YOKOGAWA PH450G

<4. Operation>
4-8
IM 12B07W01-04EN 1st Edition : Nov 11, 2016-00
Table 4.1 Parameters Related to WASH Operation
Parameter
Setting up on Shipment
PH450G FLXA202 or FLXA21
Interval between WASHs 8 hours
(setting range: 0.1 to 36.0 hours)
8 hours
(setting range: 0.1 to 36.0 hours)
WASH time 4 minutes
(setting range: 0.1 to 10 minutes)
4 minutes
(setting range: 0.1 to 10 minutes)
Relaxation time 30 seconds
(setting range: 0.1 to 10 minutes)
30 seconds
(setting range: 0.1 to 10 minutes)
Output signal Hold (the value immediately before) Hold (the value immediately before)
4.3.8 Verifying WASH Operation
First conrm that the PH8HS3 holder is properly installed to ensure that:
(1) The tip of the pH sensor is always submerged in the measured solution in the measurement
mode even if the liquid level varies.
(2) The bottom plate of the cleaning chamber does not become submerged in the measured
solution.
Next turn on the MANUAL WASH switch in the control box and conrm that the chemical
cleaning system operates normally to ensure that:
(3) The sensor holder rises at the same time the switch is turned on and reaches the upper limit
smoothly without delay (before the CYLINDER FAIL signal is output).
Note: When the sensor holder reaches the upper limit, the DETECT UPPER LIMIT signal is
output.
(4) No chemical solution leaks from the gasket on the bottom plate of the cleaning chamber.
(5) The sensor holder descends smoothly without delay at the same time the switch is turned
off.
After completing verication of these operations, have the PH450G or the FLXA202/FLXA21
output the WASH contact signal to make sure that the WASH operation of the chemical cleaning
pH measuring system is carried out properly.
Note: Shorten the preset interval between WASHs to approximately 30 minutes when
performing the WASH operation. Note that the pH converter system for outdoor use can
also be put into the WASH operation by using a remote contact-input signal.
4.3.9 Calibration with Standard Solution
Before starting regular operation, apply calibration with a standard solution. Refer to the
instruction manual supplied with PH450G or FLXA202/FLXA21.
4.4 Regular Operation
After completion of required startup procedures, you can put your system into regular operation.
This section deals with items for routine inspection during regular operation and precautions that
must be observed when shutting down the system.
4.4.1 Data Acquisition in Early Stages of Operation
Implementing WASH too often will lead to a waste of the chemical solution, making your system
uneconomical. It is, therefore, often advantageous for the number of cleanings to be reduced,
provided that this ensures that the measurement error always falls within the specied range,
The settings for the parameters related to the cleaning operation are provided upon shipment,
assuming that the system is used for a process under standard conditions. Consequently, it is
possible for you to perform more efcient cleaning depending on your process condition.