MeyerFire
  • Blog
  • Forum
  • TOOLKIT
    • ALL TOOLS
    • BUY THE TOOLKIT
  • UNIVERSITY
    • ALL COURSES
    • JOIN THE UNIVERSITY
  • PE Exam
    • PE Forum & Errata
    • PE Store
    • PE Tools
    • PE PREP SERIES
    • PE 100-Day Marathon
  • LOGIN
    • TOOLKIT-ONLY LOGIN
    • UNIVERSITY LOGIN
  • PRICING
    • SOFTWARE & TRAINING
    • STORE
  • OUR CAUSE
    • ABOUT MEYERFIRE
    • JOB OPENINGS
    • BECOME AN INSTRUCTOR
    • HELP/SUPPORT
Picture

Mix K-Factors and Temperatures in Same Room?

2/14/2019

8 Comments

 
Are there any requirements pertaining to mixing fire sprinkler k-factors or temperatures in the same room?

We often come across unit heater placement, so at least on the temperatures I suspect that mixing in the same room happens fairly commonly to accommodate heat sources.

Posted anonymously by a member for discussion. Discuss this  | Subscribe
8 Comments
Corey
2/14/2019 10:02:52 am

Yes, you can mix temperatures within the same area. See NFPA 13, 2016 edition 8.3.2.5 for more detail.

Reply
Dan W
2/14/2019 10:24:14 am

If you are using the different K-Factors to minimize over discharge a system, then not allowed (23.4.4.9.2-16'). 23.4.4.9.3 & 23.4.4.9.4 allows different orifices within small rooms (exposure protection & directional spray sprinklers) with the Annex explanation giving a little more insight.

Reply
PETE
2/14/2019 10:24:22 am

Mixing K-factors is acceptable, however, you will want to either designate areas that certain K-factors are to be used, or be very knowledgeable about fluid dynamics. If you have one K-factor in one area, and another K-factor in another area- both areas should be calculated. This also applies to standard and extended coverage in portions of systems.

I had one instance in which I was designing a deluge system for an industrial chemical complex that was on city water, and I was trying to satisfy and insurance underwriter's safety cushion requirement. I had to use a plurality of screwed pipe sizes and orifices in order to minimize over-flow and over pressure situations, as every head was required to flow.

Reply
PETE
2/14/2019 10:30:44 am

I should add, after reading DAN W's comment above: the example I gave was a directional nozzle deluge system for a pumping station near an exterior dock; in which non-flammable non-combustible liquids were being pumped- mainly ammonia.

Reply
ZS
2/14/2019 01:49:16 pm

Adding to what others have said.
- Mixing temperature ratings is permissible, and fairly common. For example: NYC apartments and condos, I would use regular temp heads throughout, but switch to medium- or high- temp if the sprinkler is too close to a stove, dryer, fireplace, etc.
- Mixing k-factors is NOT allowed for "balancing" or to try and reduce your hydraulic demand. It is (in general) allowed if you need a different k-factor for a specific reason. However - the requirement to separate different k-factors is "by room" or "by area" not by sprinkler system. It is important to review NFPA definitions for these, as the NFPA definitions may not align with an Architect's "common sense"
- As I understand it, mixing Ordinary Response sprinklers with FR/QR sprinklers is NOT allowed.

Reply
Dan W
2/14/2019 05:52:42 pm

For the FR/QR/SR comment, it can be done in accordance with 8.3.3.5 '16. This has saved me on a couple of projects with EC sprinklers.

Reply
Franck Orset
2/19/2019 11:06:26 am

Mixing K-factor is not a good idea, unless you have good reasons for it (such as a deluge system where the K factor may different depending on the area for the entire surface coverage, but this is not a sprinkler system...).
Mixing different temperatures can be deemed necessary because of possible change of local room temperature (sprinkler heads next to a heater, below a skylight...).
In the 2019 Edition, the chapter is now 9.4.2 (& 9.4.2.5 for a list of examples), and not 8.3.2 (& 8.3.2.5).
You could mix K-factor in the same room (as well as T° rating) if you have a change of occupancy that would require this particular change.
For example, if you have a processing area (let's say OH Gr 1 activity with ordinary rated temperature sprinkler heads), but a dedicated storage area representing a higher fire challenge (a few racks, or a idle pallets storage). In that case, you might need to have larger orifice sprinkler heads and/or higher temperature rated sprinkler heads.
But there are rules, as indicated above, because you will need to extend the most demanding area beyond the area of protection (or provide a draft curtain/fire barrier).
This is part of chapter 20.10 of NFPA 13 (2019 Edition) : Adjacent hazards or design methods.

Reply
tyrone loukas link
7/28/2024 04:30:01 am

Thank you for the insightful information on mixing K-factors and temperatures in the same room! Your detailed explanation helps clarify how these factors interact and the impact they can have on room conditions. I appreciate the practical advice and the way you’ve made a complex topic more understandable. Your guidance is invaluable for optimizing room environments and ensuring accurate measurements. Thanks for your expertise!

Reply



Leave a Reply.

    SUBMIT A QUESTION
    Picture
    Why Sponsor?

    ALL-ACCESS

    Picture
    GET ALL OUR TOOLS

    SUBSCRIBE

    Subscribe and learn something new each day:
    I'm Interested In:

    COMMUNITY

    Top June '25 Contributors
    Picture
    Picture
    Picture
    Picture
    Picture
    Picture
    Picture
    Picture
    Picture
    Picture
    SEE LEADERBOARD

    YOUR POST

    SUBMIT A QUESTION

    PE EXAM

    Get 100 Days of Free Sample Questions right to you!
    SIGN ME UP!

    FILTERS

    All
    A1171
    ABA
    ADA
    ASCE 7
    ASME A17.1
    ASTM E1354
    Blog Thread
    Daily Discussion
    Design-documents
    EN 12845
    Explosion Protection
    Explosion-protection-prevention
    Fire Detection And Alarm Systems
    Fire Dynamics
    Flammable And Combustible Liquids
    Flammable-combustible-liquids
    FM Global
    Human-behavior
    IBC
    ICC 500
    IEBC
    IFC
    IMC
    IPC
    IRC
    ISO
    Means Of Egress
    NBC
    NFPA 1
    NFPA 10
    NFPA 101
    NFPA 11
    NFPA 110
    NFPA 1142
    NFPA 1221
    NFPA 13
    NFPA 13D
    NFPA 13R
    NFPA 14
    NFPA 15
    NFPA 16
    NFPA 17A
    NFPA 20
    NFPA 2001
    NFPA 214
    NFPA 22
    NFPA 220
    NFPA 24
    NFPA 241
    NFPA 25
    NFPA 291
    NFPA 30
    NFPA 307
    NFPA 30B
    NFPA 31
    NFPA 33
    NFPA 37
    NFPA 400
    NFPA 409
    NFPA 415
    NFPA 45
    NFPA 495
    NFPA 497
    NFPA 5000
    NFPA 502
    NFPA 54
    NFPA 55
    NFPA 654
    NFPA 68
    NFPA 70
    NFPA 701
    NFPA 72
    NFPA 75
    NFPA 770
    NFPA 82
    NFPA 850
    NFPA 855
    NFPA 90A
    NFPA 92
    NFPA 96
    NICET
    OBC
    OSHA
    Passive Building Systems
    PE Prep Guide
    PE Prep Series
    PE Sample Problems
    Poll
    Smoke Management
    Special Hazard Systems
    UFC 3-600-01
    UFC 4-021-01
    UFC 4-211-01
    UPC
    Updates
    Water Based Fire Suppression
    Weekly Exams


    ARCHIVES

    July 2025
    June 2025
    May 2025
    April 2025
    March 2025
    February 2025
    January 2025
    December 2024
    November 2024
    October 2024
    September 2024
    August 2024
    July 2024
    June 2024
    May 2024
    April 2024
    March 2024
    February 2024
    January 2024
    December 2023
    November 2023
    October 2023
    September 2023
    August 2023
    July 2023
    June 2023
    May 2023
    April 2023
    March 2023
    February 2023
    January 2023
    December 2022
    November 2022
    October 2022
    September 2022
    August 2022
    July 2022
    June 2022
    May 2022
    April 2022
    March 2022
    February 2022
    January 2022
    December 2021
    November 2021
    October 2021
    September 2021
    August 2021
    July 2021
    June 2021
    May 2021
    April 2021
    March 2021
    February 2021
    January 2021
    December 2020
    November 2020
    October 2020
    September 2020
    August 2020
    July 2020
    June 2020
    May 2020
    April 2020
    March 2020
    February 2020
    January 2020
    December 2019
    November 2019
    October 2019
    September 2019
    August 2019
    July 2019
    June 2019
    May 2019
    April 2019
    March 2019
    February 2019
    January 2019
    December 2018
    November 2018
    October 2018
    September 2018
    August 2018
    July 2018
    June 2018
    May 2018
    November 2017
    October 2017
    September 2017
    August 2017
    July 2017
    June 2017
    November 2016
    October 2016
    July 2016
    June 2016


    PE PREP SERIES

    SEE LEADERBOARD

    RSS Feed

Picture
​Home
Our Cause
The Blog
The Forum
PE Exam Prep
The Toolkit

MeyerFire University
​Pricing
Login
​Support
Contact Us
Picture

MeyerFire.com is a startup community built to help fire protection professionals shine.
Our goal is to improve fire protection practices worldwide. We promote the industry by creating helpful tools and resources, and by bringing together industry professionals to share their expertise.

​MeyerFire, LLC is a NICET Recognized Training Provider and International Code Council Preferred Education Provider.

All text, images, and media ​Copyright © 2016-2025 MeyerFire, LLC

We respect your privacy and personal data. See our Privacy Policy and Terms of Service. 
The views, opinions, and information found on this site represent solely the author and do not represent the opinions of any other party, nor does the presented material assume responsibility for its use. Fire protection and life safety systems constitute a critical component for public health and safety and you should consult with a licensed professional for proper design and code adherence.

Discussions are solely for the purpose of peer review and the exchange of ideas. All comments are reviewed. Comments which do not contribute, are not relevant, are spam, or are disrespectful in nature may be removed. Information presented and opinions expressed should not be relied upon as a replacement for consulting services. Some (not all) outbound links on this website, such as Amazon links, are affiliate-based where we receive a small commission for orders placed elsewhere.

  • Blog
  • Forum
  • TOOLKIT
    • ALL TOOLS
    • BUY THE TOOLKIT
  • UNIVERSITY
    • ALL COURSES
    • JOIN THE UNIVERSITY
  • PE Exam
    • PE Forum & Errata
    • PE Store
    • PE Tools
    • PE PREP SERIES
    • PE 100-Day Marathon
  • LOGIN
    • TOOLKIT-ONLY LOGIN
    • UNIVERSITY LOGIN
  • PRICING
    • SOFTWARE & TRAINING
    • STORE
  • OUR CAUSE
    • ABOUT MEYERFIRE
    • JOB OPENINGS
    • BECOME AN INSTRUCTOR
    • HELP/SUPPORT