is a wet system? I am curious what the communities opinions are on this.

Tan N.

7/22/2020 01:29:30 am

In fact you have to increase the remote area even more, because more sprinklers will activate before the system is filled. I think that is the reason why QR is wet system only.

Franck

7/24/2020 03:36:19 pm

(personal opinion)
It could be problematic with QR and double interlock (or dry system -i.e. not a wet system) as you may open more heads before water arrives to the open sprinklers as with standard response.
This is probably why NFPA does not recommend a surface reduction.

Then, the insurance loss prevention engineer’s point of view: for new systems, I always apply penalties (+ 30% for dry systems or slopes) but never the reductions.
I am using reductions for evaluation of existing systems after a change of occupancy.
For example, you had an OH gr 2 occupancy and it is now an EH gr 1 occupancy, while my actual density is not good with the existing water supply. Can I retrofit the system and have a correct density just by changing ordinary temperature sprinkler heads with high temperature sprinkler heads ?
While for a new system, I will use the EH gr 1 curve AND high temperature sprinkler heads AND NO additional reduction.

But this is a conservative approach (I work for an insurance).
But it can save a lot in case of future modification and does not cost that much more for a new project.

Quick-Response Reduction Apply to Preaction?

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