PART THREE - OPERATION
SECTION 4 - TRANSMITTER CALIBRATION
Rev. 0-201
PRO-series Model C3 Conductivity Transmitter
53
4.4 1 POINT SAMPLE
Method
(wet calibration)
SPECIAL CASE -- ALTERED SENSOR CABLE LENGTH
(only for sensors with Pt 1000 temperature element*)
Changing the standard 20 ft. (6 m) sensor cable length, by
shortening it or adding an interconnect cable, affects tempera-
ture measuring accuracy. The GLI-certified T FACTOR is based
on standard cable length. To compensate for altered cable
length measuring error, change the certified T FACTOR entry:
•
Shortened Sensor Cable: To increase the transmitter tem-
perature reading to match the known solution temperature,
decrease the T FACTOR by 3.85 ohms for each
°
C difference.
•
Added Interconnect Cable: To decrease the transmitter tem-
perature reading to match the known solution temperature,
increase the T FACTOR by 3.85 ohms for each
°
C difference.
Example:
Suppose the known solution temperature is 50
°
C and
the transmitter reads 53
°
C due to interconnect cable resistance.
Multiply the 3
°
C difference by 3.85 ohms to get 11.55. Then in-
crease the sensor T FACTOR by adding 11.55 to it and entering
that value. If, due to a shortened sensor cable, the transmitter
was reading 3
°
C less than the known solution temperature you
would decrease the sensor T FACTOR by subtracting 11.55
from it.
*Sensors with a Pt 100 temperature element provide inherently less
accurate temperature readings and are not recommended.
6.
After the
screen re-appears, press
MENU key
once and then
ESC key
once to display the
MEASURE screen.
This completes GLI’s DRY-CAL calibration.
This “wet” calibration method requires you immerse the
sensor into a properly prepared conductivity reference solu-
tion of known value, or to keep the sensor installed in the
process while obtaining a process sample. When keeping
the sensor installed, determine the process value by labo-
ratory analysis or comparison reading. In either case, enter
the known reference solution or sample conductivity value.
Recommendation:
For best accuracy when using a new
sensor or after cleaning an existing sensor, perform a
“RESET CALIBRATE” using the TEST/MAINT menu (PART
THREE, Section 5.8) before calibrating.
