Kele KCO-NO2 Gas Sensor User Manual

**Kele KCO-NO2 Gas Sensor User Manual

**

Specifications

Mechanical

Chassis Construction| Robust 18 Ga. Grey powder-coated steel. Hinged & Pad-lockable, or screw-on cover style available.
Weight| 2.0 Lbs
Operating Temperature| -20 to 50°C (-4 to 122°F)
Operating Humidity| 15 – 90 %RH
Storage Temperature| 0 to 20°C (32 to 68°F) to minimize sensor degradation
Case Dimensions (H x W x D)| 6.4” x 5.9” x 2.4” (163.5 x 150.8 x 60.7 mm)
Sensor Vents| Natural Ventilation through 18 0.1” diameter (2.54 mm) vents
Recommended calibration cap diameter| 20.5 mm (.807”)
External Indicators| Separate tri-color LEDs indicates operational status of each senor.
Knockouts| 4 trade ½” knockouts (1 per side)
Electrical

Operating Power Voltage| 13 to 30 VAC (RMS) or 15 to 45 VDC

polarity independent, isolated power supply

Power Consumption| < 5W
Control Relays| Two separate SPDT relays for warning and alarm outputs. 10 Amps max at 120 VAC (RMS) or 30 VDC.

Concentration Reporting Outputs

| Two powered 4–20 mA current loop outputs (one for each sensor). 4 mA output => 0 ppm, 20 mA => full scale output.

Maximum loop resistance: 510Ω

Termination| Removable plugs for use with 12 gauge AWG or thinner
Carbon Monoxide Sensor (CO)

Sensor Type| Electrochemical
Measurement Range| 0 – 100 ppm
Analog Output Range| 4mA to 20mA (corresponds to 0 to 100 ppm)
Accuracy| ±5% of Full Scale (typical)
Calibration Interval| 6 Months; factory calibrated when new
Sensor Life| 2 Year typical
Calibrated Field-Replaceable Sensor| KMOD-CO
Nitrogen Dioxide (NO 2 )

Sensor Type| Electrochemical
Measurement Range| 0 –10 ppm
Maximum Permissible Exposure| 150 ppm
Analog Output Range| 4mA to 20mA (corresponds to 0 to 10ppm)
Accuracy| ± 1.5 ppm (typical)
Calibration Interval| 6 Months; factory calibrated when new
Sensor Life| 2 Year typical
Calibrated Field-Replaceable Sensor| KMOD-NO2
Warranty| 1 year sensor, 7 year electronics

Mechanical Installation

The Model KCO-NO2 is available in two versions of a gray, powder-coated, 18 Gauge steel enclosure. The removable, lockable, hinged-cover version is shown in Figure 1 and the screw-down cover version is shown in Figure 2. All electronics are attached to the front cover. There are ½” conduit knock-outs on all sides for electrical connections. In potentially damp locations the knockout on the bottom of the case should be used to minimize the possibility of water entry. DO NOT USE THE VENT HOLES FOR WIRE ENTRY.

1. This unit is designed to mount to a rigid, vibration-free surface near the middle of the area to be monitored about 5 feet above the floor.
2. It should be located where there is free airflow – avoid corners or recesses.
3. The air vents on the sides of the enclosure should not be closer than 1 foot from the nearest perpendicular wall and must not be obstructed or painted-over.
4. May be mounted in any orientation but hinge on the left side is most common.
5. Mounting holes are made for direct wall screws for the surface encountered. (Mounting screws not provided) or switch box spacing.

Enclosure Dimensions

Figure 1: CO/NO2 Hinged front panel Enclosure Dimensions

Figure 2: CO/NO2 Screw Front Panel Enclosure

mm)

| 1.50” (38.10

mm)

Screw-down| 9/32” (7.14 mm)| 1.50” (38.10

mm)

| 1.50” (38.10

mm)

TABLE 1: Mounting Hole Diameters & Locations 

Electrical Installation

The sensor is not equipped with a power switch; it is operational whenever sufficient power is applied to the power input terminals. All electrical connections to the sensors are made through screw terminals that can be unplugged during wiring. The sensor’s enclosure contains multiple conduit knockouts for flexibility during installation; refer to Figure 1 and Figure 2 for details and dimensions of the enclosures.

Analog Output Connections

Each sensor’s readings are individually reported at the sensor’s two powered 4-20mA analog output connections. Current flows out of the ‘+’ terminal and returns to the ‘- ‘terminal. The CO output is provided at the terminals highlighted green in Figure 3 and the NO2 output is provided at the terminals highlighted yellow in Figure 3. The analog output connection has polarity as labeled on the sensor silkscreen: care must be taken to ensure proper connection. To wire the analog output connections:

1. Power down the sensor, this can be done by unplugging the sensor power terminal (Error! Reference source not found.).
2. Unplug the desired analog output screw terminal (either the NO2 or CO terminal).
3. Connect the signal wires paying close attention to the polarity.
4. Plug the analog output screw terminal back into the sensor.
5. Repeat this process for both analog outputs, then reconnect power

Relay Connections

The detector has two SPDT dry-contact relay output terminals (shown in Figure 4). The relay connections have three-terminal screw connectors that allow devices to be wired to the detector in either normally-open (NO) or normally- closed (NC) configuration. These outputs are activated when ambient air concentrations rise above the sensor threshold settings (refer to Section 4.3 for more information).

In the NO Configuration, the voltage attached to the NO terminal will be present at the COM terminal only when the relay output is activated.

In the NC Configuration, the voltage attached to the NC terminal will be present at the COM terminal while the relay output is deactivated: the voltage attached to the NC terminal is removed when the relay output is activated.

An example wiring diagram for relay connections is provided in Figure 5. When wired as shown, the fan will be energized in both warning and alarm conditions and the alarm will be energized only in the alarm condition.

Figure 4: Relay Outputs

To wire the Warning and Alarm relay outputs:

1. Determine if the device being attached to the relay output should be wired in NO or NC configuration.
2. Unplug the relay output screw terminal.
3. Connect the power source voltage for the device being attached to the detector’s relay output to either the NO or NC location of the screw terminal (Figure 4).
4. Wire the power input of the device being attached to the detector’s relay output to the COM location of screw terminal.
5. Plug the relay output screw terminal back into the correct location on board.

Power Connection

Power connection to the sensor is made at the two-terminal screw connector located at the bottom-right side of the board (highlighted in Error! Reference source not found.). Power to the sensor can be either AC or DC voltage; DC voltage can be connected in either polarity. The input power is electrically isolated from the analog outputs.

To wire power:

1. Open the sensor’s enclosure and unplug the screw terminal labeled POWER on the sensor board.
2. Attach power wires to the screw terminal ensuring the connection is snug.
3. Plug the screw terminal back into the POWER receptacle on the board: this will cause the sensor to power up and begin operation.

It is recommended that all wired connections are connected prior to providing power to the sensor; see the following sections for details on making these connections.

Operational Description

The KCO-NO2 is a ventilation and alarm detector that senses the presence of gasoline or diesel engine exhaust fumes and operates a Warning contact closure to trigger exhaust fans when elevated levels of carbon monoxide (generated by gasoline engines and abbreviated CO) or nitrogen dioxide (from diesel engine exhaust and abbreviated NO2) are detected. If the concentration of either gas exceeds its programmed alarm value, a second set of alarm contacts is operated to trigger an alarm.

The detector has two independent sensor modules; one for sensing carbon monoxide (CO), the other senses nitrogen dioxide (NO2). The sensor modules are field replaceable: each sensor module can be replaced with minimal effort when it reaches end-of-life (EOL) while leaving the main control mounted and wired (refer to Section 7.1).
The device has four factory-preset, pairs of warning and alarm levels for each gas (see Table 4 & Table 6). Each setting determines both the sensor’s warning and alarm thresholds (see Section 4.2). When the concentration of either CO or NO2 rises above its configured warning threshold, the WARNING relay output is activated. When either CO or NO2 concentration rises above its alarm threshold, the sensor’s ALARM relay is activated (refer to Section 4.2). When both the CO and NO2 concentrations are below the warning threshold, the WARNING relay is deactivated; the same action occurs for the ALARM relay.
The front panel has two LEDs indicators, one for the CO and the other for the NO2 sensor module; these LEDs illuminate different colors to indicate normal (green), warning (yellow), alarm (red) and error (blinking red) conditions (see Table 2). The concentrations of CO and NO2 in the ambient air are reported at each senor’s analog output: the analog outputs range from 4 to 20mA during normal operation (see Table 7).

TABLE 3: Conditions when analog output is forced

Table 2: Front panel status LED Indications.

At startup, the sensor has a 15 second warm-up period before it begins normal behavior; during this time the device will.

• Illuminate both the CO and NO2 status LEDs green
• Output the minimum value of 4mA for bothCO and NO2. Analog outputs.
• Deactivate both the Alarm and Warning relay outputs.

Figure 8 : Dip Switch Locations. CO specific adjustments and connections are highlighted in yellow while NO2 specific adjustments and connections are in green.

Setting Warning and Alarm Thresholds

The sensor has a warning and alarm threshold for each gas. These threshold values can be adjusted for each sensor via dip switches on the device’s main board (shown in Figure 8). Refer to details on setting the thresholds for each sensor in Table 4 and Table 6.

TABLE 5: Federal OHSA exposure limits (29 CFR 1910.1051 TABLE Z-1)

TABLE 4 : CO Warn and Alarm Threshold Setting

TABLE 6: NO2 Warn & Alarm Threshold Setting

Warning and Alarm Conditions

The sensor has two LEDs on the front panel (one for each gas. These LEDs change color to indicate the sensor’s current operational status. Table 2 shows the behavior of the front panel LEDs during normal operation. Two dry- contact SPDT relays are provided on the sensor, these relays activate during warning and alarm conditions. Refer to Section 3.3 for location and wiring information.

Sensor Readings
Readings for the two sensors are independently reported on the sensor’s two 4 – 20mA powered current loop outputs during normal operation. Theses outputs are isolated from the operating power connection.

Table 3 lists the operational conditions that force the analog outputs to their limits regardless of ambient gas concentrations.

Sensor Calibration

The KCO-NO2 must be calibrated at least every six months to maintain the specified accuracy. Calibration entails individually exposing each of the sensors to two gases of  precisely known concentrations (See Table 8) so the measurement system can compensate for changes in the sensor’s sensitivity. The UCK-3 kit is available at Kele.com. Both sensors first use the same zero gas cylinder for zero calibration, but then each sensor uses a different span gas cylinder for the span calibration.

A ‘calibration cap’ is required to cover the sensor body and form an isolated pocket at the sensor that is filled with the appropriate calibration gas supplied from cylinders of compressed gas through a regulator connected to it by typically 1/4 “ OD gas tubing. Refer to the documentation for the calibration kit you are using for instructions on how to assemble and operate its gas supply components. Each sensor must be sequentially calibrated with two different gases. The Zero gas is the same for both sensors and is used for the ‘zero’ calibration, which must be done first. The ‘span’ gas is different for each sensor and used for the ‘span’ calibration which MUST be done ONLY AFTER a successful zero calibration. Each calibration is started with one of the two calibration buttons (ZERO and SPAN) for each sensor module as shown in Figure 9. During calibration and for a period thereafter, the analog outputs are forced to 4 mA and the alarm relays are both deactivated to avoid spurious alarm conditions from residual span calibration gas that has not yet dissipated from the sensor.

Figure 9: Location of Calibration Controls. CO is green; NO2 is yellow.

Calibration Gases

The table below shows the calibration gases required to calibrate the KCO-NO2.

BOTH

|

Zero Gas

| Air (18% to 21% O2, balance N2) Often called “zero air” or “clean air”|

GAS-02-18

CO| Span Gas| 25.0 ppm CO, balance air| GAS-CO-25
NO2| Span Gas| 5.0 ppm NO2, balance air| GAS-NO2-5

A calibration kit UCK-3 is available from Kele.com.

Calibration Procedure

The procedure shown in Table 8 MUST be done twice for each sensor. First it is done as a zero calibration using the zero gas and only after a SUCCESSFUL zero calibration has been completed, the same procedure below is done again as a span calibration using the span gas required for the sensor being calibrated.

The progress and status of the calibration process is indicated by the color and flash-state of the front panel LED for the sensor being calibrated. These LEDs are located at the edge of the main board adjacent to the ‘POWER’ connector. The CO sensor’s LED (LED1) is above the power connector; the NO2 sensor’s LED (LED2) is below the power connector.

A successful calibration MUST be acknowledged within 1 minute of completion,
while the sensor’s status LED is still blinking green. IF NOT ACKNOWLEDGED, THE CALIBRATION WILL NOT BE APPLIED.

For each calibration proceed as follows:

Apply the appropriate calibration gas to the sensor using a calibration cap, following the instructions for the calibration kit being used. Start the desired calibration by  pressing either the ‘ZERO’ or ’SPAN’ button of the sensor being calibrated for 3 seconds (see Figure 9). Gas sampling starts immediately, indicated by the sensor’s LED blinking YELLOW. Ensure that the calibration cap covers the sensor completely for the 2 minute sampling period. At the end of the sampling period, the sensor’s status LED blinks GREEN if the calibration was successful or RED if not.

If successful (blinking GREEN):

the calibration completed successfully, but must be accepted by pressing the same button that started the calibration again for 3 seconds while the LED is flashing GREEN. The LED then blinks GREEN/YELLOW for 2 minutes indicating that the calibration was accepted. The cal gas flow can be shut-off as soon as the LED turns GREEN. If not acknowledged within one minute the LED flashes RED/YELLOW indicating that the calibration was not applied.

If NOT successful (blinking RED):

the calibration can be re-started while the LED is blinking RED by pressing the button that started the calibration again for three seconds until the LED again blinks YELLOW. If no button is pressed during the 1 minute of blinking RED, the LED switches to blinking RED/YELLOW for two minutes to indicate that the calibration was NOT applied.

If the span calibration for a sensor fails more than once, and the sensor has been in service for more than a year, the most likely cause is that the sensor’s sensitivity has decreased by more than 20% from its original factory calibration and must be replaced.

Replacement Sensors:

Calibrated sensor modules are available from Kele.

/gas-and-specialty-sensors/gas-calibration/kele/uck-3)

Sensor Module Replacement

If there is an issue with one of the sensor modules, the front panel LED for the corresponding sensor will blink red. The faulty sensor module’s 4-20mA analog signal will output 20 mA (indicating a full scale reading). Additionally, the faulty sensor module’s LED will flash rapidly; this is viewable by opening the enclosure’s front panel. When this occurs, the sensor module must be replaced. Sensors must be installed in the correct location.

• Sensor 1 = CO
• Sensor 2 = NO2

Sensor Errors

The sensors are regularly tested to verify proper operation. If a sensor failure is detected:

1. its front panel LED will blink red.
2. the warning relay will be active.
3. the alarm contact will remain inactive.
4. its analog output will be forced to 20 mA to alert the device monitoring the analog reporting output that the sensor has failed.

When a sensor’s status LED is blinking red, the corresponding sensor is no longer operational and must be replaced.

Field Replacement of Sensor Modules

Sensor modules must be replaced when they reach their End of Life. Care should be taken to ensure the correct sensor modules are placed in the proper location: CO is on top (highlighted in green in Figure 10) and NO2 is in the lower location (highlighted in yellow in Figure 10).

Figure 10: Sensor Module Replacement. CO sensor is green, NO2 is yellow.

To replace a sensor module:

1. Open the device’s front panel.
2. Unplug the device’s power connector (refer to Figure 6).
3. Unplug the affected sensor module by holding the device’s board and pulling the sensor module firmly away (Figure 10).
4. Plug the new sensor module into the vacant location: press the module firmly until the nylon standoff (highlighted in red in Figure 10) at the bottom-left side of the board has been seated properly. Be sure the sensor module is plugged into the proper location.
5. Plug in the sensor’s power connector.
6. Observe that the front panel indicator is no longer flashing red, and then close the enclosure.

NOTE: Placing sensor modules in incorrect locations will not harm the device; but improper gas concentration will be present at the corresponding analog output and the front panel LED indicators.

Warranty

Duration

Limited Warranty and Remedies

Kele warrants to Buyer that for the duration stated in the “Duration” section above from the date of shipment of Products to the Buyer that Products will substantially conform to the product specifications agreed to by DCS. This warranty is not transferable. This warranty does not cover

• Defects due to misuse, abuse, or improper or inadequate care, service or repair of Products;
• Defects due to modification of Products, or due to their alteration or  repair by anyone not authorized by Kele.
• Problems that arise from lack of compatibility between DCS’s Products and other components used with those Products or the design of the product into which Products are incorporated. Buyer is solely responsible for determining whether Products are appropriate for Buyer’s purpose, and for ensuring that any product into which Products are incorporated, other components used with DCS’ Products, and the purposes for which DCS’ Products are used are appropriate and compatible with those Products.

If Kele determines that a returned Product does not conform to this warranty it will, at Kele’s discretion, either repair or replace that Product, and will ship the Product back to Buyer free of charge. At Kele’s option, Kele may choose to refund to Buyer the purchase price for a nonconforming Product instead of repairing or replacing it.

THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESS OR IMPLIED. Kele EXPRESSLY DISCLAIMS ALL IMPLIED WARRANTIES, INCLUDING THE WARRA TIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. NEITHER Kele NOR ANY OF ITS SUPPLIERS IS RESPONSIBLE IN ANY WAY FOR DAMAGE TO A PRODUCT, PROPERTY DAMAGE OR PHYSICAL INJURY RESULTING IN WHOLE OR IN PART FROM (1) IMPROPER OR CARELESS USE, (2) UNAUTHORIZED MODIFICATIONS, OR (3) OTHER CAUSES BEYOND Kele OR ITS SUPPLIERS CONTROL. IN NO EVENT ARE Kele OR ANY OF ITS SUPPLIERS LIABLE TO THE BUYER OR ANY OTHER PERSON FOR COST OF PROCUREMENT OF SUBSTITUTE GOODS, LOSS OF PROFITS, OR FOR ANY OTHER SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES.

Disclaimers

Inspection and Maintenance

In order to maintain the specified accuracy this device, both its sensors must be calibrated at least every 6 months. During calibration the sensitivity of the sensor is compared to its sensitivity during initial factory calibration. If the sensitivity has fallen below the manufacturer’s specification, the sensor has reached the end of its operating life and must be replaced. Contact Kele for a calibrated replacement module.

In harsh environments, or if exposed to concentrations above its rated maximum, a sensor may fail prematurely. During normal operation both sensors are regularly tested to detect common failures. If a failure is detected, the front panel status LED for that sensor will blink red and its concentration- reporting analog output will stay at 20 mA until the sensor is replaced.

Life Safety

This unit is not designed, certified, sold or authorized for use in applications where the failure of this device could be reasonably expected to result in personal injury or death.

NEITHER Kele NOR ANY OF ITS SUPPLIERS IS RESPONSIBLE IN ANY WAY FOR DAMAGE TO A PRODUCT, PROPERTY DAMAGE OR PHYSICAL INJURY RESULTING IN WHOLE OR IN PART FROM (1) IMPROPER OR CARELESS USE, (2) UNAUTHORIZED MODIFICATIONS, OR (3) OTHER CAUSES BEYOND Kele OR ITS SUPPLIERS CONTROL. IN NO EVENT ARE Kele OR ANY OF ITS SUPPLIERS LIABLE TO THE BUYER OR ANY OTHER PERSON FOR COST OF PROCUREMENT OF SUBSTITUTE GOODS, LOSS OF PROFITS, OR FOR ANY OTHER SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES.

References

• kele.com - Building Automation Products and Solutions
• kele.com - Building Automation Products and Solutions

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