Ametek Drexelbrook 505-1320 Series, Инструкция по установке и эксплуатации

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12
505-1320 Series Ultrasonic Open Channel Flowmeter
TM
Increasing time delay to either 15 or 45 seconds will smooth
out a jumpy output signal caused by wave action or turbu-
lence.
The step gain switch can be used to decrease the acoustic
signal and avoid noise interference. See
Figure 4-4 for the
location of the step gain switch.
The standard instrument is capable of shooting to a distance
of 40 feet. Most open channel flow installations shoot a dis-
tance of less than 36 inches. The excess power can cause
measurement inaccuracies due to the 12 degree beam angle.
On small throat width Parshall flumes (1,2, and 3-inch), the
acoustic signal hits the sidewall of the flume. Any slime or
surface irregularities sends a false signal back to the receiver.
By reducing the gain of the transmitter (using the step gain
switch) the measurement inaccuracies can be eliminated.
The factory setting is position 3 .
This setting should be adequate for most applications.
If false high readings occur,
decrease the gain.
If loss of echo occurs, increase the gain.
Step Gain Switch
6 100% gain
5 84 % gain
4 67% gain
3 50% gain
2 32% gain
1 17% gain
8% gain
NOTE
If the step gain is adjusted, the instrument should be
recalibrated using the secondary calibration procedure
described in
Section 4.4 Secondary Calibration.
3.3 Time Delay
3.4 Step Gain Switch
NOTICE