GE DigitalFlow XMT868i - Page 84

Appendix C. Measuring P and L Dimensions
76 DigitalFlow™ XMT868i Startup Guide
C.1 Measuring P and L (cont.)
Use Figure 23 below 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.
Figure 23: Determining the Pipe Coupling Length
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”
• Transducer face depth (FD) = 1.75”
• Mounting Angle (MA) - 45
o
The P dimension would be [48 + 2(3/8)]/(0.7071) + 2(2.0 - 1.75) = 69.4”
FD
CL
MA = 45°