IB-106-340
6-1
SECTION VI. MAINTENANCE AND SERVICE
6-1.
OVERVIEW. This section identifies the calibration
methods available and provides the procedures to
maintain and service the Oxymitter 4000 and optional
integrally mounted SPS 4000.
Install all protective equipment covers
and safety ground leads after equipment
repair or service. Failure to install covers
and ground leads could result in serious
injury or death.
6-2.
CALIBRATION.
a.
During a calibration, two calibration gases with
known O
2
concentrations are applied to the
Oxymitter 4000. Slope and constant values calcu-
lated from the two calibration gases determine if
the Oxymitter 4000 is correctly measuring the net
concentration of O
2
in the industrial process.
Before calibrating the Oxymitter 4000, verify that
the calibration gas parameters are correct by set-
ting the gas concentrations used when calibrating
the unit (See paragraph 4-1a5) 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 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
calibration 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 calibra-
tion or when the response time to the process flue
gases becomes very slow. Each time the diffusion
element is changed, reset the calibration gas flow-
meter to 5 scfh and calibrate the Oxymitter 4000.
To change the diffusion element, refer to para-
graph 6-8.
b.
Three types of calibration methods are available:
automatic, semi-automatic, and manual.
NOTE
A calibration can be aborted any time during
the process by pressing the CAL key (Figure
6-2) on the Oxymitter 4000 keypad three
times in a three second interval or via
HART/AMS or an IMPS 4000. An aborted
calibration will retain the values of the pre-
vious good calibration.
1. Automatic Calibration. Automatic calibra-
tions 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 so the se-
quencer and Oxymitter 4000 can communi-
cate.
Depending on your system setup, an auto-
matic calibration can be initiated by the fol-
lowing methods:
(a)
The Oxymitter 4000’s CALIBRATION
RECOMMENDED alarm signals that a
calibration is required.
(b)
Enter a “time since last cal” parameter
(CAL INTRVL) via HART/AMS that
will initiate an automatic calibration at a
scheduled time interval (in hours). To
configure the CAL INTRVL parameter,
refer to paragraph 7-8.
Содержание Oxymitter 4000
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