ENMET SPECTRUM ON-LINE - Manual (Page 12)

ENMET Corporation Spectrum ON-LINE
8
Sensor, Bottom View
4.1.3 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 above. 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.
In some cases, the concentration of target gas in the span gas is greater than the concentration expected in the
workplace. If action is not taken, the calibration gas concentration may become the permanent maximum
concentration retained and displayed as data (see Section 3.5). It is good practice to record any data desired before
calibration, and then to reset after calibration to clear the calibration gas concentration form memory.
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 4.1.2 above. 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 Table 2 of Appendix A, 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.
4. Press the SELECT pushbutton; "GAS SET?" is displayed.
5. Connect the span gas to the instrument so the calibration gas flows over the sensor.
6. Press the SELECT pushbutton; "XXX:Y.Yv" is displayed.
7. Remove span gas
The XXX is a counter which 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
which 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 with in preset parameters, the display is transferred to the gas
operational display in the operations menu.
During calibration the audio alarm is disabled, and after calibration is complete the audio alarm remains disabled for
up to 2.5 minutes.
If the new settings are not within preset parameters, "C-FAULT" is displayed. Unplugging and then plugging in the
power supply turns 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 the sensor in accordance with Section 4.2.1.
*C AUTION : Having the calibration cup too tight will cause the sensor to become deadheaded resulting in an inaccurate
calibration.
Figure 4:Intial Calibration of Replacement Sensor
Opaque, Calibration Cup
*Centered over Sensor
Sensor
Spectrum PCB