Programming Site Data 4-5
April 2004
Parameters for Special Transducers
3. The prompt asks for the transducer frequency, to transmit a
voltage at a rate to which the transducer can respond.
a. From the Transducer prompt, press the [T] key to reach
the Frequency prompt, and press [ENTER].
b. A drop-down list of five frequencies opens, ranging from
0.25 to 4.00 MHz. Scroll to the frequ ency of your
transducers, and press [ENTER].
4. The next prompt asks for Tw, the time delay. This parameter is
actually the time the transducer signal spends travelling
through the transducer and cable. The P T878GC calculates the
flow rate by subtracting the time of the upstream and
downstream signals, so the time delay must be subtracted out
for an accurate measurement. GE Panametrics supplies the
time delay on a data sheet inside the transducer case.
a. From the Frequency prompt, press the [X] key to reach the
Tw prompt, and press [ENTER].
b. Use the numeric keys to enter the GE Panametrics-
supplied time delay and press [ENTER].
5. When calculating the flow rate, the PT878GC must take into
account the wedge angle, the angle of the ultrasonic
transmission.
a. From the Tw prompt, press the [T] key to reach the
Wedge Angle prompt, and press [ENTER].
b. Use the numeric keys to enter the GE Panametrics-
supplied wedge angle (in degrees) and press [ENTER].
6. The PT878GC must also take into account the wedge
temperature.
a. From the Wedge Angle prompt, press the [T] key to reach
the Wedge Temperature prompt, and press [ENTER].
b. Use the numeric keys to enter the wedge temperature (in
degrees) and press [ENTER].