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

MODEL 5081-A
10.3 PROCEDURE — zEROING THE SENSOR USING Deltav
1. Place the sensor in the zero standard (see Section 10.1). Be sure no air bubbles are trapped against the mem-
brane. the sensor current will drop rapidly at first and then gradually reach a stable zero 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 free chlorine sensor is -10 to +10 nanoamps.
A new sensor or a sensor in which the electrolyte solution has been replace 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.
2. Access: deltaV Explorer/Context Menu
Zero Amperometric Sensor (method_sensor_zero)
Method Steps:
a. displayed: Current Free Chlorine Measurement
Zero limit
Prompt: Is PV less than limit?: Yes; No; Abort
Selecting "Yes" to a free chlorine measurement greater than the zero limit will
cause the measurement to be accepted as the zero value. Selecting "No" will
cause the free chlorine measurement to be re-read. the new free chlorine
measurement may be closer to the zero limit. If the free chlorine measurement
is significantly greater than the zero limit, the method should be aborted
("Abort") and restarted after sufficient time for the free chlorine reading to
approach the zero limit.
b. If "Yes" is chosen, the Current Free Chlorine Reading and the new Zero Current Value are displayed.
the method then concludes.
NOTE
SECTION 10.0
CALIBRATION - FREE CHLORINE
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