Use QR & Residential in Same Compartment?

5/8/2025

Renovating an 11-story hotel using residential sprinklers in accordance with NFPA 13 (2019).

Calcs based upon S x L (4 sprinklers at .10 density) or manufacturer data sheets (which ever requires greater demand).

Sprinklers need to be 175° due to less than 24" from the side of the wall mount diffuser. There are a few rooms that require a SW throw of 20'-4" (22'-0' per data sheets). However, many manufacturers do not manufacturer this 22 ft throw in 175°, only 155°.

Can I use a quick response (Viking VK630) SW that throws 22 ft along with the residential sprinklers in the same compartment?

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8 Comments

Pete H

5/8/2025 06:20:56 am

I don't see a specific code restriction in 2019 to prevent this (provided the residential head is quick/fast response, if the residential head is not quick/fast response, you've found a magical standard response residential head I've never heard of before.)

You're in 13, so you were going to do a 900-1500 square foot calc with all heads at least operating at .1 density as is, so it's not like there's a downside to the QR head because you're not going to be allowed to a 4-head residential calculation anyway... though similarly if you are that worried, there's not really a cost difference if your pendants are residential or just regular QR concealed in this application.

Ed T

5/8/2025 08:20:34 am

NFPA 13, 2019 12.1.4 states that if residential sprinklers are installed in a compartment, all sprinklers within the compartment shall be residential sprinklers

Jesse

5/8/2025 08:31:16 am

I would say no based upon 2019 NFPA 13 12.1.4

12.1.4

Where residential sprinklers are installed in a compartment as defined in 3.3.38, all sprinklers within the compartment shall be residential sprinklers.

So, unless the VK630 carries a residential listing, I don't think that would be acceptable.

Jonathan W.

5/8/2025 08:57:09 am

Aside from the code requirements, I believe it's important to understand Residential Sprinklers are designed differently and are tested to meet specific life safety criteria. This includes spray pattern, compartment tenability levels (oxygen, temperature, carbon monoxide), and response element. Residential Sprinklers are designed to wet the walls VS providing a water density at the floor level. They are designed to enhance the survivability within the room of origin compartment.

It would not be appropriate to substitute a non-residential sprinkler in this space unless the sprinkler is listed specifically for residential applications.

Casey Milhorn

5/8/2025 08:59:38 am

I would advise doing anything you can to get that separation and use that 155, otherwise you will need to use QR light hazard sprinklers, which then kicks you out of the 4 head design.

Jack G

5/8/2025 09:03:37 am

The sprinklers within a room must have the same response time so no. 2019 NFPA-13: 9.4.3.2.
So make them all Qr sprinklers and do a reduced design MRA per the chart ?
or residential sprinklers and do a 4 head MRA calculation ?
A 900 sq ft calc might be at least be 6 rooms. The area above for 2 rooms appears to be 28x 11.
Sprinkler flow within closets bathrooms if they fall into the MRA are required to be included in the calculations,
Would room design method or small room ( 800 sq ft) rule be a better design approach ? I would try room design— 1 room and add 2 heads in the corridor.
Is the shaft wall between the bathrooms fire rated? Requires a 15 minute thermal barrier.
How about common wall between the rooms?
All construction must meet/rated per the applicable code.,

Jose R Figueroa

5/8/2025 12:32:22 pm

155°F Quick response is acceptable. I don’t see any restriction in NFPA 13 2025.

O.P.

5/8/2025 02:30:51 pm

Thanks all for the responses - UPDATE - I missed NFPA 2019 12.1.4 that many had referenced - I mistakenly got caught up in 12.1.2 and A12.1.6.1- Interestingly enough, I also made the mistake of looking for a 5.8 or larger orifice SW to throw the 22 ft in 175° temp. I should not have limited my search by orifice. Viking residential SW VK486 9 4.0 k) throws 22 ft , 175° with less psi / gpm than the larger orifices. Todays lesson - slow down

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