Procedure - Zeroing The Sensor Using Deltav - Emerson ROSEMOUNT 5081-A Instruction Manual

MODEL 5081-A
11.3 PROCEDURE — zEROING THE SENSOR USING Deltav
1. Complete the startup sequence described in the SCS921 instruction manual. Adjust the sample flow to
between 80 and 100 mL/min, and set the sample pressure to between 3 and 5 psig.
2. Remove the reagent uptake tube from the reagent bottle and let it dangle in air. the peristaltic pump will sim-
ply pump air into the sample.
3. Let the system run until the sensor current is stable. the current will drop rapidly at first and then gradually
reach a stable value. to monitor the sensor current, go to the main display. Press dIAG followed by NEXt.
the SEnSor Cur prompt appears. Press ENtER to view the sensor current. Note the units: nA is nanoamps;
µA is microamps. typical zero current for a total chlorine sensor is -10 to +30 nanoamps.
A new sensor or a sensor in which the electrolyte solution has been replaced may require several hours (occa-
sionally as long as overnight) to reach a minimum zero current. do Not StARt tHE ZERo RoutINE uNtIL
tHE SENSoR HAS BEEN IN ZERo SoLutIoN FoR At LEASt tWo HouRS.
4. Access: deltaV Explorer/Context Menu
Zero Amperometric Sensor (method_sensor_zero)
Method Steps:
a. displayed: Current total Chlorine Measurement
Zero limit
Prompt: Is PV less than limit?: Yes; No; Abort
Selecting "Yes" to a total chlorine measurement greater than the zero limit will
cause the measurement to be accepted as the zero value. Selecting "No" will
cause the total chlorine measurement to be re-read. the new total chlorine
measurement may be closer to the zero limit. If the total chlorine measurement
is significantly greater than the zero limit, the method should be aborted
("Abort") and restarted after sufficient time for the total chlorine reading to
approach the zero limit.
b. If "Yes" is chosen, the Current total Chlorine Reading and the new Zero Current Value are displayed.
the method then concludes.
NOTE
SECTION 11.0
CALIBRATION - TOTAL CHLORINE