Operator Manual

748223-K June 2002

SECTION 4

CALIBRATION AND ADJUSTMENTS

4-1 FREQUENCY OF CALIBRATION

4-2 CALIBRATION MODE

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.

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 air1 and let the oxygen reading and sensor temperature stabilize.

1We 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 concentration (e.g., 1%) for calibration. If bottled air is used, verify the oxygen concentration against National Bureau of Standards certified calibration gas. The true oxygen concentration in cylinders is often different from the concentration indicated on the cylinder label.

Rosemount Analytical Inc. A Division of Emerson Process Management

Calibration and Adjustments 4-1