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

Fire Pump Start/Stopping with Jockey Idle?

9/20/2021

8 Comments

 
To me, it makes more sense to locate a backflow on the suction side of a pump. However, I have recently run across a facility with the backflow downstream of the pump (discharge side).

The main fire pump controller is connected between the the first check valve and the backflow preventer.

The jockey pump is connected after the backflow preventer.

Here's the problem: when the first check valve fails, the main fire pump continuously starts & stops because the pressure is bleeding off they the relief valve while the jockey pump remains idle.

Is this an acceptable scenario?

​​​​​​​​​​​​​​​​​​​​​​​Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe
8 Comments
Glenn Berger
9/20/2021 08:35:05 am

1) the installation of the BFP after the fire pump is not that unusual. It is easier to account for the pressure loss with the pump. Locating the BFP before the pump does create potential scenarios for low suction pressure.

2) The sensing lines for the jockey pump and the fire pump MUST be in the same general location. Need to examine the pump discharge check valve to see why pressure is not being maintained.

Reply
Jesse
9/20/2021 08:46:25 am

Agree with Glenn. Though its not my favorite, there are reasons sometimes to put the BFP downstream of the pump. Usually these have to do with the increased friction loss the BFP creates when the pump is at 150%.

Reply
Ed Glynn link
9/20/2021 10:12:49 am

We have installed backflows in a similar fashion as there are inherent issues with low suction potentially.

It is our experience that both sensing lines for the pump and the jockey pump need to be down stream of the back flow because the shorter piece of pipe in-between the check valve and the back flow tens to hold pressure much longer than down stream of the back flow.

Putting it down stream allows for a more accurate reflection of the pressure down stream.

Reply
Alex
9/20/2021 10:34:22 am

Hi Anonymous,

NFPA 20 (2019) Figure A.6.3.1(b) shows the backflow installed on the pump discharge. I typically design this way so I can accurately account for the friction loss.

I agree with Glenn that it is important to have the sensing lines in the same general location. Having them installed within the same vicinity allows for the sensing lines to be more in line with each other. In your case, the jockey pump could then take over rather than starting your pump.

Thanks,
Alex

Reply
Mike
9/20/2021 10:36:26 am

Have you tried raising the sensing line pressure start? May be too low.

Reply
Franck
9/20/2021 11:28:38 am

Are you speaking of a booster pump ?

In the case of a fire pump taking suction from a tank, you should not have a problem (and normally no need for a backflow preventer in addition to the check valve).
The reason for a check valve is to avoid, if you have several pumps in a parallel arrangement, that the pump that is operating can flow water to the other one that would then turn in the opposite direction. With an electric drive, this may destroy the motor.

In the case of a booster pump, it may make sense to have the backflow preventer (to avoid pollution in the city water supply) upstream the pump. But at a sufficient distance (normally 50 ft) to avoid water flow disturbance at the intake (creating cavitation, turbulences and early aging of the impeller / pump casing)

I do not understand your start and stop sequencing for the main pump as it should start automatically and stop only manually

in all case, if your pump starts because of a defect on the check valve, this would be an indication that you need to repair it and you need to know it.

Reply
Franck
9/20/2021 12:47:42 pm

In all cases, as indicated by other peers, it makes sense to have the sensing lines connected on the same side of the check valve / backflow preventer

The pressure reading from the Jockey pump should be the same as for the fire pump(s).

And this would prevent the fire pump to start instead of the Jockey pump

Reply
Dale
9/21/2021 12:45:00 pm

This is an existing condition, so this is not exactly applicable, but I was told that it's better to have the BFP in front of the pump, as the BFP may not be rated for the higher pressure created by the Fire Pump. Just some food for thought.

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 ​July '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 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 497
    NFPA 5000
    NFPA 502
    NFPA 54
    NFPA 55
    NFPA 654
    NFPA 68
    NFPA 70
    NFPA 72
    NFPA 75
    NFPA 82
    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
    UFC 4-021-01
    Updates
    Water Based Fire Suppression
    Weekly Exams


    ARCHIVES

    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 © 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.

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