Filter
Top Products
MODEL 54eA SECTION 5.0
SOFTWARE CONFIGURATION
5.8 CONFIGURING THE pH MEASUREMENT (continued)
b. Move the cursor to "Diagnostics". Press Edit (F4) and use the
key to change "Off" to "On". Press Save (F4).
NOTE
Choosing "On" means the controller will display pH diagnos-
tic warning messages and fault alarms. Choosing "Off"
means the messages and fault alarms will not be displayed.
Diagnostic variables will still be measured and can be viewed
under the Diagnostics menu.
c. Use the and keys to move through the list of diagnostic
measurements. To change a warning limit, press Edit (F4). Use
the arrow keys to change the setting and press Save (F4) to store
the change. For allowed ranges, see Table 5-1. Setting the limit
to 0 disables the warning limit.
Glass imp hi: High glass impedance implies that the sensor may
be nearing the end of its useful life. Set the warning limit about
two times higher than the impedance of a new electrode. A typi-
cal glass electrode has an impedance of about 150 MΩ at 25°C.
Glass imp lo: Low glass impedance warns of a broken electrode.
A good setting is 20 MΩ.
Zero offset: pH measuring cells are designed to have a potential
of 0 mV in pH 7 buffer. Zero offset is a measure of how far the
true value is from 0.0 mV. Zero offset is calculated every time the
sensor is calibrated. A good limit is 60 mV.
Imped comp: The impedance of a glass electrode is a strong
function of temperature. For accurate comparison of impedances,
readings must be temperature corrected. For best results, leave
"Imped comp" on.
d. Press Exit (F4) to return to the screen in step 6a.
7. To change calibration parameters…
a. Move the cursor to pH calibration and press Enter (F4).
b. Use the and keys to move through the list of items. To make
a change press Edit (F4). Use the arrow keys to the setting to the
desired value and press Save (F4). For allowed ranges see Table
5-1.
Autocal: To disable automatic calibration, choose "Manual". The
other choices in the list ("Standard", "Merck", "Ingold", and "DIN
19267") refer to standard and technical buffers. Refer to the table
in Section 11.0 for a list of the standard buffers. Merck buffers are
pH 2.00, 7.00, 9.00 and 12.00. Ingold buffers are 2.00, 4.01, 7.00,
and 9.21. DIN 19267 are 1.09, 3.06, 4.65, 6.79, 9.23, and 12.75.
Diagnostics : Off
Glass imp hi: 1000 MΩ
Glass imp lo: 20 MΩ
Exit Edit
Autocal : Standard
Stabilize pH: 0.01 pH
Stabilize time: 10 sec
Exit Edit
pH diagnostics
pH calibration
Temperature coeff
Exit Enter
39