KELE CD-AD (01) PDF Document

The KELE CD-AD is a non-dispersive infrared (NDIR) analyzer designed for measuring environmental CO2 concentration in ventilation systems and indoor living spaces. Its measurement range is 0 – 5000 ppm (parts per million), which covers the range required to monitor compliance with ASHRAE or other ventilation efficiency standards. The device provides several output alternatives, including a standard voltage or 4-20 mA current output, an optional LCD readout, and an optional relay contact.

The basic KELE CD-AD model has a single green LED on the front panel that illuminates whenever the unit is operating. The LED’s behavior indicates the CO2 level relative to the high CO2 limit:

LED is on steadily: The measured CO2 concentration is below the high CO2 limit.

LED is blinking: The measured CO2 concentration is above the high CO2 limit.

The standard factory high limit is 1000 ppm, but this can be adjusted in the field.

If your KELE CD-AD has the display option, it includes a 4-digit liquid crystal display (LCD) on the front panel. This display shows the measured CO2 concentration in parts per million (ppm).

To install the KELE CD-AD, first remove the cover and then mount the base.

Cover Removal:

To open the KELE CD-AD, use a coin in the slot on the bottom of the unit to release the snap. Lift the cover up slightly to disengage the closure, then remove the cover with a downward motion to clear the catch at the top of the unit.

Mounting:

The KELE CD-AD is designed for flush mounting with two fasteners. The mounting points are positioned to allow for direct mounting on a standard simplex (single circuit) junction box. A wiring cutout is provided in the center of the unit near the terminal strips.

Wiring for the KELE CD-AD enters the chassis through the cutout in the center of the unit.

Power Supply:

The KELE CD-AD operates from an AC or DC input voltage as specified on page 2 of the operator’s manual. Connect the power supply leads to the two-terminal power connector.

Important: The KELE CD-AD must never be connected directly to line power. Using higher voltages than specified will damage the unit and void the warranty.

If using DC power, you must observe the correct polarity as shown on the circuit board. A reversed polarity connection will not damage the unit, but it will be inoperable until the connection is corrected.

Signal Output:

The KELE CD-AD provides either a 0-10 volt or a 4-20 mA current loop output at the two terminals of the analog output connector. The type of output is determined by the setting of the analog output selector jumper. The analog output is completely isolated from the power supply.

The type of analog output on the KELE CD-AD is determined by the setting of the analog output selector shorting block.

For Voltage Output (0-10V):

Connect the shorting block to the outboard and middle pins of the analog output selector. The output voltage will increase linearly from 0 volts at the low output threshold to 10 volts at the high output threshold. The factory default range is 0 ppm to 2000 ppm.

For Current Output (4-20mA):

Connect the shorting block to the inboard and middle pins of the analog output selector. The output current will increase linearly from 4 mA at the low output threshold to 20 mA at the high output threshold. The factory default range is 0 ppm to 2000 ppm. Ensure the total resistance between the terminals does not exceed the specified maximum loop resistance, otherwise the output current may be erroneously low at high concentrations.

After connecting the KELE CD-AD to a controller or indicator, perform the following check to ensure the connection is correct:

1. Be sure that the output select jumper is set correctly for voltage or current output. If this is not done first, the following check may produce incorrect results.

2. Note whether the shorting block at jumper JP5 is covering both pins or only a single pin. Borrow the shorting block and slide it over the two pins of jumper JP4. The display (if present) will show ‘SEL’.

3. Momentarily closing JP5 will set the unit to full scale output (10V or 20mA). Do not press the buttons on the unit as this will affect the output calibration. If the receiving device does not indicate a full scale reading after JP5 is closed, verify that the wiring is correct.

4. Remove the shorting block from JP4 and restore it to its original position at jumper JP5. The KELE CD-AD will reset and its output will now correspond to the actual detected CO2 concentration.

To replace the cover on your KELE CD-AD, engage the top center of the cover under the latch at the top of the base. Then, press the bottom of the cover onto the base until it latches securely.

The KELE CD-AD is factory set for an analog output range of 0 to 2000 ppm. This can be changed to any sub-range between 0 and 5000 ppm by adjusting the low and high output thresholds. Users of the default 2000 ppm range do not need to perform this adjustment. Follow this procedure to change the range:

1. Note 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 the two pins of jumper JP4. The display (if present) will show ‘SEL’.

2. The display (if present) will show ‘SEL’. Momentarily closing a jumper selects which value to change. If the wrong jumper is selected, simply open JP4 to restart the unit and begin again.

3. Select the low output threshold by momentarily closing JP1. If a display is present, it will show the current low display threshold. If there is no display, the value can be measured with a meter connected to the analog output. In this mode, the output is scaled to 10,000 ppm at full scale (10.0V or 20.0mA), which corresponds to 1 ppm per millivolt.

4. Use the ‘UP’ and ‘DOWN’ buttons to adjust the low output threshold to the desired value.

5. Remove the shorting block from JP4 to save the value; the unit will reset itself.

6. Reconnect JP4. The display (if present) will show ‘SEL’. Select the high output threshold by momentarily closing JP2.

7. Use the ‘UP’ and ‘DOWN’ buttons to adjust the high output threshold to the desired value.

8. Remove the shorting block from JP4 and restore it to its original position at jumper JP5. The KELE CD-AD will reset, and its output will now only change when the gas concentration is within the newly selected range.

The KELE CD-AD is factory-calibrated for sea level. If operated at higher elevations, the calibration must be adjusted. Use the following procedure and table:

ALTITUDE CORRECTION TABLE

Altitude Correction Procedure:

1. Let the KELE CD-AD stabilize to the ambient CO2 concentration, and record the reading in ppm.

2. Multiply the reading by the scale factor from the table corresponding to your operating altitude. For example, if the unit is at 4000 ft (factor 1.14) and reads 420 ppm, the corrected value is 420 * 1.14 = 478.8, which should be adjusted to 480 ppm.

3. Remove the KELE CD-AD’s cover.

4. Note whether the shorting block at jumper JP5 is covering both pins or only a single pin. Borrow the shorting block and slide it over the two pins of jumper JP2. Use the ‘UP’ and ‘DOWN’ buttons to change the concentration to the value you just calculated.

5. Remove the shorting block from jumper JP2 and return it to its previous position on jumper JP5.

6. Replace the cover.

Verification Procedure:

A quick check can be done by supplying the unit with outside air; the reading should stabilize between 375 and 450 ppm. For a more accurate check, use calibration gas of a known concentration (2000 ppm is recommended).

1. Remove the front cover of the KELE CD-AD.

2. If your unit has no display, connect a current or volt meter to the analog output terminals.

3. Remove the dust cover from the calibration nipple, attach a flexible tube, and establish a flow of 50 to 100 cc/min (0.002 to 0.004 SCFM) of calibration gas through the sensor. Allow approximately two minutes for the reading to stabilize.

4. If the reading differs by less than ± 50 ppm from the known concentration of the calibration gas, no adjustment is needed. Proceed to step 7.

Adjustment Procedure:

5. If adjustment is needed, note whether the shorting block at jumper JP5 is covering both pins or only a single pin. Borrow the shorting block and slide it over both pins of jumper JP2.

6. Use the ‘UP’ and ‘DOWN’ buttons to adjust the reading to match the concentration of the calibration gas.

7. When the reading agrees, remove the shorting block from jumper JP2 and replace it in its original position at jumper JP5.

8. Turn off the calibration gas flow, disconnect the tubing from the calibration nipple, and replace its dust cover. Remove any meter leads and replace the front cover.

The high CO2 limit, which determines when the front panel LED blinks, can be adjusted. To adjust the setpoint value, close jumper JP3. If your unit has a display, it will show the current high limit setpoint in ppm CO2.

If there is no display, the setting can be adjusted using a meter connected to the output. In this calibration mode, the analog output is 10,000 ppm at full scale (10.0 volts or 20.0 mA). If 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.

For KELE CD-AD units with the optional high limit contact, the polarity of the contact is set with jumper JP5 as shown in the table below. The high limit itself is adjustable from 0 to the full scale of the unit.

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. Do not completely remove the shorting block, as it is required during the calibration procedure.

The duct kit for the KELE CD-AD contains:

1 dust filter

1 duct probe assembly

2 sheet metal screws

2 lengths of 1/8″ ID tubing

Follow these steps for installation:

1. Select a point along the duct where the probe assembly can be installed into unrestricted airflow, without interfering with internal components like dampers or radiators.

2. Mark and drill the four holes for the duct probe as specified in the installation dimensions. The centerline of the holes must be parallel to the air flow through the duct.

3. Install the duct probe assembly through the holes you just drilled. The sample port must be on the upstream side. Secure the probe assembly in place with the two sheet metal screws.

4. Connect the open ends of the two tubes from the probe assembly to the two sample ports on the base of the KELE CD-AD. It makes no difference which tube is connected to which port on the unit.