2.0

Calculating Pipe Flow and Other Hydraulic Values by Using the Hazen-Williams Equations
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8 In the Headwater box, type the headwater depth above the orifice opening. The
headwater is measured from the center of the opening. For more information,
see the preceding illustration on orifice values in the introduction of this topic.
9 In the Tailwater box, type the tailwater depth above the orifice opening.
Tailwater is also measured from the center of the opening. For more
information, see the preceding illustration on orifice values in the introduction
of this topic.
The Velocity label displays the computed flow velocity through the orifice. The
box on the right side of the dialog box displays a graphic of the currently
defined orifice. This information is for display only and cannot be edited.
NOTE
If the data you entered has an error, then the orifice graphic image does
not display. Check for an error message at the bottom of the dialog box.
10 Click OK to exit the dialog box.
Specifying an Orifice Coefficient
The Orifice Coefficient dialog box describes orifice shapes and associated
frictional loss coefficients.
To select a coefficient from the dialog box
1 In the Orifice Calculator dialog box, click the Select button next to the
Coefficient box to display the Orifice Coefficients dialog box.
2 Select a coefficient by placing your cursor in the appropriate column and
clicking by anywhere in the text box that contains the value you want to use.
3 Use the navigation buttons on the right side of the dialog box to move through
the list of descriptions and coefficients.
You can add a new orifice coefficient:
n
Click Insert to add a new row above the row you currently have selected.
n
To add data, select an empty text box, and type the new description and
coefficient.
4 Click OK to return to the Orifice Calculator dialog box.
Specifying a Diameter
You can specify a diameter from the Orifice Calculator dialog box by selecting a
beginning and ending point from your drawing.
To specify an orifice diameter
1 In the Orifice Calculator dialog box, click the Select button next to the
Diameter box. The Orifice Calculator dialog box closes temporarily and a
prompt similar to the following is displayed:
Diameter <12.0000 m>:
2 Select the first point of the diameter from the drawing.
The following prompt is displayed:
Second point: