ENMET SPECTRUM ON-LINE - Manual (Page 9)

Spectrum ON-LINE ENMET Corporation
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3.2 Gas Concentration Display and Alarms
The LCD furnishes a numerical display of the target gas concentration from 0000 to the upper limit of the range,
shown in Table 1. The display of the target gas concentration is termed the "operational display". If the target gas
concentration exceeds the upper limit of the range, the display is the numerical upper limit and a plus sign, for
example,"0200+", for hydrogen sulfide. When the concentration of the target gas exceeds the alarm set point, the
audio and visual alarms are activated. The gas concentration continues to be displayed during alarm. The alarm point
is adjustable between a lower and upper alarm limit by accessing the maintenance menu; these and the factory setting
of the alarm point are also given in Table 1. A user should have a justifiable application-based reason for setting the
alarm point higher than the factory setting. When the target gas concentration drops below the alarm point, the audio
and visual alarms cease operation. The alarm point setting can be observed on the display by pushing the OPTION
pushbutton twice.
Some types of gases are difficult to detect in an ambient/static atmosphere. For these types of gases ENMET
recommends using a sampling system similar to ENMET Sample Draw Module 03700-029. See Appendix A Table 2.
For the oxygen S
PECTRUM O N L INE , the zero gas display is 20.9% oxygen, and the two alarm points are at 19.5%
(adjustable) and 23.5% (fixed).
If an alarm concentration is encountered when the display is at a location in the operational menu other than the
operational display, the audio and visual alarms are activated and the alarm cannot be acknowledged.
If the display is left idle at a location other than the operational display for 45 seconds it automatically transfers to the
operational display.
3.4 Alarm Acknowledge
When the instrument is in alarm, and the target gas concentration is below the upper alarm limit, the alarm can be
acknowledged by pressing and releasing the SELECT pushbutton, but only when the instrument is at the operational
display. The acknowledgement causes the temporary cessation of the audio alarm; the red LED continues to be ON.
The audio alarm is OFF for a period of four minutes, after which it is reactivated, if the gas concentration is still above
the alarm point. The alarm can again be acknowledged. However, acknowledgement of the alarm at gas
concentrations above the upper alarm limit does not result in audio alarm cessation, and if the gas concentration rises
above the upper alarm limit during an alarm condition which has been acknowledged, the audio alarm resumes
operation.
3.5 Data
The S PECTRUM O N L INE retains the maximum and minimum gas concentration values encountered since turn-on, or
since the data was cleared and reset. To access this press the OPTION pushbutton three times; "see DATA" is
displayed. Press the SELECT pushbutton; the maximum concentration since turn-on or last reset is displayed. Press
the OPTION pushbutton again; the minimum concentration since turn-on or last reset is displayed. Press the
OPTION pushbutton again; "clr DATA" is displayed. Pushing the SELECT pushbutton clears the data and resets it to
the current concentration. See comments on the use of this feature in Section 4.1.3, Calibration.
Pushing the OPTION pushbutton once more results in a display the internal temperature of the instrument in degrees
centigrade and Fahrenheit. Another push of the OPTION pushbutton results in a display of the version of the code
stored in the instrument. Push the OPTION pushbutton three more times to return to the operational display.
3.6 Interference Gases
For each target gas, some gases other than the target gas cause a sensor response, and thus are termed "interference
gases". A compilation of known interference gases for the various target gases is given in Appendix B, along with
gases that are known to not cause a sensor response.