MeyerFire
  • Blog
  • Daily
  • Exam Prep
    • CFPS Tools
    • NICET Tools
    • PE Forum & Errata
    • PE Problems
    • PE Store
    • PE Tools
    • PE Prep Series
  • TOOLS
    • TOOLKIT (FREE TRIAL)
    • *TOOLKIT (PURCHASE)
    • SUBMIT AN IDEA
    • BACKFLOW DATABASE*
    • CLEAN AGENT ESTIMATOR
    • CLOUD CEILING CALCULATOR
    • DOMESTIC DEMAND
    • FIRE PUMP ANALYZER
    • FIRE PUMP DATABASE*
    • FIRE FLOW CALCULATOR*
    • FRICTION LOSS CALCULATOR
    • HANGER SPACER
    • IBC TRANSLATOR*
    • K-FACTOR SELECTOR
    • NFPA 13 EDITION TRANSLATOR ('19 ONLY)
    • NFPA 13 EDITION TRANSLATOR ('99-'19)*
    • LIQUIDS ANALYZER*
    • OBSTRUCTION CALCULATOR
    • OBSTRUCTIONS AGAINST WALL*
    • PLUMBING FIXTURE COUNTS
    • REMOTE AREA ANALYZER
    • QUICK RESPONSE AREA REDUCTION
    • SPRINKLER DATABASE*
    • SPRINKLER FLOW*
    • TEST & DRAIN CALCULATOR
    • THRUST BLOCK CALCULATOR
    • TRAPEZE CALCULATOR
    • UNIT CONVERTER
    • VOLUME & COMPRESSOR CALCULATOR
    • WATER SUPPLY (US)
    • WATER SUPPLY (METRIC)
  • CODE CALLS
  • LOGIN
  • STORE
  • About
Picture
A FORUM FOR FIRE PROTECTION QUESTIONS & PE EXAM PROBLEMS | SUBSCRIBE NOW

Is Pitot the Same As Residual on Flow Test?

12/27/2019

5 Comments

 
Fire hydrant flow test question - is the pitot the same as the residual pressure on a water flow test from a fire hydrant?

Is it possible to know the residual pressure and 'chart out' the flow of the fire hydrant, or is there a way to determine the flow with only the static and residual pressures?

​​​Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe
5 Comments
Mike L
12/27/2019 08:09:36 am

Pitot Pressure and Residual Pressure are two separate measurements. Pitot pressure is used to calculate the flow rate from the hydrant that correlates to the residual pressure being read.

The values of Static Pressure (no flow) and residual pressure (at the calculated flow rate) are then plotted on a graph to produce the water supply curve.

Please read NFPA-291 for Hydrant Flow Test procedures and resultant calculations.

Reply
Wayne Ammons
12/27/2019 09:17:05 am

To add to what Mike said, you can conduct a flow test if you do not have a pitot tube:

NFPA 291, 2016 Edition:

4.9 Determination of Discharge Without a Pitot.

4.9.1 If a pitot tube is not available for use to measure the hydrant discharge, a 50 or 60 psi (3.4 or 4.1 bar) gauge tapped
into a hydrant cap can be used.

4.9.2 The hydrant cap with gauge attached is placed on one outlet, and the flow is allowed to take place through the other outlet at the same elevation.

4.9.3 The readings obtained from a gauge so located, and the readings obtained from a gauge on a pitot tube held in the stream, are approximately the same.

Reply
joe
12/28/2019 02:26:17 pm

What do you do if the city fire don't have a residual for a preliminary calculation on a bid? some cities i deal with only have static and pitot it is not smart to drive 2 hours one-way for to make flow test on a job you may not get. i just trying to figure out a way to get a residual what the city doesn't have a residual pressure.

Joe Meyer
12/30/2019 07:41:29 am

We don't have flow test information for many bids we go after. It's extremely annoying and not helpful to the project.

If we are calculating a system we will generally have some idea of what the area can handle from a water-supply perspective.

If an area is very hilly, I will check the elevation of the project compared to nearby projects I've completed or the elevation compared to the nearest water tower. I've been able to estimate water supplies using this method too.

Ultimately, you may consider protecting your bid by qualifying it with an assumed water supply - if the job actually requires a fire pump then provide an alternate price for it. Most projects for us are generally pretty straight-forward as to whether it would need a pump or not based on the building's height and hazard.

Mike L
12/30/2019 02:43:49 pm

1 more thought...I believe that in order for a water supply to be considered a municipal supply, it must be able to deliver a minimum of 20 psi residual. So you could use that as a basis to develop your bid/pump requirement. I would qualify the bid stating that absent of verified residual pressure an assumption of 20 psi was assumed.

Reply



Leave a Reply.

    Jump to: Daily Posts
    Jump to: PE Problems
    Picture
    Why Sponsor?

    Free Signup

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

    Community

    Thank You to Our Top
    ​October '20 Contributors!
    1. SK
    2. Franck
    3. Dan W.
    4. Jonathan ​5. Casey M.
    6. Sean
    7. Colin L.
    8. Mike
    9. Jonathan J
    ​10. Daniel G.


    Your Post

    SUBMIT A QUESTION

    The Toolkit

    Sprinkler Designer or Engineer?
    ​
    ​Get all of our tools, including the Sprinkler Database, Friction Loss Calculator, Fire Pump Analyzer and more:
    Picture
    FREE 30-DAY TRIAL
    GET THE TOOLKIT

    Filters

    All
    ABA
    ADA
    ASCE 7
    ASME A17.1
    Daily Discussion
    Design Documents
    Explosion Protection & Prevention
    Fire Detection And Alarm Systems
    Fire Dynamics
    Flammable & Combustible LIquids
    FM Global
    Human Behavior
    IBC
    IFC
    Information Sources For Analysis
    IRC
    Means Of Egress
    NFPA 1
    NFPA 10
    NFPA 101
    NFPA 11
    NFPA 110
    NFPA 12
    NFPA 13
    NFPA 13D
    NFPA 13R
    NFPA 14
    NFPA 15
    NFPA 17A
    NFPA 20
    NFPA 2001
    NFPA 214
    NFPA 22
    NFPA 24
    NFPA 25
    NFPA 291
    NFPA 30
    NFPA 400
    NFPA 415
    NFPA 497
    NFPA 5000
    NFPA 502
    NFPA 54
    NFPA 70
    NFPA 72
    NFPA 92
    NICET
    Passive Building Systems
    PE Prep Guide
    PE Prep Series
    PE Sample Problems
    Poll
    Smoke Management Systems
    Special Hazard Systems
    Types Of Analysis
    UFC 3 600 01
    UFC 3-600-01
    Updates
    Water Based Fire Suppression
    Weekly Exams


    Archives

    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
    June 2015


    Daily
    Daily discussions are open-ended fire protection, fire alarm, and life safety questions submitted anonymously for the benefit of sharing expertise and learning from other perspectives. Anyone can submit a question here:
    SUBMIT A QUESTION

    Exam Prep

    Picture
    2020 PE Prep Guide​
    ​(Available Now!)
    Picture
    PE Prep Series
    ​(Available Now!)
    2020 PE Prep Series
    Current Leaderboard
    ​(Click to enlarge)
    Fire Protection PE Exam Prep

    PE Problems
    ​Visit July-October for daily Fire Protection PE Exam sample questions.

    Solutions are posted the day after posting.

    Comment with your solutions, questions or clarifications.

    Please note that questions posted are unofficial and in accordance with NCEES rules are intended to be similar to actual exam questions, not actual exam questions themselves.

    RSS Feed

Home - About - Blog - Contact - Exam Prep - Store
Picture
Copyright © 2020 MeyerFire, LLC
The views, opinions, and information found on this site represent solely the author shown 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. Some (not all) outbound links on this website, such as Amazon links, are affiliate-based where we receive a commission for orders placed elsewhere.
  • Blog
  • Daily
  • Exam Prep
    • CFPS Tools
    • NICET Tools
    • PE Forum & Errata
    • PE Problems
    • PE Store
    • PE Tools
    • PE Prep Series
  • TOOLS
    • TOOLKIT (FREE TRIAL)
    • *TOOLKIT (PURCHASE)
    • SUBMIT AN IDEA
    • BACKFLOW DATABASE*
    • CLEAN AGENT ESTIMATOR
    • CLOUD CEILING CALCULATOR
    • DOMESTIC DEMAND
    • FIRE PUMP ANALYZER
    • FIRE PUMP DATABASE*
    • FIRE FLOW CALCULATOR*
    • FRICTION LOSS CALCULATOR
    • HANGER SPACER
    • IBC TRANSLATOR*
    • K-FACTOR SELECTOR
    • NFPA 13 EDITION TRANSLATOR ('19 ONLY)
    • NFPA 13 EDITION TRANSLATOR ('99-'19)*
    • LIQUIDS ANALYZER*
    • OBSTRUCTION CALCULATOR
    • OBSTRUCTIONS AGAINST WALL*
    • PLUMBING FIXTURE COUNTS
    • REMOTE AREA ANALYZER
    • QUICK RESPONSE AREA REDUCTION
    • SPRINKLER DATABASE*
    • SPRINKLER FLOW*
    • TEST & DRAIN CALCULATOR
    • THRUST BLOCK CALCULATOR
    • TRAPEZE CALCULATOR
    • UNIT CONVERTER
    • VOLUME & COMPRESSOR CALCULATOR
    • WATER SUPPLY (US)
    • WATER SUPPLY (METRIC)
  • CODE CALLS
  • LOGIN
  • STORE
  • About