Chapter 8. Servicing the PT878
172 Transport® Model PT878 Portable Liquid Flowmeter User’s Manual
8.5 Programming the Thickness Gauge (cont.)4. The signal inversion prompt enables you to invert the thickness
transducer signal. Signal inversion may be necessary if your thickness
readings show unusual jitter, or for certain unusual combinations of
pipe and fluid or pipe and lining. Consult the factory before measuring
the thickness of lined pipes.
Note: When measuring the thickness of certain pipe materials, you might
need to drain the pipe before measuring the pipe wall, because
certain pipe/liquid combinations muffle the ultrasonic echo.
Signal inversion should be on, unless you have received other instructions.
To change its status, use the [W] and [X] arrow keys to move to the
appropriate radio button and press [ENTER].
5. To enter the noise threshold:
a. Press [ENTER] to open the text box.
b. Use the numeric keys to enter the desired value.
c. Press [ENTER] to confirm your entry.
6. The final value, the detection threshold, represents the percent of peak
the PT878 uses to make measurements. It will consider anything above
the entered percentage as part of the signal. To change this value:
a. Press [ENTER] to open the text box.
b. Use the numeric keys to enter the desired value.
c. Press [ENTER] to confirm your entry.
You have finished entering values for the Programming window. To leave
this window:
•Press the [W] arrow key to move to the Materials tab.
•Press [F2] (Cancel) to return to Operate Mode without confirming the
changes. The PT878 returns to Operate Mode.
•Press [F3] (OK) to confirm the new data and return to Operate Mode. The
PT878 returns to Operate Mode.