1-5
VPT Method
The Velocity Profiling Technique (VPT) was first described by N. T. Debevoise and R. B.
Fernandez in the November 1984 issue of the WPCF Journal. With this method, a series of point
velocity measurements are taken at different depths along the centerline of the flow. These measure-
ments along with level are input into a VPT computer program which calculates the flow. This is one
example of the more advanced profile integration techniques which are possible.
MEASURING LEVEL
Circular Conduits
• Measure the inside diameter of the conduit.
• Measure distance D (Figure 1-4).
• Subtract D from the inside diameter of the
conduit for the depth of flow. This eliminates
the problem of the ruler interfering with the
liquid.
Comment:
The level measurement and the velocity profile
must be on the same plane for proper
application of the continuity equation.
Figure 1-5. Level Measurement
D
Figure 1-6. Location of Level Measurement
NO
LEVEL MEASUREMENT
PLANE OF PROFILE
LEVEL MEASUREMENT
PLANE OF PROFILE
YES
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