Emerson Process Management OXYMITTER 4000 - Manual (Page 119)

Instruction Manual
IB-106-340C Rev. 4.1
July 2004
Rosemount Analytical Inc. A Division of Emerson Process Management Maintenance and Service 9-1
Hazardous Area Oxymitter 4000
SECTION 9
MAINTENANCE AND SERVICE
9-1 OVERVIEW
This section identifies the calibration methods
available and provides the procedures to main-
tain and service the Hazardous Area Oxymitter
4000.
When working on this equipment on
the laboratory bench, be aware that
the Hazardous Area Oxymitter 4000,
probe tube, and flame arrestor hub
can be hot [up to 300°C (572°F)] in the
region of the probe heater.
Install all protective equipment covers
and safety ground leads after equip-
ment repair or service. Failure to in-
stall covers and ground leads could
result in serious injury or death.
9-2 CALIBRATION – HAZARDOUS AREA
OXYMITTER 4000 WITH KEYPAD
a. During a calibration, two calibration gases
with known O
2
concentrations are applied
to the Hazardous Area Oxymitter 4000.
Slope and constant values calculated from
the two calibration gases determine if the
Hazardous Area Oxymitter 4000 is correctly
measuring the net concentration of O
2
in
the industrial process. A calibration record
sheet is provided on the previous page. Use
photocopies of the calibration record sheet
to track transmitter performance.
Before calibrating the Hazardous Area
Oxymitter 4000, verify that the calibration
gas parameters are correct by setting the
gas concentrations (See paragraph 5-2a.5
or 6-5.) used when calibrating the unit and
by setting the calibration gas flowmeter.
The calibration gas flowmeter regulates the
calibration gas flow and must be set to 5
scfh. However, only adjust the flowmeter to
5 scfh after placing a new diffuser on the
end of the probe. Adjusting the flowmeter at
any other time can pressurize the cell and
bias the calibration.
In applications with a heavy dust loading,
the O
2
probe diffusion element may become
plugged over time, causing a slower speed
of response. The best way to detect a
plugged diffusion element is to note the time
it takes the Hazardous Area Oxymitter 4000
to return to the normal process reading after
the last calibration gas is removed and the
calibration gas line is blocked off. A plugged
diffusion element also can be indicated by a
slightly lower reading on the flowmeter.
Change the diffusion element when the
calibration gas flowmeter reads slightly
lower during calibration or when response
to the process flue gases becomes very
slow. Each time the diffusion element is
changed, reset the calibration gas flowme-
ter to 5 scfh and calibrate the Hazardous
Area Oxymitter 4000. To change the diffu-
sion element, refer to paragraph 9-4i.
b. Three types of calibration methods are
available: automatic, semi-automatic, and
manual.
NOTE
A calibration can be aborted any time
during the process. Press the CAL key
(Figure 9-1) on the Hazardous Area
Oxymitter 4000 keypad three times
within three seconds, or abort via the
LOI, HART/AMS, or an IMPS 4000. An
aborted calibration will retain the values
of the previous good calibration.
9