MeyerFire
  • Blog
  • Forum
  • THE TOOLKIT
    • SUBMIT AN IDEA
    • BACKFLOW DATABASE*
    • CLEAN AGENT ESTIMATOR*
    • CLOUD CEILING CALCULATOR
    • DOMESTIC DEMAND*
    • FIRE FLOW CALCULATOR*
    • FIRE PUMP ANALYZER*
    • FIRE PUMP DATABASE*
    • FRICTION LOSS CALCULATOR
    • HANGER SPACER*
    • IBC TRANSLATOR*
    • K-FACTOR SELECTOR*
    • NFPA 13 EDITION TRANSLATOR ('19 ONLY)
    • NFPA 13 EDITION TRANSLATOR ('99-'22)*
    • LIQUIDS ANALYZER*
    • OBSTRUCTION CALCULATOR
    • OBSTRUCTIONS AGAINST WALL*
    • PLUMBING FIXTURE COUNTS
    • QUICK RESPONSE AREA REDUCTION
    • REMOTE AREA ANALYZER*
    • SPRINKLER DATABASE*
    • SPRINKLER FLOW*
    • SYSTEM ESTIMATOR*
    • TEST & DRAIN CALCULATOR
    • THRUST BLOCK CALCULATOR
    • TRAPEZE CALCULATOR
    • UNIT CONVERTER
    • VOLUME & COMPRESSOR CALCULATOR
    • WATER STORAGE*
    • WATER SUPPLY (US)
    • WATER SUPPLY (METRIC)
  • UNIVERSITY
    • About
    • Catalog
    • CONTENT LIBRARY
  • PE Exam
    • PE Forum & Errata
    • PE Store
    • PE Tools
    • PE Prep Series
    • PE 100-Day Marathon
  • LOGIN
  • PRICING
    • SOFTWARE & TRAINING
    • STORE
  • THE CAUSE
    • ABOUT US
    • BECOME AN INSTRUCTOR
    • HELP/SUPPORT
Picture

Coefficient of Discharge for Forward-Flow in FDC?

10/5/2021

6 Comments

 
In my area many designers use the main test/drain or one of the FDC inlets to conduct forward flow for the double check backflow assembly. They use the velocity pressure pitot equation to demonstrate that they will achieve the system demand flow. During the acceptance testing, I verify that the system demand is achieved by measuring with a pitot gauge and calculating the flow.

I generally use a coefficient of 1 when a hose monster or the main drain piping is flowed from, because they are long runs of smooth continuous pipe.

Is this appropriate or should I be using some other coefficient?

​​​​​​​​​​​​​​​​​​​​​​​Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe
6 Comments
Alex
10/5/2021 05:18:25 am

Hi Anonymous,

When using any Hose Monster device, their coefficients are published online. Link below.

Link: https://hosemonster.com/wp-content/uploads/2021/09/HYDRAULICS-ENGINEERING-INFORMATION.pdf

Thanks,
Alex

Reply
Jesse
10/5/2021 08:10:27 am

If its a Hose Monster branded device, they have coefficient data on their website.

If we're using "hose monster" in a ubiquitous / generic way like "coke" or Kleenex" the hydraulic data should be on the actual manufacturers website.

If its a home made hose monster type device, then I don't really know.

Reply
Cordell
10/5/2021 08:30:11 am

In many instances the 2" main drain or a single 2-1/2" outlet will not achieve the desired flow rate. I have added a manifold with six 2-1/2" outlets to achieve the system flow. To answer your question regarding the outlet coefficient, a coefficient of 1 would not be suitable since this is not a smooth outlet. 0.9 or 0.8 would be a better option.

Reply
Randy Kimbro link
10/5/2021 10:38:56 am

As an AHJ, I agree with Cordell. The 2" main drain or a single 2-1/2" outlet will not achieve the desired flow rate. We require the installation of one to many 2-1/2" outlets to achieve the system flow.

As an aside, starting with the 2019 version of NFPA 13, there is a requirement that the riser be permanently plumbed for forward flow. 16.14.5 ".. shall be serviceable without requiring the owner to modify the system to perform the test".

There is also an exception that says where connections do not permit full flow you can conduct the test "at the maximum flow rate possible". NFPA 25 13.7.2.3. Again as an AHJ it is rare that a riser cannot be altered to add outlets for this required annual test.

Reply
sean
10/5/2021 07:08:32 pm

i think the main issue is 1 is a super efficient delivery a play pipe does not achieve that and it is significantly smoother and las more laminar flow a .9 is the max I would personally find acceptable.

Reply
Dan Wilder
10/6/2021 09:04:33 am

I recently had an AHJ redline a plan for this reason.

We use a 4" Hose Monster for all of our flow tests with calibrated gauges with results coming from the gauge/chart (the coefficient comes out different based on the pitot/flow when using the formula. in my case it resulted in a just below .8) . The AHJ said that their hydrants were all a .9 in that area and that our flow test was invalid.

We ended up getting a letter from Hose Monster Techs with a great explanation that the point of the flow where the pitot tube was taking measurements became the effective point for the coefficient, i.e. the equipment itself not the internals of the hydrant. Had we used a pitot on the hydrant itself the .9 would be accurate but as we used a remote piece of equipment that their charts became the approved result (regardless of coefficient).

Even if you are using pipe, NFPA 291-19' Section 4.7.2 suggests a C of .95 or as others have suggested use the MFG data sheets indicating the effective C.

Reply



Leave a Reply.

    Picture
    Why Sponsor?

    ALL-ACCESS

    Picture
    GET ALL OUR TOOLS

    SUBSCRIBE

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

    COMMUNITY

    Top ​Jan 2023 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
    A117.1
    ABA
    ADA
    ASCE 7
    ASME A17.1
    ASTM E1354
    Daily Discussion
    Design Documents
    EN 12845
    Explosion Protection & Prevention
    Fire Detection And Alarm Systems
    Fire Dynamics
    Flammable & Combustible LIquids
    FM Global
    Human Behavior
    IBC
    ICC-500
    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 33
    NFPA 400
    NFPA 409
    NFPA 415
    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 82
    NFPA 855
    NFPA 90A
    NFPA 92
    NFPA 96
    NICET
    OBC
    Passive Building Systems
    PE Prep Guide
    PE Prep Series
    PE Sample Problems
    Poll
    Smoke Management
    Special Hazard Systems
    UFC 3 600 01
    UFC 3-600-01
    UFC 4-021-01
    Updates
    Water Based Fire Suppression
    Weekly Exams


    ARCHIVES

    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

    Fire Protection PE Exam Prep
    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 an International Code Council Preferred Education Provider.

All text, images, and media ​Copyright © 2023 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
  • THE TOOLKIT
    • SUBMIT AN IDEA
    • BACKFLOW DATABASE*
    • CLEAN AGENT ESTIMATOR*
    • CLOUD CEILING CALCULATOR
    • DOMESTIC DEMAND*
    • FIRE FLOW CALCULATOR*
    • FIRE PUMP ANALYZER*
    • FIRE PUMP DATABASE*
    • FRICTION LOSS CALCULATOR
    • HANGER SPACER*
    • IBC TRANSLATOR*
    • K-FACTOR SELECTOR*
    • NFPA 13 EDITION TRANSLATOR ('19 ONLY)
    • NFPA 13 EDITION TRANSLATOR ('99-'22)*
    • LIQUIDS ANALYZER*
    • OBSTRUCTION CALCULATOR
    • OBSTRUCTIONS AGAINST WALL*
    • PLUMBING FIXTURE COUNTS
    • QUICK RESPONSE AREA REDUCTION
    • REMOTE AREA ANALYZER*
    • SPRINKLER DATABASE*
    • SPRINKLER FLOW*
    • SYSTEM ESTIMATOR*
    • TEST & DRAIN CALCULATOR
    • THRUST BLOCK CALCULATOR
    • TRAPEZE CALCULATOR
    • UNIT CONVERTER
    • VOLUME & COMPRESSOR CALCULATOR
    • WATER STORAGE*
    • WATER SUPPLY (US)
    • WATER SUPPLY (METRIC)
  • UNIVERSITY
    • About
    • Catalog
    • CONTENT LIBRARY
  • PE Exam
    • PE Forum & Errata
    • PE Store
    • PE Tools
    • PE Prep Series
    • PE 100-Day Marathon
  • LOGIN
  • PRICING
    • SOFTWARE & TRAINING
    • STORE
  • THE CAUSE
    • ABOUT US
    • BECOME AN INSTRUCTOR
    • HELP/SUPPORT