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

Backflow Allowed Before Fire Pump Suction?

2/1/2021

8 Comments

 
We have a building with a double check backflow assembly on the suction side of a fire pump. Normally there is a minimum of 10 pipe diameters of vertical plane pipe just before the suction flange.

Is the double check backflow allowed within that distance?

Are there requirements for the backflow to have flanges vs. grooved connections?

A colleague said the control valve should be OS&Y rather than butterfly on the suction side only. Why would this be the case? I would assume the OS&Y would reduce turbulence better than a butterfly, but wouldn't the checks also cause turbulence?

Thanks in advance.

​​​Sent in anonymously for discussion. Discuss This | Submit Your Question | Subscribe
8 Comments
Brian Gerdwagen FPE
2/1/2021 09:20:50 am

Control valves on the suction side of the pump should always be OS&Y per NFPA 20.

There is no requirement for grooved versus flanged connections as long as the pressure ratings are acceptable for the application. Regular grooved fittings are fine for the suction side.

Backflows can be on the suction side, but you are correct, it is good practice to keep them farther away from the pump than directly connected to the suction flange.

Reply
Jesse
2/1/2021 09:28:42 am

Backflow preventers can be on the suction side, keeping in mind OS&Y Valve requirements, etc.

Some AHJs require them on the suction side, as they consider the pump to be a contaminate source. NFPA 20 nd testing does a pretty good job dispelling this.

The only concern I'd have is ensuring the hydraulic hit we take in friction loss through the BFP doesn't create a problem with available pressure at the suction inlet. If your latent water supply is sketchy with low pressures, that may be a problem.

Reply
Dan Wilder
2/1/2021 09:25:03 am

Well, couple of Q's and some A's for ya....

Yes, you can have a backflow on the suction side of the pump and as long as it's allowing the 10 pipe diameters requirement, it is acceptable*. Grooved or Flanged makes no difference, the internal flow disruption from the vane is the issue as you pointed out.

*I say acceptable because the backflow would require OS&Y's, if you were to have butterfly valves the distance (overall) increases to 50' (20-19' - Section 4.16.5.4).

One issue with backflow on the suction side occurs when the pump is tested to 150% as many backflows are not listed at the higher GPM (Rated Flow) and can cause failure of the device.

Reply
CJ Bonczyk
2/1/2021 09:37:26 am

NFPA 20 prefers BFP's/RPZ's on the discharge side of the booster pump. However many jurisdictions such as ours require the BFP on the suction side. If the device is on the suction side the following rules apply:

1. Devices must be installed per NFPA 20 4.29
2. The device (BFP) must be a minimum of 10 pipe diameters to the suction flange of the pump (with the installation of a OS&Y type BFP).
3. If the BFP has butterfly control valves the BFP is required to be at least 50 feet from the pump suction flange measured along the route of the pipe in accordance with 4.16.5.4.

*Both types of BFP's will have check assemblies, however, OS&Y's are the preferred type of valve as they cause less turbulence than a butterfly style valve.*

5. Pay attention ti the increased suction pressure loss from the BFP when sizing the pump based off the system demand.
6. When a BFP is installed the final arrangement shall provide effective pump performance at the lowest permissible suction pressure.
7. ***The discharge flow rate shall meet or exceed the fire protection system design flow.***
8. The discharge flow rate shall meet or exceed 100% of the fire pump rated flow rate.
9. Determination of effective pump performance is to be documented by engineering calculations and tests.

Pay attention to any retroactive BFP installations on the suction side of a booster pump as outlined in 4.29.4.1.6 & 4.29.4.1.7

Lastly pay close attention to the technical performance & installation data for the BFP itself, and ensure you have enough space for clearance and removal. I would personally recommend to add a bypass meter on the BFP even if not required by the local waterworks authority.

Reply
Mike
2/1/2021 09:51:31 am

Devices allowed in the suction piping and installation requirements are shown in section 4.15 Suction Pipe and Fittings of NFPA 20, 2016 if you have anymore questions.

Reply
Stephen L Aikey
2/1/2021 11:39:38 am

As usual there are great comments. I would like to highlight the BFP technical performance & installation data portion of this discussion.

Most who do this for a living are aware of the friction loss requirements we input into our hydraulic programs for this application to ensure the design is acceptable.

However, I want to point out the BFP check valve spring tension requirements. Have not seen anyone bring this up.

The minimum upstream water supply pressure required to open the internal check valve springs which are under spring tension.

Some BFP Manufactures have high flow / low pressure drop BFP's that are great for hydraulic calculated designs. That being said, you should be aware it may take at least 16 psi. to open the internal check valves.

Also note some Manufactures post that data on their data sheets. And some do not!

The BFP spring tension information is very important when working with water supply tanks and or low pressure city mains.

Reply
Dale
2/8/2021 09:27:06 am

I was always instructed by my fellow well experienced Engineers to install the backflow on the suction side, as the backflow may not be listed for the now increased system pressure that the Fire Pump is providing.

Reply
Gear Pumps link
2/13/2021 07:03:53 am

Thank you very much for sharing about backflow allowed before fire pump suction here… I really hope I can work on your tips and it works for me too, I am happy to come across your article. Great post I must admit, keep sharing more…

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 ​April '22 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
    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
    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 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 497
    NFPA 5000
    NFPA 502
    NFPA 54
    NFPA 55
    NFPA 654
    NFPA 68
    NFPA 70
    NFPA 72
    NFPA 75
    NFPA 90A
    NFPA 92
    NICET
    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
    Updates
    Water Based Fire Suppression
    Weekly Exams


    ARCHIVES

    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 © 2022 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. The discussions are solely for the purpose of peer review and the exchange of ideas. 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