<PG400 Pulse Generator for Clean Unit>
15
IM 19C01B05-01EN
2nd Edition : Jul. 06, 2021-00
CAUTION
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When the oscillator does not contact fluid, turn off the output switch to avoid damages to
instrument.
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Tighten the four front cover screws to the torque of 1.5 to 1.6 N·m.
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Adjusting ultrasonic power
In ultrasonic cleaning, cavitation caused by the application of ultrasonic waves contributes to the
cleaning effect. The more cavities are produced, the more the cleaning effect is enhanced.
In turbidity measurement using an optical system or pH measurement, however, measured
values are more largely influenced with increase in the number of cavities produced.
PG400 can adjust the ultrasonic power so that the influence on measurements is controlled to
within an allowable range and provide the most efficient cleaning.
Adjusting the ultrasonic power is recommended, when using for the first-time, replacing the
ultrasonic oscillator, or changing the process flow rate.
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Adjusting Procedure
Adjust the ultrasonic power by turning the volume adjuster. Adjust it so that the measurement
difference of turbidity detector or pH sensor can fall within an allowable range between when the
ultrasonic cleeaning is on and off.
(1) Turn OFF the output switch of PG400. Then, feed a sample water into the turbidity detector
or pH sensor at the same flow rate as in a steady-state operation. Actuate the turbidimeter
or pH analyzer.
Note: Even if the ultrasonic power is the same, the influence of ultrasonic waves on measured values varies depending
on the properties (velocity of flow and amount of suspended solids) of fluid in the sample cell.
(2) Keep the output switch turned OFF. Wait until the turbidity or pH measurement becomes
stable then record the measurement value.
(3) Turn ON the output switch of PG400. Wait until the turbidity or pH measurement becomes
stable then record the measurement value.
(4) Compare the result from (2) and (3). If the difference between the two measurement
is within an allowable range, the adjustment is complete. If not, you need to adjust the
ultrasonic power. Insert a flathead screwdriver into the slot of the volume adjuster and turn it
counterclockwise to reduce the ultrasonic power. (Figure.3.1) Then, return to (3).
Note:In case the power seems to have lowered excessively, turn it clockwise to increase the power.
Then, return to (3).
4. Maintenance
The PG400 requires very little periodic maintenance, except to make sure the front window is
kept clean in order to permit a clear view of the LED.
If the window becomes soiled, clean it using a soft damp cloth or soft tissue. To deal with more
stubborn stains, a neutral detergent may be used.
When you must open the front cover and/or remove cable glands, make sure that the seals
are clean and correctly fitted when the unit is re-assembled in order to maintain the housing’s
weatherproof integrity against water and water vapor.
CAUTION
Never use harsh chemicals or solvents. If the window does become heavily stained or scratched,
parts replacement might be required.
Contact Yokogawa service when replacing the front cover. Part numbers are K8008DC (Code of Housing “-B”, Urethane
coating), or K8008DF (Code of Housing “-D”, High anti-corrosion coating).
