Emerson Process Management OXYMITTER 4000 - Manual (Page 73)

Instruction Manual
IB-106-340C Rev. 4.1
July 2004
Rosemount Analytical Inc. A Division of Emerson Process Management Configuration with LOI 4-5
Hazardous Area 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
(3.5 mA) level.
If the O
2
measurement is being utilized as
part of an automatic 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
unnecessary calibrations based on calendar
days or weeks since previous calibration.
When utilizing the SPS 4000 or IMPS 4000,
consider wiring some or all associated
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
initiated from a HART handheld com-
municator, from Asset Management
Solutions 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
during 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
CALIBRATION. The 4-20 mA signal
can be configured to respond normally
during any calibration, or it can be con-
figured to hold the last O
2
value upon
the initiation of calibration. The factory
default is for the 4-20 mA signal to
track (operate normally) throughout
calibration. Holding the last O
2
value
may be useful if several probes are
being averaged for the purpose of
automatic control. Unless several
probes are being averaged, always
place control loops that are using the
O
2
signal into the manual mode prior to
starting the calibration.
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