Dynasonics DXN Portable Ultrasonic Measurement System - Manual (Page 50)

In Tubing Mode, the user must lock the reference AFTER the transducer is applied to the pipe. Ultrasonic transit time is
measured as the difference in time between two adjacent-in-time signal reflections. The largest amplitude peak is used as the
reference, Peak 1 and Peak 2 are any detected adjacent peaks to the reference.
Supplementary Information
• Expected error is about 1.5% + 15 mils or 1.5% + 0.4 mm
• Measurement under 0.1” or 2.5 mm is difficult and requires special techniques (tubing mode & thin pipe mode).
• Does not measure liner thickness.
• May not always work on all materials, conditions, and fluids.
• In thin metal and metal pipe modes, the reference can disappear from the display once the transducer is applied to
the pipe. This is why the reference is locked prior to placement on pipe.
[Pipe] Roughness (Numeric Value in Micro Feet)
Surface roughness is the measure if the small surface irregularities in the pipe surface and is composed of three components:
roughness, waviness and form. These are the result of the manufacturing process employed to create the surface.
Surface roughness average (Pipe R), also known as arithmetic average (AA) is rated as the arithmetic average deviation of the
surface valleys and peaks expressed in micro inches (µ inches).
The DXN provides flow profile compensation in its flow measurement calculation. One of the components of that calculation
is roughness. The ratio of average surface imperfection as it relates to the pipe internal diameter is used in this compensation
algorithm and is found by using the following formula:
Pipe R
RMS Measurement of the Pipes Internal Wall Surface
Inside Dia
=
m meter of the Pipe
DXN Portable Ultrasonic Measurement System
Page 50 February 2013