<1. Introduction and General Description>
1-5
IM 12J05D02-01E
l
Salinity compensation
In order to take the effect of salinity into account for oxygen measurement an average chloride
concentration can be programmed. The chloride concentration value is set manually via
the service level. The EXA DO402 takes account of the effects of salinity and temperature
simultaneously. The advantage of this construction is that the result of the measurement is
available immediately. A separate conversion table is not necessary.
l
Temperature compensation
The micro-processor makes an accurate temperature compensation possible that performs well
over the entire range of the instrument. No further adjustment tables are required.
l
Barometric air pressure compensation
Air pressure differences, due to weather conditions or altitude, can cause a variation up to 20 %
in the dissolved oxygen concentration. A built-in air pressure sensor automatically compensates
for barometric influences between 900 to 1100 mbar (90 to 110 kPa).
l
Sensor diagnostics
The DO sensor is checked for low impedance between the silver electrode and an earth
contact in the liquid, to detect membrane integrity. Temperature sensor connections and sensor
connections are checked for impedance. These faults are signalled by the FAIL contact and can
be signalled to the control room by an output of 0/3.5 mA or 22 mA. The fault is also signalled
by a special marker held on the display, a LED on the front and an error code in the message
display.
During calibration of a DO measuring system the slope deviation from nominal value (%) and
sensor output (μA) at 0 mg/L are calculated and checked.
If any of these are outside the limits, an error is signalled.
l
Logbook
Software record of important events and diagnostic data. Available through RS-485, for use with
the Yokogawa PC402 communication software.
l
Serial Communication
Bi-directional according to the EIA-485 standard using HART-protocol and PC402 software.
9th Edition: Aug. 05, 2015-00
Содержание EXA DO402G
Страница 9: ...Blank Page...
Страница 23: ...Blank Page...
Страница 77: ...Blank Page...
Страница 81: ...Blank Page...
Страница 85: ...Blank Page...
Страница 86: ...9 Spare Parts 9 1 IM 12J05D02 01E 9 Spare Parts See Customer Maintenance Parts List 9th Edition Aug 05 2015 00...
Страница 87: ...Blank Page...
Страница 95: ...Blank Page...