ENMET CD-1300-ST - Manual (Page 9)

CO
2
Sensor / Transmitter ENMET Corporation
7
To verify the CD-1300-ST Series's calibration, proceed as follows:
*N OTE : For instruments with serial numbers of 19180 and below the steps 3 and 4 must be reversed.
1. Remove the front cover of the unit (see procedure Section 3.1).
2. If there is no display on the unit being calibrated, connect a current or voltmeter to the analog output terminals. Check the
setting of the analog output selector (see Figure 2 Section 3.3) to determine whether the unit is set for voltage or current
output.
*3. N OTE whether the shorting block at jumper JP5 is covering both pins or only a single pin, then borrow the shorting
block and slide it over both pins of jumper JP2 (see Figure 2 Section 3.3).
*4. Remove the dust cover from the calibration nipple, attach regulator to cylinder of CO
2
(remove quick release from tubing)
attach the tubing to calibration nipple and allow CO
2
to flow for 1 to 2 minutes or until reading is stable.
5. If the reading differs by more than ± 75 ppm from the known concentration of the calibration gas, use the 'UP' and 'DOWN'
buttons (see Figure 2 Section 3.3) to adjust the reading.
6. When the reading agrees with the concentration of the calibration gas, remove the shorting block on jumper JP2, and replace
in its original position at jumper JP5.
7. Turn off the calibration gas flow, disconnect the gas tubing from the calibration nipple and replace its dust cover. Remove the
meter leads from the terminal strip and replace the front cover (see procedure Section 3.4.1).
5.2 High CO
2
Limit
An adjustable high CO
2
limit is a standard feature of the CD-1300-ST Series. The front panel LED changes from steady to
blinking when the indicated concentration is above the high CO
2
limit value. An optional contact closure is available which
opens or closes when the high limit is exceeded.
5.2.1 Adjusting the High CO
2
Limit
The setpoint value is adjusted by closing jumper JP3 (see Figure 2 Section 3.3). If the display is present when JP3 is closed it
will show the current high limit setpoint in ppm CO
2
.
If there is no display this setting can be adjusted by using a meter connected to the output. In this calibration mode the analog
output is 10,000 ppm at full scale (i.e. 10.0 volts or 20.0 mA). If the voltage output is selected, this scaling corresponds to
1ppm per millivolt or 1 volt per 1000 ppm.
The setpoint is adjusted with the ‘UP’ and ‘DOWN’ buttons while JP3 is closed. When JP3 is opened, the new relay setpoint
takes effect and is stored in non-volatile memory.
The setpoint hysteresis is approximately 40 ppm.
5.2.2 Optional High Limit Contact
The high CO
2
limit option provides a dry (i.e. unpowered) contact closure that activates when the detected concentration rises
above the high CO
2
limit. The high limit is adjustable from 0 to full scale of the unit
5.2.3 Setting High Limit Contact Polarity
The polarity of the high limit contact is set with jumper JP5 as shown in the table below.
Jumper JP5 Relay Operation
OPEN normally closed opens above setpoint
CLOSED (factory default) normally open closes above setpoint
To open jumper JP5 remove the shorting block from the two pins, and replace it so that it engages only a single pin of the
jumper. The shorting block should not be removed; it is required during the calibration procedure.