7
12. Press Key “4" once to remove the prompt.
*The LCD will read “000" (Waiting for operator to key in function number to go to).
NOTE: If the operator wishes to check the alarms, leave NO2 calibration gas
flowing into the sensor, otherwise turn off the flow of NO2 calibration gas and inject
Zero Air into the sensor for 1 minute to purge the sensor of NO2 before proceeding.
13. Press Key “3" once to enter function number “001" (Exit CONFIG mode). The LCD
will read “001".
14. Press Key “4" twice to NO2nfirm function 1 (Exit CONFIG mode).
15. The P2621-NO2/VC returns to “Gas Monitoring Mode” with the LCD displaying the
current NO2 NO2ncentration.
VIII) SENSOR REPLACEMENT
The P2057 NO2 sensor should be replaced when the displayed readings on the P2621-
NO2/VC become erratic or the unit can no longer be calibrated. Conspec recommends
replacing all P2057 NO2 sensors in service for 5 years as their continued operation is no
longer assured. Use the supplied hex-key to loosen the tamper-proof screw in the lower
left-hand corner of the P2621-NO2/VC’s door. Use a standard flat blade screwdriver to
loosen the remaining three door retaining screws. Open the door of the P2621-NO2/VC
and unplug the P2057's 4-wire cable from the “J4” Connector on the P2065 Smart
Monitor Card. Clip the wire tie securing the cable to the lower left-hand corner of the
P2065 Smart Monitor Card and discard. Grasp the ring protruding from the bottom of the
P2621-NO2/VC and twist counter clockwise (as viewed from below) while holding the
body of the P2057 inside the enclosure. Unscrew the outer ring (Note: the outer ring
holds the dust screen in place inside the diffusion tube. When the outer ring is removed
care should be taken to retain the dust screen if the P2057 is to be returned for sensor
replacement) and remove the P2057 NO2 sensor from the P2621-NO2/VC enclosure.
Installation of a new P2057 NO2 sensor is accomplished in the reverse order.
NOTE: When a new P2057 NO2 sensor is installed allow 10 minutes for the sensor
to warm up.
IX) TROUBLE SHOOTING
1. No Lights On The Front Panel
Turn OFF the power to the P2621-NO2/VC and to the fan Control system. Open the
enclosure and check that the 24 VAC power supply wiring is securely attached to the
terminals T1 and T2, and that the wiring from the Connector terminals to the circuit
board is securely attached. Turn ON the 24 VAC power to the P2621-NO2/VC. If the
power light is OFF, using a voltmeter, measure the voltage between T1 and T2. The
voltage should read close to 24 VAC. If it does not, the problem is in the power supply
and not in the P2621-NO2/VC. If there is 24 VAC across the T1 and T2 terminals and
