51-638 Echotel Model 338 Two-Wire Ultrasonic Transmitter
22
P46
Reference distance
Factory default value for P46 is: 0.00
Reference is the distance from the face of the transducer to
the point where the flow rate becomes zero. This distance
is different for each type of flume or weir. Measure the ref-
erence distance as shown in the following pages of flumes
and weirs and enter into P46.
Flume/Weir Dimensions
P40 = 00 to P40 = 08
P40 = 00 to P40 = 08 are not used for open channel flow
applications.
P40= 09 Parshall flume
Parshall flume sizes are designated by their throat width.
This width is entered in P42 using the same units as
selected in P00. The reference distance must also be
entered in P46.
The sensor is mounted over the flume at a distance of
2
⁄
3
(A)
behind the throat. The head (h) is also shown at left.
When configuration is completed, the head value can be
viewed in P76.
P40= 10
Palmer-Bowlus flume with (D/2)
Palmer-Bowlus flumes make a transition from a circular
bottom section to a raised trapezoidal throat and then
transition back to the circular bottom section.
The range (P04) value is larger than the reference distance
(P46) as shown at left. Enter values for P40, P41, P42,
and P46.
P40= 11
Palmer-Bowlus flume with (D/3)
Palmer-Bowlus flumes make a transition from a circular
bottom section to a raised trapezoidal throat and then
transition back to the circular bottom section.
The range (P04) value is larger than the reference distance
(P46) as shown at left. Enter values for P40, P41, P42,
and P46.
Sensor
Sensor
P42
P46
h
/ A
A
2
3
P46
P04
D/2
D/10
D
P41
h
1
2
P46
P04
D/3
D/10
D
P41
h
1
2
