Turtle Tough TT-ISE-CL2, Manual

Page: 41 / 51

TURTLE
TOUGH
®
41
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A zero-point calibration is not required for the chlorine sensors included. If there is no chlorine
present in the process medium, approximately zero is indicated. The zero point is independent of
changes in the flow rate, conductivity, temperature and pH value.
If needed, the zero point can be re-set electrically. Simply turn on the analyser with no water running
and touch the calibration button from the home run screen. Touch the Chlorine Zero Edit button, on
the keypad that appears press Clear, enter 0.00, then press Enter, and Return. Press the Home
button to return to the Home screen so that newly entered values will take effect.
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Stable chlorine standards do not exist; because of this the analyser must be calibrated against a
grab sample of the process fluid. Since chlorine residual is so unstable, take the grab sample as
close to the measuring cell as possible and process the sample as quickly as possible.
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Do not interfere with the sample flow to the measuring cell when calibrating; always take the sample
from the flow cell drain or sample tap.
If the value for the nominal slope is under 30%, the membrane cap and the electrolyte must be
replaced and the electrode tip must be cleaned.
1. From the Calibration submenu screen touch the Chlorine Standard Set button. Press the
Clear button, then enter the value determined by your grab sample instrument using the
keypad and press Enter to both clear the previous standard and to enter the new value.
A check mark will appear next to the value.

If the standard value entered exceeds the upper limit of the operating range,
an out of range message will appear in the white box and the value for the calibration
standard will be forced to the operating range upper limit. Go back and re-enter the
desired value.
To enter a new calibration standard value you must first touch the Clear button AND enter a
value AND touch the enter button to erase the previous value.
All values are stored in memory until they are cleared and replaced with another value. Failure to
clear an existing number before entering a new number will produce invalid results. Touching “Clear”
and the “Enter” alone will not clear the value in the register.
2.
Press the Return button to go back to the Calibration submenu screen, and then press the
Home button to return to the main Run screen so that newly entered values will take effect.