Emerson OXYMITTER 4000 - Manual (Page 85)

Instruction Manual
IB-106-340 Rev. 3.0
December 2003
Rosemount Analytical Inc. A Division of Emerson Process Management Configuration with LOI 4-5
Oxymitter 4000
4-3 RECOMMENDED CONFIGURATION
a. 4-20 mA Signal Upon Critical Alarm
Rosemount recommends that the factory
default be utilized. The 4-20 mA signal will
go to the 3.5 mA level upon any critical
alarm which will cause the O
2
reading to be
unusable. Customer can also select 21.6
mA as the failure setting if normal opera-
tions cause O
2
readings to go below the
zero % O
2
(4 mA) level. If the O
2
measure-
ment is being utilized as part of an auto-
matic control loop, the loop should be
placed into manual upon this failure event
or other appropriate action should be taken.
b. Calibration
Rosemount recommends utilizing an auto-
calibration system, actuated by the “calibra-
tion recommended” diagnostic. New O
2
cells may operate for more than a year, but
older cells may require recalibration every
few weeks as they near the end of their life.
This strategy ensures that the O
2
reading is
always accurate, and eliminates many un-
necessary calibrations based on calendar
days or weeks since previous calibration.
When utilizing the SPS 4000 or the IMPS
4000, consider wiring some or all associ-
ated alarm contacts.
1. CALIBRATION INITIATE. Contact
from the control room to an SPS 4000
or IMPS 4000 (one per probe) provides
the ability to manually initiate a calibra-
tion at any time from the control room.
Note that calibrations can also be initi-
ated from a HART handheld communi-
cator, from Asset Management Solu-
tions software, or from the keypad on
the Oxymitter 4000.
2. IN CALIBRATION. One contact per
probe provides notification to the con-
trol room that the “calibration recom-
mended” diagnostic has initiated an
automatic calibration through the SPS
4000 or IMPS 4000. If the O
2
signal is
being utilized in an automatic control
loop, this contact should be utilized to
place the control loop into manual dur-
ing calibration.
3. CALIBRATION FAILED. One contact
per probe from an SPS 4000 or IMPS
4000 to the control room for notification
that the calibration procedure failed.
Grouped with this alarm is an output
from a pressure switch which indicates
when the calibration gas bottles are
empty.
4. 4-20 mA SIGNAL DURING CALI-
BRATION. The 4-20 mA signal can be
configured to respond normally during
any calibration, or can be configured to
hold the last O
2
value upon the initiation
of calibration. Factory default is for the
4-20 mA signal to operate normally
throughout calibration. Holding the last
O
2
value may be useful if several
probes are being averaged for the pur-
pose of automatic control. Unless sev-
eral probes are being averaged, always
place any control loops using the O
2
signal into manual prior to calibrating.