GE DigitalFlow DF868 Startup Manual page 72

Appendix D. Measuring P and L Dimensions
D.1 Measuring P and L (cont.)
Use Figure 19 to properly measure the coupling length. Typically, the transducer face is positioned just outside the
inside diameter (ID) of the pipe, or slightly retracted inside the coupling.
Use the following formula to determine the P dimension:
[ID + 2(WT)]/(cos MA) = 2 (CL–FD) = P dimension
For example, given the following:
•
inside diameter (ID) = 48"
•
wall thickness (WT) = 3/8"
•
installed coupling length (CL) = 2.0"
•
a transducer face depth (FD) = 1.75"
•
mounting angle (MA) = 45°
The P dimension would be: [48 + 2(3/8)]/(0.7071) + 2(2.0–1.75) = 69.4"
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Figure 19: Determining the Pipe Coupling Length
DigitalFlow™ Multipurpose Ultrasonic Liquid Flowmeter Startup Guide (1- and 2-Channel)