S4000C
20
The unit is now calibrated and the new ZERO and SPAN values have been stored in the non-
volatile memory (EEPROM).
4.6.2 Aborting
Calibration
If calibration is to be aborted, and gas has not been applied, wait ninety seconds and reapply
the magnet. The unit will return to normal operation with the previous calibration values
unchanged.
NOTE:
Once gas has been applied, it is not possible to abort a calibration.
If the Model S4000C is placed in the Calibration Mode and no gas is applied for six minutes,
the unit will revert to a Fault condition. Re-applying the magnet over the GM Logo will return the
unit to operational mode with the previous calibration values unchanged.
4.6.3 Adjustable Calibration Level
The Model S4000C provides the user with the ability to adjust the calibration level from 25%
LEL to 90% LEL. The default value from the factory is 50% LEL. This allows the user to utilize
gas already available at their installation, that is not 50% LEL of the gas being detected, or to
perform cross-calibration to a similar gas. Adjusting the Calibration Level is performed in Setup
Mode.
NOTE:
%LEL to %Volume Fraction is converted by using 325 Guide to Fire Hazard properties
of Flammable Liquids, Gases, and Volatile Solids. For example, 100% LEL CH4 is
shown in NFPA to be 5% Volume, Calibration is at 50% LEL or 2.5% Volume.
WARNING:
General Monitors recommends calibrating the Model S4000C with 50% LEL of
the gas being detected. This provides the most accurate calibration, since the
Model S4000C is optimized for this concentration. The accuracy of the calibration
may be reduced by using a different calibration level, and this inaccuracy will
increase as the calibration level varies from 50% LEL.
4.6.4 Remaining Sensor Life
The Model S4000C Intelligent Sensor provides an estimate of remaining sensor life, in percent
remaining, to provide the user with an early warning of the need for sensor replacement. The
remaining sensor life is updated each time the unit is calibrated. The current remaining sensor
life estimate is displayed during the zeroing portion of a calibration sequence. It can also be
read via the MODBUS interface (Section 8.8.17).
NOTE:
The remaining sensor life provides an estimate of the amount of life remaining for the
sensor. Many factors including, environmental conditions, poisons, etc can affect this
estimate. It should be used only as an estimate for preventive maintenance and logistic
purposes.
4.6.5 Initializing the Remaining Sensor Life
The remaining sensor life estimate must be initialized each time a new Hydrocarbon Sensor is
installed. The initialization should be done during the first calibration of a newly installed sensor.
After the sensor has been on power for a minimum of one hour, enter calibration mode as