SST GT814, Руководство по конструкции

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814-12 September, 2015
MODEL GT814 NOVA-Sensor ELITE™ Toxic Gas Detector
Failed or Incomplete Calibrations:
The NOVA-Sensor ELITE will wait for up to 5 minutes for gas to be applied during the calibra-
tion procedure. If no gas is detected within the 5 minutes, the calibration will be aborted and
the message CALIBRATION FAILURE, USING PRIOR CALIBRATION DATA is displayed.
The NOVA-Sensor ELITE will then return to normal operation.
!
You may abort or cancel a calibration procedure at any time by momentarily activating
the ▲MagPoint▲ 2 times. The message CALIBRATION CANCELED, ORIGINAL
VALUES WILL BE USED is displayed. You may also abort the calibration by interrupting
the 24 VDC power to the detector.
Possible causes for incomplete calibration are:
1) Gas sensor head failure due to liquid intrusion.
2) Gas detector electrochemical fuel cell electrolyte may have been completely consumed
by exposure to an extremely high concentration of toxic gas over a very long time period.
3) Gas detector electrochemical fuel cell electrolyte may have been completely dried out by
exposure to extremely low relative humidity over a very long time period.
4) Calibration gas applied at wrong time. Gas applied during step 3 above (i.e. too early,
during clean air sampling) will result in negative displays and inaccurate readings. If the gas
is applied too late (which may occur due to the pipe length when remote sensors are used)
it may not reach significant levels before the 5 minute time-out.
Replacing the Electrochemical Fuel Cell Sensor Element
After extended use, the sensing element may age to the point where it will no longer be able
to calibrate properly. This will be indicated by a FAULT after performing a calibration.
!
After the sensor fuel cell element has been in service for 2 years, the detector will display
REPLACE SENSOR CELL as a reminder that the cell is loosing sensitivity. After replacing
the fuel cell with a new one, hold the UP button depressed for about 2 seconds. The dis-
play will read SERVICE ADVISORY CLEARED, and the unit is ready for another 2 years of
operation.
Replacement sensor elements are available from Safety Systems Technology. Ordering
information is in the section headed SPARE Parts. The element is supplied preinstalled on a
small circuit board and is calibrated at the factory to provide a 4-20 mA signal output at the
proper sensitivity for your NOVA-Sensor.
To replace the sensor, loosen the set screw on the front of the sensor head housing and
unscrew the cover from the sensor head. Note the location of the Red and Black wires con -
nected to the terminal block on the existing sensor. Loosen the two screws on the terminal
block and remove the two wires. If the power to the NOVA-Sensor ELITE is still on, be sure
that the ends of the two wires do not touch each other or the metal housing.
Connect the red and black wires to the proper terminals on the new sensor, position the sen -
sor inside of the housing and replace the sensor cover. Tighten the set screw.
Activate the ▲MagPoint▲ on the NOVA-Sensor to start the calibration sequence. This will
recalibrate the detector to the new sensor.