Det-Tronics TXL Series Gas Transmitter - Manual (Page 15)

• If the calibration procedure is not completed or if the
sensitivity of the sensor has deteriorated to the extent
that calibration cannot be successfully completed, a
fault will be generated and the system will automati-
cally revert back to the former calibration settings
(after 2.5 minutes or when the gas level drops below
the lowest setpoint). If a successful calibration cannot
be accomplished, replace the sensor and the
hydrophobic filter (if used) and recalibrate.
• It is recommended to allow the TXL detector to oper-
ate in powered normal mode for a minimum of 24
hours prior to calibration to ensure maximum sensor
stabilization and calibration accuracy.
• Visually inspect the sensor. Loss of sensitivity can be
caused by various factors. One common cause is by
clogging of the hydrophobic or sintered filter by dirt,
oil, paint, etc. Problems of this nature will not be
detected by the transmitter’s diagnostic circuitry. If a
filter is dirty or plugged, it should be replaced.
The TXL gas detector uses an automatic, non-intrusive
calibration procedure, and requires no adjustments by
the operator.
CALIBRATION PROCEDURE
1. If the possibility of background gases exists, purge
the sensor with Det-Tronics compressed clean air to
ensure accurate calibration.
2. The Calibrate mode is entered by holding the calibra-
tion magnet to the magnetic switch target (labeled
“CAL”) on the faceplate of the detector. See Figure
4. Upon activation of the internal magnetic switch,
the digital display will indicate the number “30” and
begin counting down to “0”.
3. When “0” is indicated, the digital display will indicate
"GAS" and then "CAL". At this time, remove the clean
air, if used, and apply the calibration gas to the sen-
sor.
4. The digital display will indicate an increase in the
detected gas level. When 50% of the calibration gas
concentration is displayed (e.g. 25 PPM displayed
with 50 PPM cal gas applied), the display will change
and begin a countdown to zero (0).
5. Upon reaching “0” the detector will revert to normal
operating mode and indicate the concentration of
calibration gas that is applied. Note that upon reach-
ing this condition, the analog signal output level of
the TXL detector will be delayed 60 seconds before
transmitting a live signal to the analog signal receiver.
Be sure to remove the calibration gas from the sensor
as soon as possible (<60 seconds) to preclude any
false alarms.
6. Calibration is complete when the detector returns to
normal mode.
CALIBRATION GAS LEVEL ADJUSTMENT
The preset calibration gas level for the TXL Series of
toxic gas detectors is field adjustable. However, it is
recommended to use a level that equals one half (50%)
of the detector's full scale range of measurement. The
TXL's default settings for calibration gas level typically
provide the recommended setting, and should be used
for most normal gas detection applications. Changes to
the default calibration gas level may change sensitivity,
and therefore the customer assumes all responsibility
for device performance if changes to the default calibra-
tion gas level are made.
Calibration gas level adjustment procedure:
1. Remove the TXL cover by loosening the four corner
screws on the faceplate.
2. Locate the two pushbuttons on the inside of the cover
marked Mode (S2) and Set (S3).
3. Power up the TXL and allow it to enter the Normal
operating mode.
13 95-8541 1.1
PLACE CALIBRATION
MAGNET HERE A2131
Figure 4—Location of Magnetic Calibration Switch