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In HAMMER, I am getting an error indicating "The tank volume entered is different to the volume computed using the Variable Area Curve."

In HAMMER, I am getting an error indicating "The tank volume entered is different to the volume computed using the Variable Area Curve."  However, I am fairly confident the values I entered are correct.  The Wiki article indicates values in the Variable Area Curve should be relative (percent [0-100] or fraction [0-1]).  However, in the version I am using (10.02.01.06), I am asked for values in meters.  I assume the liquid elevation is actual elevation not the level above the base of the tank.  I also assume that the equivalent diameter is the diameter of a circle with an area equal to the actual volume of the tank divided by the depth of water in the tank. The attached file includes the values entered into the curve.  The error message reads "44947 "New Pump Curve and Demands 2019" "Hydropneumatic Tank" "1126" "HT-1" "The tank volume entered (1059.44001 ft³) is different to the volume computed using the Variable Area Curve (931.696848387049 ft³)." Transient Engine"  1059.44ft3 is equal to 30m3 (the tank volume) but 931.69ft3 equals 26.2 m3 which is not correct.  Any assistance as to what needs to be changed is appreciated.

Lindle Willnow, AECOM

 HAMMER Variable Area Curve.xlsx

  • Hi Lindle,

    Are you modeling a hydropneumatic tank? I tried using a simple "tank" element. But it is showing me depth ratio and volume in percentage only as default?

    This article, How is a variable area tank cross section curve setup? What is the relative depth/volume based on? is for simple tanks modeled with variable area.

    Can you clarify what model units are you using? I am asking this because the program is returning values in cubic feet but you have shared the data in meters. There might be some changes due to the conversion factors involved. If you are working in the SI system try setting the program units to SI. See the below article for reference;

    Changing units in Properties, Flextables, graphs or profiles

    i checked the excel sheet and instead of calculating the total depth (subtracting with 79.2) I calculated the individual depths for each equivalent diameter and was getting a lower volume calculated (about 27 cubic meters). Since the tank is having variable area the individual depths for each step of the equivalent diameters are more accurate since with each equivalent diameter there is change in volume.

    Hope this helps.


    Regards,

    Yashodhan Joshi