11
MODEL 320HP
SECTION 3.0
OPERATION
SECTION 3.0
OPERATION
3.1 GENERAL
This section contains adjustment, standardization, and set-
up instructions to put the sensor in operation. The sensor is
completely automatic and may require only an occasional
electrode cleaning and reference electrolyte replenishment.
See Maintenance, Section 4.0 for instructions.
3.2 START-UP CALIBRATION PROCEDURE
3.2.1 Buffer Calibration Method
1. Ensure that the following items are available for buffer
calibration:
A. Buffer solutions 4, 7 and 10 pH.
B. Buffer cup fixture (Figure 3-1).
C. Buffer calibration liquid junction.
2. Insure there is no process flow through stainless steel
flow cell if Model 320HP is installed. Remove reference
cell from flow cell and install the buffer calibration liquid
junction in place of the high purity foam junction or ship-
ping plug.
NOTE
If the high purity foam junction is contaminated
with buffer, a pH offset will occur.
3. Install the buffer cup fixture onto the reference cell as
shown in Figure 3-1. Place the glass end of the glass
electrode into the buffer cup and connect the glass elec-
trode connector to the preamp connector (BNC).
4. Insure pH analyzer is wired properly to the Model 320HP
Sensor. Fill the buffer cup fixture half full with 7 pH buffer
then apply power to the pH analyzer and allow 10 min-
utes for stabilization of the analyzer reading.
NOTE
For the following calibration steps refer to the ana-
lyzer manual for adjustments of standardize, span
or efficiency.
5. After the analyzer reading has stabilized, standardize the
analyzer to a 7 pH reading. Allow 5 minutes operation to
verify stability. Re-adjust standardization if necessary.
6. Remove the 7 pH buffer from the cup fixture and rinse
with clean potable water.
7. Fill buffer cup half full with 4 pH buffer and allow 5 min-
utes for stabilization of the pH reading. Adjust the analyz-
er’s span of operation for a 4 pH reading.
8. Remove the 4 pH buffer and rinse thoroughly with potable
water. Fill the buffer cup fixture half full with 10 pH buffer
and allow 5 minutes for stabilization. Verify the pH read-
ing is 10 pH ± 0.1 pH.
NOTE
If the 10 pH reading is outside of the afore-men-
tioned tolerance verify the temperature compen-
sator is stable at a constant ohmic value and recal-
ibrate by repeating Steps 5 through 8.
9. Remove 10 pH buffer from the buffer cup fixture and rinse
with potable water. Remove the buffer cup fixture from
the reference cell. Remove power from the analyzer.
10. Remove glass electrode connector from the preamplifier
connector (BNC). Install the glass electrode into stainless
steel flow cell and reinstall the electrode connector to the
preamplifier’s BNC.
11. Remove the buffer calibration liquid junction from the ref-
erence cell and install the high purity foam junction. Install
the reference cell to the flow cell (see Section 2.3).
12. Complete sensor installation if not already done. Refer to
the sensor installation procedure of this manual.
3.2.2 On Stream Sensor Calibration Method.
1. Place the sensor on stream. Adjust rotometer to the prop-
er flow rate (see Figure 2-2). Allow 2 to 3 hours for full
sensor stabilization.
2. When the reading is stable, note its value and immedi-
ately obtain a sample of the solution, near the sensor.
Insure that the sample is sealed from the atmosphere to
avoid changes to the pH value.
3. Check the above sample on a bench meter. Standardize
the analyzer as necessary to obtain agreement with the
bench meter. Take more than one sample to assure max-
imum accuracy.
FIGURE 3-1.
Buffer Cup Fixture
Buffer
Cup
Fixture
Reference
Cell Assy.