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| Example 1 | |
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Size an orifice flowmeter using standard ASME-3M to meter
1,000,000 SCFH of air in a 12 in Scd 40 pipe.
o Design (Normal) Flow Rate 80% flow (800,000 SCFH, hw= 64 in water) o Maximum Differential 100 inches of water @ 68 o (1) o Pressure 100 psig o Temperature 100 oF o Pipe Material Carbon Steel o Orifice Material 300 Stainless Steel o Base pressure 14.696 psia o Base Temperature 60 0 F o Energy Cost 0.1 /kwh | |
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The meter type is selected by clicking on Orifice in the Selections display or by clicking on the Selections menu then Device Type from the main menu bar. Differential Producer selections Orifice, Nozzle, Venturi, Fixed Geometry or V-Cone are then presented.
Select Orifice then click the Next button (referred to as Next in this text) to display the Device Type options, in this example, a list of different orifice plates. Selecting Nozzle, Venturi, Fixed Geometry or V-Cone will present meters of these types. The device type options can also be displayed by either clicking on the device type (in this example, Concentric: Flange Taps) or by clicking Selections then Device Types from the main menu bar.
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Click Next to select
Orifice Style, Clamped or Fitting.
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Next presents the available Standards for the selected device type. Only devices that have a standard call up this menu, all other use the information presented in Miller Flow Measurement Engineering Handbook. It is important to note that these standards apply to nominal 2 inch pipe size and larger.
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Next
displays the selection for pressure tap location. This is the
location at which the pressure tap is located for gas (vapor) flows.
Pressure Tap location is also accessed through the main menu bar
under selections.
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Next displays the selection for pipe material. Pipe
material selections are also accessed on the main menu bar under
selections.
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Next shows the primary element material. Primary element material
selections are also accessed on the main menu bar under selections.
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Click Next to display the Special
Factors menu. These factors correct the computation for 1. A mercury meter or manometer (Seldom used but are sometimes in older installations) 2. A drain (for gases) or a vent hole (for a liquid flow) 3. Saturated liquid (not available for this fluid state) 4. Two-Phase flow (for example steam and water)
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If an appropriate factor is selected, you must click Apply to set the selection. As none are selected this case, click Next to show the units for gas flow. The energy cost of 0.1 / kwh is entered here. To change any unit, click on the button displaying the unit. Units can also be modified by selecting Change Units from the unit menu. The Unit Menu be displayed from the main menu under Selections then Units and Base Conditions. Units can be changed from any fluid properties screen, size, flow or DP by double clicking on the unit, as described later.
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Next takes you to the next step the Fluid Properties Selection menu. Fluid properties can also be accessed from the main menu bar under Fluid Properties.
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Fluid properties now are computed by selecting a Standard Fluid or
manually entered by selecting Enter Fluid Properties.
In this example, Next shows the Air computational menu.
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Note the pressure is in psig, click on psia to show the pressure
unit menu and change to psia.
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To change units, for example from psig to psia, click on psia.
Click the Apply button then Next to return to the Air properties
menu. Move the cursor to the Pressure or Temperature inputs to enter pressure or temperature data. Use the enter key, mouse or tab key to navigate the data entry screen. Click DP, Flow, or Size to continue. Back returns to the previous menu.
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Enter the design values, as shown and click on Size. To enter
a known measured pipe diameter, move the cursor to the Enter Pipe
Diameter input box.
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Use Browse to show standard pipe schedules. For this example, select 12 Inch Schedule 40. Click Next to select the pipe. Cancel will return to the previous menu without resetting the pipe size.
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Results are displayed below after clicking on Next in the size menu.
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Click on Print to print the results. Back will
return to the prior menu.
Select Print and the final menu is displayed for changing the Customer, Prepared by, Purchase Order, Tag Number and Document Number. Click on Print to print the results or Back to return to the previous menu. The data sheet is shown below.
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The Flow Vs Dp Screen
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The Accuracy Screen
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