Emerson 7003M - Manual (Page 47)

Operator Manual
748223-K
June 2002
Rosemount Analytical Inc. A Division of Emerson Process Management Calibration and Adjustments 4-1
SECTION 4
CALIBRATION AND ADJUSTMENTS
4-1 FREQUENCY OF CALIBRATION
When a new sensor is installed, adjust the
zero offset current (Section 3-5d on page 3-
15) and calibrate the instrument with span
gas (4-2b on page 4-1. Span the
instrument weekly at first and note the
stability. Use this information to determine
the regular calibration frequency required
by this particular application.
4-2 CALIBRATION MODE
Refer to Figure 4-1 on page 4-3and Table
4-1 below. From the CALIBRATION Mode,
the operator can:
• Calibrate with span gas
• Enter sample and span gas pressures
KEY DISPLAY WHAT HAPPENS
DISPLAY Nothing Nothing
ACK Nothing Nothing
ALARM 1 Nothing Nothing
ALARM 2 Nothing Nothing
UP ARROW 10.8 →10.9 Changes calibration factor
DOWN ARROW 10.9 →10.8 Changes calibration factor
CAL "PPr" Moves to pressure compensation mode
ENTER "run" Drops back to RUN mode
Table 4-1. CALIBRATION Mode Key Functions
a. Zero Calibration
Each oxygen sensor produces a
constant residual electrical current in
the absence of oxygen due to
characteristics of the sensor. Typically
this current is less that 0.1% apparent
oxygen. It is different for each sensor,
but will remain constant for the life of
that sensor. The instrument can be
zeroed by adjusting the residual current
per Section 3-5d on page 3-15 After
this procedure is performed once, the
zero should not need adjusting again
during the life of the sensor.
b. Span Calibration
1. Expose the sensor to ambient air 1
and let the oxygen reading and
sensor temperature stabilize.
1
We recommend using ambient air in calibration, re-
gardless of the range. Only when monitoring at 0 to
2. Press CAL to enter the
CALIBRATION mode. Enter the
security code if required.
3. CAL flashes and oxygen
concentration is displayed with the
right digit flashing. Output is held
at last reading until returned to
RUN mode.
4. Use the ARROW keys to set the
instrument to the concentration of
the calibration gas. See Table 4-2
on page 4-2 and Table 4-3 on page
4-2 if using ambient air as span
gas.
1% range, can the accuracy of the instrument be
slightly improved by using a gas of lower concentra-
tion (e.g., 1%) for calibration. If bottled air is used,
verify the oxygen concentration against National Bu-
reau of Standards certified calibration gas. The true
oxygen concentration in cylinders is often different
from the concentration indicated on the cylinder label.