ENMET SPECTRUM - Manual (Page 12)

ENMET Corporation SPECTRUM Series
8
3.1.1 Key
Entrance to the maintenance menu is guarded with a four digit numerical key. The factory default setting of the key is
1270*. When the valid numerical key is inserted, the user is allowed to enter the maintenance menu
When in the "go SETUP" location, press the SELECT pushbutton; "Key=0000" is displayed. The underscore cursor
is under the left hand digit. To insert the key, press the OPTION pushbutton to change the left hand digit, and choose
the correct digit; then press the SELECT pushbutton, which locks in the chosen left hand digit and moves the
underscore cursor one space to the right. Continue this process until the four digit key is complete. When the valid
key is inserted in this manner, the display is transferred to the "run ZERO" portion of the maintenance menu. When an
invalid key is inserted, "INVALID" is briefly displayed, and the instrument returns to the operational display.
*The process by which a different key is set is given in section 3.1.6.
3.1.2 Zero
A valid key entry sets the instrument at the "run ZERO" location, of the maintenance menu, which enables the setting
of the zero gas concentration point. This is desirable if the zero reference of the gas sensor has drifted over a period of
time, indicated by a persistent gas concentration reading in a clean environment. Note that the calibration sequence
given below also includes setting the zero point. If a full calibration is required, instead of setting just the zero point,
push the
OPTION button once; "run CAL" is displayed. See section 3.1.3.
To set the zero point without performing full calibration, from the "run ZERO" location press the SELECT
pushbutton; "AIR SET?" is displayed. Be certain that the instrument is in clean air, uncontaminated by the target gas.
If uncertain of the environment, use pure compressed air from a pressurized cylinder, and flow it over the sensor at a
low rate.
With the instrument in “AIR SET?”, press the SELECT pushbutton again. "z30:0.0v" is displayed; this is a counter
that counts down in seconds from 30 to 0. The validity of the new zero setting is then examined; if it is with in preset
parameters, the display is transferred to the operational display in the operation menu.
If the new zero setting is not between preset parameters, "C-FAULT" is displayed. Turn the instrument OFF, then ON
again. This re-boots the system with the most recent valid zero setting.