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  • 1.  Water Flow Rate Requirement

    Posted 04-10-2024 21:16
    Edited by Lars Larson 04-11-2024 13:36

    Fellow ATB Colleagues,

    I have a friend who is opening a taproom brewery with a kitchen who asked me to look over his water flow rate needs.  My suggested approach was to determine the total flow requirement for all sinks and toilets in the public area and kitchen.  He collected this information and it comes up to 70 gpm.  For the brewery, I suggested looking at a worst case water demand based on rinsing two 10 BBL tanks simultaneously and using his keg cleaner.  The total of these flows is 65 gpm.  He will have a hot water and cold water tank, where the cold water tank is being filled through an RO system running at 5 gpm.  His total worst-case estimate is 140 gpm.

    The brewhouse is 10 BBLs and he will have (4) 10 BBL fermenters, (8) 10 BBL lagering tanks, and (1) 10 BBL bright beer tank.  His customer space + kitchen is about 2000 square feet.  Based on the total flow rate required, it appears that the 1.5" water line feeding the building is sufficient (sprinklers are on a separate line).  Increasing the water main size is an option, but is expensive.

    Does anyone out there running a similarly sized facility have any comparable figures to share?

    Cheers,

    Ashton



    ------------------------------
    Ashton Lewis
    Manager of Training and Technical Support
    BSG Craftbrewing
    MBAA District Great Plains, Technical Chair
    Springfield, Missouri
    (417) 830-2337
    ------------------------------



  • 2.  RE: Water Flow Rate Requirement

    Posted 04-11-2024 12:46

    What pressure do you have coming in from the city, in that 1.5" line?



    ------------------------------
    Craig Murphy | Plant Manager
    Jack's Abby Craft Lagers, Framingham MA
    (857) 231-1356
    craigm@jacksabby.com
    ------------------------------



  • 3.  RE: Water Flow Rate Requirement

    Posted 04-11-2024 14:24

    Hi Craig, they have 40 psig coming into the building.



    ------------------------------
    Ashton Lewis
    Manager of Training and Technical Support
    BSG Craftbrewing
    MBAA District Great Plains, Technical Chair
    Springfield, Missouri
    (417) 830-2337
    ------------------------------



  • 4.  RE: Water Flow Rate Requirement

    Posted 04-11-2024 17:35

    I did some math with a few online calculators, and I'm getting varied results:

    "40PSI at 1.5" = 110 GPM maximum capacity"

    (https://resources.hy-techroof.com/blog/how-much-water-can-flow-through-a-pipe)

    ChatGPT spit out this gem:

    To determine the flow rate in gallons per minute (GPM), we need to solve for the flow velocity (<math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>V</mi></mrow></semantics></math>) using the Darcy-Weisbach equation and then use the cross-sectional area of the pipe to calculate the flow rate.

    Given the parameters provided:

    • Equivalent length of the pipe (<math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>L</mi></mrow></semantics></math>): 220 feet
    • Pipe diameter (<math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>D</mi></mrow></semantics></math>): 0.125 feet (1.5 inches)
    • Density of water (<math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>ρ</mi></mrow></semantics></math>): 62.4 lb/ft³
    • Darcy friction factor (<math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>f</mi></mrow></semantics></math>): 0.02 (assumed)
    • Pressure drop (<math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi mathvariant="normal">Δ</mi><mi>P</mi></mrow></semantics></math>) from 40 PSI to atmospheric pressure: 40 PSI - 14.7 PSI = 25.3 PSI

    Now, let's plug these values into the Darcy-Weisbach equation to find the flow velocity (<math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>V</mi></mrow></semantics></math>):

    <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>V</mi><mo>=</mo><msqrt><mfrac><mrow><mn>2</mn><mo>×</mo><mi mathvariant="normal">Δ</mi><mi>P</mi><mo>×</mo><mi>D</mi></mrow><mrow><mi>f</mi><mo>×</mo><mi>L</mi><mo>×</mo><mi>ρ</mi></mrow></mfrac></msqrt></mrow></semantics></math>

    <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>V</mi><mo>=</mo><msqrt><mfrac><mrow><mn>2</mn><mo>×</mo><mn>25.3</mn><mo>×</mo><mn>0.125</mn></mrow><mrow><mn>0.02</mn><mo>×</mo><mn>220</mn><mo>×</mo><mn>62.4</mn></mrow></mfrac></msqrt></mrow></semantics></math>

    <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>V</mi><mo>≈</mo><msqrt><mfrac><mn>6.325</mn><mn>27.456</mn></mfrac></msqrt></mrow></semantics></math>

    <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>V</mi><mo>≈</mo><msqrt><mn>0.23</mn></msqrt></mrow></semantics></math>

    <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>V</mi><mo>≈</mo><mn>0.479</mn><mtext> </mtext><mtext>ft/s</mtext></mrow></semantics></math>

    Now, we can calculate the flow rate (<math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>Q</mi></mrow></semantics></math>) using the formula:

    <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>Q</mi><mo>=</mo><mi>A</mi><mo>×</mo><mi>V</mi></mrow></semantics></math>

    Where <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>A</mi></mrow></semantics></math> is the cross-sectional area of the pipe. The cross-sectional area of a pipe with diameter <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>D</mi></mrow></semantics></math> is:

    <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>A</mi><mo>=</mo><mi>π</mi><mo>×</mo><msup><mrow><mo fence="true">(</mo><mfrac><mi>D</mi><mn>2</mn></mfrac><mo fence="true">)</mo></mrow><mn>2</mn></msup></mrow></semantics></math>

    <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>A</mi><mo>=</mo><mi>π</mi><mo>×</mo><msup><mrow><mo fence="true">(</mo><mfrac><mn>0.125</mn><mn>2</mn></mfrac><mo fence="true">)</mo></mrow><mn>2</mn></msup></mrow></semantics></math>

    <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>A</mi><mo>=</mo><mi>π</mi><mo>×</mo><mn>0.0625</mn></mrow></semantics></math>

    <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>A</mi><mo>≈</mo><mn>0.1963</mn><mtext> </mtext><mtext>square feet</mtext></mrow></semantics></math>

    Now, we can calculate the flow rate:

    <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>Q</mi><mo>=</mo><mn>0.1963</mn><mo>×</mo><mn>0.479</mn></mrow></semantics></math>

    <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>Q</mi><mo>≈</mo><mn>0.094</mn><mtext> </mtext><mtext>cubic feet per second (cfs)</mtext></mrow></semantics></math>

    To convert cubic feet per second to gallons per minute, we need to multiply by a conversion factor. Since 1 cubic foot per second is approximately 448.831 gallons per minute, we'll use that conversion factor:

    <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>Q</mi><mo>≈</mo><mn>0.094</mn><mo>×</mo><mn>448.831</mn></mrow></semantics></math>

    <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>Q</mi><mo>≈</mo><mn>42.285</mn><mtext> </mtext><mtext>GPM</mtext></mrow></semantics></math>

    So, approximately 42.285 gallons per minute will flow from the 1.5" copper pipe at 40 PSI with the given conditions.

    Another site had around 85.

    We're actually doing this math now, expanding and adding a brewhouse. The engineers are insisting we add a city water buffer tank, as the new house will probably consume more than we can supply (even with a 2" line at like 90psi lol). A buffer tank and a pump may be the way your buddy needs to go too.



    ------------------------------
    Craig Murphy | Plant Manager
    Jack's Abby Craft Lagers, Framingham MA
    (857) 231-1356
    craigm@jacksabby.com
    ------------------------------



  • 5.  RE: Water Flow Rate Requirement

    Posted 04-11-2024 19:29

    Craig,

    Thanks for the sanity check!  This "simple" question is definitely not so easy, especially when you bring in our buddy Chat.  A buffer tank for tank rinsing is being considered as well as selecting different CIP devices for the cellar tanks with a lower flow requirement.  I did overstate the predicted maximum flow; that is probably a bit closer to 80 gpm.

    Cheers, Ashton



    ------------------------------
    Ashton Lewis
    Manager of Training and Technical Support
    BSG Craftbrewing
    MBAA District Great Plains, Technical Chair
    Springfield, Missouri
    (417) 830-2337
    ------------------------------



  • 6.  RE: Water Flow Rate Requirement

    Posted 04-12-2024 14:32
    Based on my experience at 40 psi, 1.5" incoming main is the bare minimum if you are running a 10 BBL system.  If you keep your flow rates at 40 gpm or below, it would just work and you will have a little line pressure during use.  However, if during the summer, the pressures drop due to heavy local use, you are going to run into some frustrations. 40 psi is pretty low for a municipal water source.  They typically are designed to run 65 to 95 psi static pressure at the meter.

    If you want to talk buffer tanks, reach out to me and we can discuss pros, cons and how to make them as affordable as possible.  I have designed these into systems before and they can be handy.

    Regards,

    Glen Sprouse
    678-778-0212





  • 7.  RE: Water Flow Rate Requirement

    Posted 04-15-2024 17:26

    Craig and Glenn,

    Thank you for both the information.  My buddy was looking for a sanity check on this and the input is helpful.

    Cheers,

    Ashton



    ------------------------------
    Ashton Lewis
    Manager of Training and Technical Support
    BSG Craftbrewing
    MBAA District Great Plains, Technical Chair
    Springfield, Missouri
    (417) 830-2337
    ------------------------------



  • 8.  RE: Water Flow Rate Requirement

    Posted 04-12-2024 14:33
    Hi Craig,
    The ChatGPT example delta P input mixes gauge and absolute units.  40 PSIG = 54.7PSIA , and 0 PSIG = 14.7 PSIA , thus the delta P is 40 PSI. 

    Keep in mind a practical seat of the pants reference for flow rate: a standard garden hose at a moderate length and typical residential water pressure from a main is about 8 GPM.

    Try rerunning it with the correct units.  (I did not take the time to manually calculate it.)

    Harlan Coomes