Emerson OXYMITTER 4000 - Manual (Page 129)

Instruction Manual
IB-106-340 Rev. 3.0
December 2003
Rosemount Analytical Inc. A Division of Emerson Process Management Maintenance and Service 9-1
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 Oxymitter 4000 and op-
tional integrally mounted SPS 4000.
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 – OXYMITTER 4000 WITH A
MEMBRANE KEYPAD
a. During a calibration, two calibration gases
with known O
2
concentrations are applied to
the Oxymitter 4000. Slope and constant val-
ues calculated from the two calibration gases
determine if the Oxymitter 4000 is correctly
measuring the net concentration of O
2
in the
industrial process. A calibration record sheet
has been provided at the back of this section
to track performance.
Before calibrating, verify that the calibration
gas parameters are correct by setting the
gas concentrations used when calibrating
the unit (see paragraph 5-2a.5 for the key-
pad, or Section 6 for the LOI) and by setting
the calibration gas flowmeter. The calibra-
tion gas flowmeter regulates the calibration
gas flow and must be set to 5 scfh. Only
adjust the flowmeter to 5 scfh after placing a
new diffusion element on the end of the
Oxymitter 4000. 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 Oxymitter 4000 to return to the
normal process reading after the last cali-
bration gas is removed and the calibration
gas line is blocked off. A plugged 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 the re-
sponse time to the process flue gases be-
comes very slow. Each time the diffusion
element is changed, reset the calibration
gas flowmeter to 5 scfh and calibrate the
Oxymitter 4000. To change the diffusion
element, refer to paragraph 9-4j.
b. Three 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 Oxymitter 4000 key-
pad three times within three seconds, or
abort via the LOI, HART/AMS, or IMPS
4000. An aborted calibration retains the
values of the previous good calibration.
1. Automatic Calibration. Automatic cali-
brations require no operator action.
However, the calibration gases must
be permanently piped to the Oxymitter
4000, an SPS 4000 or IMPS 4000
must be installed to sequence the
gases, and the Oxymitter 4000’s logic
I/O must be set to mode 8 via HART/
AMS or the LOI so the sequencer and
Oxymitter 4000 can communicate.
Depending on your system setup, an
automatic calibration can be initiated
by the following methods:
(a) The Oxymitter 4000’s CALIBRA-
TION RECOMMENDED alarm sig-
nals that a calibration is required.
(b) Enter a “time since last cal” pa-
rameter (CAL INTRVL) via HART/
AMS or the LOI that will initiate an
automatic calibration at a sched-