ENMET SPECTRUM - Manual (Page 13)

SPECTRUM Series ENMET Corporation
9
3.1.3 Calibration
N OTE : Calibration must be performed at normal room temperature (20-25°C) for optimal performance. If the
instrument is exposed to temperature extremes just prior to calibration, allow it to stabilize to room temperature.
The internal temperature of the instrument is verified by cycling through the "see DATA" menu.
In order to calibrate the instrument, it is first zeroed in a procedure similar to the one described section 3.1.2. Then the
sensor is presented with a known concentration of the target gas, in air or an inert gas such as nitrogen, called the "span
gas". After an appropriate interval, which is timed, the new span setting is examined for validity.
A valid key entry sets the instrument at the "run ZERO" location of the maintenance menu. Press the OPTION
pushbutton once to access the "run CAL" display, then press the SELECT pushbutton; "AIR SET?" is displayed. Zero
the instrument as described in paragraph 3.1.2. When the zero timer is complete, the display indicates "GAS=XXXX",
where the numbers indicate the correct span gas concentration the instrument is equipped to detect; for a
CO
SPECTRUM the span gas is 100 ppm CO, for Cl2 SPECTRUM the span gas is 5 ppm chlorine, and so forth. The
correct span gas is given in Appendix A Table 2 for various target gases.
At the “GAS=XXXX” display:
1. Assure that the correct span gas is available.
2. Connect the calibration adapter to the cylinder along with the correct calibration cover; see Appendix A Table 2.
3. Open the calibration valve so that the span gas flows gently.
4. Press the SELECT pushbutton; "GAS SET?" is displayed.
5. Connect the span gas to the instrument so the calibration gas flows gently over the sensor.
6. Press the SELECT pushbutton; "XXX:Y.Yv" is displayed until countdown is complete.
7. Remove span gas.
The XXX is a counter that counts down in seconds to zero from the correct starting time to provide the proper time
interval for calibration; this time interval may vary depending on your target gas. The Y.Y v indicates a sensor signal
that is used during the sensor replacement procedure. When the timer reaches zero, the new calibration and zero gas
settings are examined for validity. If the value is within preset parameters, the display is transferred to the gas
operational display in the operations menu.
N OTE : After calibration the audio alarm is disabled up to 2.5 minutes.
If the new setting is not within preset parameters, "C-FAULT" is displayed. Turn the instrument OFF, then ON again.
This re-boots the system with the most recent valid zero and calibration settings. Recalibrate. If after recalibration the
instrument still displays “C-FAULT” the sensor may be expired. Replace sensor in accordance with section 3.2.2.
N OTE : A low battery may cause a “Cell Out” indication. Check or replace the 9v battery.
3.1.4 Changing the Alarm Level
A valid key entry sets the instrument at the "run ZERO" location of the maintenance menu. Press the OPTION
pushbutton twice to access the "set ALM" display, then press the SELECT pushbutton; ALM=0000" is displayed.
This is called the alarm update window, and the value displayed is the present alarm setpoint. The underscore cursor is
under the far left digit. Press the
OPTION pushbutton to change the underscored digit; select the desired digit, and
press the SELECT pushbutton to lock in the desired digit and move the underscore cursor one position to the right.
When the desired new alarm point is set “new=XXXX” is displayed. Press either the OPTION or SELECT
pushbutton to exit the alarm update window. If the new alarm setting is valid, "exit" is displayed. Press the OPTION
pushbutton to return to the operational display, or the SELECT pushbutton to return to “run ZERO”.
For the safety of the user, there are upper and lower limits past which the alarm setting is invalid, and the instrument
does not accept them. If an invalid alarm setting is attempted, after the numerical value is inserted in the
"ALM=0000" window, pressing the
OPTION or SELECT pushbutton results in a momentary display of "INVALID"
after which the display returns to the alarm update window. Exiting the alarm update window at this point results in an
alarm point setting unchanged from the value present when the procedure was begun.
Factory default alarm setpoints and alarm limits are shown in Table 1.