Chapter 8. Servicing the PT878
Transport® Model PT878 Portable Liquid Flowmeter User’s Manual 179
8.8.1 Setting up Signal Parameters1. Press the [T] arrow key to enter the window.
2. The first prompt asks for the Delta-T offset. Delta-T is the difference
between the upstream and downstream transit time of the transducers.
The Delta-T offset should normally be set to zero.
Note: Consult the factory before performing this step.
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.
3. The next prompt, the transmitter sample size, is the number of pulses
each transmitter (upstream and downstream) emits. It is set to 8 by
default.
Note: Consult the factory before performing this step.
a. Press [ENTER] to open the drop-down list.
b. Use the [T] or [S] arrow keys to scroll to the desired number.
c. Press [ENTER] to confirm your selection.
4. The next prompt asks for the zero cutoff. Near “zero” flow, the PT878
may have fluctuating readings due to small offsets (caused by factors
such as thermal drift in the fluid). The zero cutoff causes velocity
measurements less than the cutoff to be reported as zero. To set the
cutoff:
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.