Kele K-O2 User manual

Kele, Inc. • 3300 Brother Blvd. • Memphis, TN 38133
Revision: 5/20/2022 www.kele.com 90-0007-00A
K-O2-xx
Oxygen Sensor/Transmitter
and
Two-Stage Alarm Controller
User’s Manual
K-O2-H5 (5 year sensor)
K-O2-H10 (10 year sensor)
K-O2-S5 (5 year sensor)
K
-
O2
-
S10
(10 year sensor)

K-O2 Oxygen Sensor
Kele, Inc. • 3300 Brother Blvd. • Memphis, TN 38133 Page: ii
www.kele.com
TABLE OF CONTENTS
Product Ordering Information ....................................................................................................................................... 1
1 Specifications ......................................................................................................................................................... 2
2 Mechanical Installation .......................................................................................................................................... 3
2.1 Enclosure Dimensions .......................................................................................................................................... 4
3 Electrical Installation ............................................................................................................................................. 4
3.1 Analog Output Connections ......................................................................................................................... 4
3.2 Relay Connections ........................................................................................................................................ 4
3.3 Power Connection ........................................................................................................................................ 5
4 Operational Description ........................................................................................................................................ 5
4.1 Special Modes .............................................................................................................................................. 6
4.2 Warning /Ventilation and Alarm Conditions ................................................................................................ 7
4.3 Setting Ventilation and Alarm Thresholds ................................................................................................... 7
4.4 Concentration Reporting .............................................................................................................................. 7
5 Sensor Calibration .................................................................................................................................................. 7
5.1 Calibration Gases ......................................................................................................................................... 9
5.2 Calibration gas connection ........................................................................................................................... 9
5.3 Zero Calibration Procedure ........................................................................................................................ 10
5.4 Span Calibration Procedure ....................................................................................................................... 11
6 Sensor Module Replacement............................................................................................................................... 12
6.1 Field Replacement of Sensor Modules ....................................................................................................... 12
7 Warranty .............................................................................................................................................................. 13
7.1 Duration ..................................................................................................................................................... 13
7.2 Limited warranty and remedies. ................................................................................................................ 13
8 Disclaimers ........................................................................................................................................................... 14
8.1 Inspection and Maintenance...................................................................................................................... 14
8.2 Life Safety ................................................................................................................................................. 14

K-O2 Oxygen Sensor
5/20/2022 Kele, Inc. • 3300 Brother Blvd. • Memphis, TN 38133 Page 1
www.kele.com
PRODUCT ORDERING INFORMATION
This Manual covers the Kele K-O2-xx oxygen concentration sensor family. The family comprises 4 models with
common features and functionality, available in two enclosure styles and two sensor lifetime options as shown in
Table 1.
Description Kele Part Number
Screw down enclosure with 5 year sensor life K-O2-S5
Screw down enclosure with 10 year sensor life K-O2-S10
Lockable, hinged enclosure with 5 year sensor life K-O2-H5
Lockable, hinged enclosure with 10 year sensor life K-O2-H10
Table 1: K-O2 family Part numbers
All K-O2-xx models are shipped with either 5 year life (K-O2-x5) or 10 year life (K-O2-x10) factory calibrated oxygen
concentration sensor modules installed. At the end of sensor life these plug-in, calibrated, easily field-replaceable
sensor modules are available from Kele.
Description Kele Part Number
5 year calibrated replacement sensor module KMOD-O2-25
10 year calibrated replacement sensor module KMOD-O2-50
Table 2: K-O2 Family Replacement Sensor Module Part Numbers
A calibration kit containing the accessories required to calibrate any of the K-O2 family sensors is available from
Kele under the part number UCK-1.

K-O2 Oxygen Sensor
5/20/2022 Kele, Inc. • 3300 Brother Blvd. • Memphis, TN 38133 Page 2
www.kele.com
1 SPECIFICATIONS
Mechanical
Chassis Construction Industrial strength, 18 Ga. Gray powder-coated steel. Pad-lockable
hinged or screw-on cover style available.
Weight 2.0 lbs
Operating Temperature 4 to 40°C
Operating Humidity 15 – 90 %RH, non-condensing
Storage Temperature -20 to 20°C (to minimize sensor degradation)
Case Dimensions (H x W x D) K-O2-Hx: 6.4” x 5.9” x 2.4” (163.5 x 150.8 x 60.7 mm)
K-O2-Sx: 6.3” x 5.8” x 2.1” (160.0 x 147.3 x 52.0 mm)
Sensor Vents Natural ventilation through 18, 0.1” (2.54 mm) diameter vents
External Indicators Tri-color LED indicates operational status of sensor.
Knockouts 4 trade ½” knockouts (1 per side)
Table 3: mechanical Specifications
Electrical
Operating Power Voltage 14 – 30 VAC (RMS) or DC
Isolated power supply; separate transformer not required.
Power Consumption < 5W
Control Relays
2 separate SPDT line-voltage-capable relays for
warning/ventilation and alarm outputs.
UL-rated: 10 Amps max at 120/277 VAC or 30 VDC. (E43203)
Concentration Reporting Output
Isolated, powered 4 – 20 mA current loop output.
4 mA output => 0 % concentration. 20 mA => 25%
Maximum loop resistance: 510Ω
Termination Pluggable screw-terminals for use with 12 AWG or thinner wire
Table 4: Electrical Specifications
Oxygen Sensor (O2)
Sensor Type Galvanic cell
Measurement Range 0 – 25% (by volume)
Analog Output Range 4-20mA (corresponds to 0 to 25%)
Accuracy ±0.3% O2 (typical after calibration)
Calibration Interval 6 Months (to maintain specified accuracy)
Sensor Life K-O2-x5: 5 years (typical)
K-O2-x10: 10 years (typical)
Recommended calibrated Field-
Replaceable Sensor KMOD-O2-25 (5 years) or KMOD-O2-50 (10 years)
Calibration Kit UCK-1 kit
Calibration gases Span (20.9% oxygen, balance nitrogen): Kele PN:GAS-O2-20.9
Zero (100% nitrogen) Kele PN: GAS-N2
Table 5: Oxygen Sensor Specifications

K-O2 Oxygen Sensor
5/20/2022 Kele, Inc. • 3300 Brother Blvd. • Memphis, TN 38133 Page 3
www.kele.com
2 MECHANICAL INSTALLATION
The Model K-O2 is available in two versions of an industrial-strength, 18 Gauge, gray, powder-coated steel
enclosure. The pad-lockable, hinged-cover version is shown in Figure 1 and the removable, screw-down cover
version is shown in Figure 2. All electronics are attached to the front cover. There are trade ½” conduit knock-outs
on all sides for electrical connections. In potentially damp locations the knock-out 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
 Vertically with the status LED in the lower left or lower right corner.
 Horizontally in any orientation.
5. Mounting holes are made for direct wall screws for the surface encountered. (Mounting screws not
provided) or switch box spacing.
Figure 1: Hinged Front Panel Enclosure Dimensions
(K-O2-Hx)
Figure 2: Screw-Down Front Panel Enclosure
Dimensions
(K
-
O2
-
Sx)

K-O2 Oxygen Sensor
5/20/2022 Kele, Inc. • 3300 Brother Blvd. • Memphis, TN 38133 Page 4
www.kele.com
2.1 ENCLOSURE DIMENSIONS
Distance from center
Case Style Mtg hole diameter Horizontal Vertical
K-O2-Hx (Hinged) 5/16” (7.94 mm) 1.25” (31.75 mm) 1.50” (38.10 mm)
K-O2-Sx (Screw-down) 9/32” (7.14 mm) 1.50” (38.10 mm) 1.50” (38.10 mm)
Table 6: Mounting Hole Diameters & Locations
3 ELECTRICAL INSTALLATION
The controller 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 controller are made through screw terminals that can be unplugged for easy
landing of wires. The controller’s enclosure contains conduit knockouts on all sides for flexibility during
installation; refer to Figure 1 and Figure 2 for details and dimensions of the enclosures.
3.1 ANALOG OUTPUT CONNECTIONS
The sensor’s readings are reported at the controller’s powered 4-
20mA analog output connections. Current flows out of the ‘+’
terminal and returns to the ‘-‘ terminal.
The oxygen sensor output is provided at the terminal highlighted in
Figure 3. Analog output connection has polarity as labeled on the
controller silkscreen: care must be taken to ensure proper
connection. To wire the analog output connections:
1. Power down the controller, this can be done by unplugging
the controller power terminal (see Figure 6).
2. Unplug the analog output screw terminal labeled O1.
3. Attach the signal wires, paying close attention to the
polarity.
4. Plug the analog output screw terminal back into the
controller.
3.2 RELAY CONNECTIONS
The controller has two, 10 Amp, 120/277 VAC UL-rated, SPDT dry-
contact relay output connections (shown in Figure 4) that can directly
control loads up to 10 Amps through the normally-open terminal.
The relay connections have three-terminal screw connectors that allow
devices to be wired to the controller in either normally-open (NO) or
normally-closed (NC) configuration. These outputs are activated when
ambient air oxygen concentration falls below the controller threshold
settings (refer to Section 4.2 for more information).
Figure 3: Analog Output
Figure 4: Relay Outputs

K-O2 Oxygen Sensor
5/20/2022 Kele, Inc. • 3300 Brother Blvd. • Memphis, TN 38133 Page 5
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Figure 6: Location of Power Connector
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 only while
the relay output is deactivated: the voltage attached to the NC terminal is removed when the relay output is
activated.
Example wiring diagrams for relay connection are provided in
Figure 5. To wire the Warning/ventilation 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 a supply voltage for the device being attached
to the controller’s relay output to either the NO or NC
location of the screw terminal (see Figure 4).
4. Wire the power input of the device being attached to
the controller’s relay output to the COM location of
screw terminal.
5. Plug the relay output screw terminal back into the
correct location on controller board.
3.3 POWER CONNECTION
The K-O2 has a fully isolated, unpolarized power input; either
AC or DC operating power can be connected in either polarity.
Multiple K-O2 units can operate on the same transformer (up to
its load limit) even when they are not connected with the same
positive/negative or hot/common polarity.
Power connection to the controller is made at the two-terminal
screw connector located at the bottom-right side of the board
(highlighted in Figure 6). Power to the controller can be either
AC or DC voltage; DC voltage can be connected in either polarity
(see Section 1.0 for more details). To wire power:
1. Open the controller’s enclosure and unplug the screw
terminal labeled POWER on the controller 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 controller board: this will cause the
controller to power up and begin operation.
It is recommended that all wired connections are made prior to providing power to the controller.
Figure 5: Example Wiring Diagram for
Normally Open Operation

K-O2 Oxygen Sensor
5/20/2022 Kele, Inc. • 3300 Brother Blvd. • Memphis, TN 38133 Page 6
www.kele.com
Status LED Color Operational Status
Description
Concentration is above
the warning/ventilation
threshold. No relay
outputs are active.
Concentration is below
the warning/ventilation
threshold and above the
alarm threshold.
Warning/ventilation relay
is active.
Concentration is below
the alarm threshold. Both
warning/ventilation and
alarm relays are active.
End of Life warning.
Sensor has reached the
end of its rated service life
and should be replaced.
Relays and analog
outputs continue to
function normally.
Sensor Expired.
Warning/ventilation relay
is active and analog
output is 4 mA.
(refer to Section 7)
Table 7: Front Panel Status LED Indications
During Normal Operation.
4 OPERATIONAL DESCRIPTION
The K-O2 is a two-stage ventilation and alarm controller that senses the oxygen concentration in the ambient
space around it and operates a Warning/Ventilation contact closure that can be used to operate ventilation fans
when reduced levels of oxygen are detected. If the oxygen concentration approaches unsafe levels, a second
contact closure is operated; typically to trigger an alarm.
The gas sensor is a calibrated module that 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 front cover has an LED status indicator that illuminates in different colors to indicate normal (green),
Warning/Ventilation (yellow), and Alarm (red) conditions. Blinking red indicates that the sensor is NOT
operational. While the LED is blinking red, the analog output is delivering 4 mA to indicate the error.
The concentration of oxygen in the ambient air is reported at the controller’s analog current-loop output as
percent by volume. The analog output ranges from 4 to 20mA (refer to Table 4 and Table 5).
4.1 SPECIAL MODES
The K-O2 operates in several modes as shown in Table
9.Table 9: K-O2 Operating Modes
Normal operation is as described above. During standby
mode the sensor is stabilizing and analog output is held at 20
mA.
During span calibration the sensor’s sensitivity is compared
to its sensitivity at initial factory calibration. If its sensitivity
has fallen below manufacturer’s specification the K-O2 goes
into Sensor Expired mode with the analog output held at 4
mA and only the Warning/Ventilation relay activated.
Figure 7: Front Cover Status Led

K-O2 Oxygen Sensor
5/20/2022 Kele, Inc. • 3300 Brother Blvd. • Memphis, TN 38133 Page 7
www.kele.com
Dip switch
Setting
OXYGEN %
Warn Alarm
19.8 19.5
20.0 19.5
20.3 20.0
20.5 20.0
Table 8: Concentration Threshold
Settings.
Mode Front Cover LED Analog Output Relays Actuated Comment
Normal Steady Green,
Yellow or Red 4 – 20 mA Depends on
concentration During normal operation
Standby Various 20 mA NONE During start-up interval or any time during
calibration
EOL
warning
Slow Blinking
Yellow 4 – 20 mA Depends on
concentration
Sensor nearing the end of its rated service
life.
Relays and analog output function normally.
Sensor
Expired Slow Blinking Red 4 mA Warning /
Ventilation
After calibration of expired sensor.
Sensor is no longer operational.
Table 9: K-O2 Operating Modes
4.2 WARNING /VENTILATION AND ALARM CONDITIONS
Two, 10 Amp, 120/277 VAC rated, dry-contact, SPDT relays activate during
warning/ventilation and alarm conditions: refer to Section 3.2 for wiring
information.
When the concentration of oxygen falls below its configured
warning/ventilation threshold, the WARNING/VENTILATION relay output is
activated. When the concentration falls below the alarm threshold, the
controller’s ALARM relay is also activated. When the oxygen concentration
rises above the alarm threshold, the ALARM relay is deactivated; when it rises
above the ventilation threshold the WARNING/VENTILATION relay is also
deactivated.
4.3 SETTING VENTILATION AND ALARM THRESHOLDS
The four, factory-preset pairs of ventilation and alarm levels are shown in
Table 8. Each setting determines both the controller’s warning/ventilation
and alarm thresholds.
The active threshold values are selected by setting the two DIP switches on
the main board (see Figure 8) as shown in the first column of Table 8 for the
desired setting.
4.4 CONCENTRATION REPORTING
In normal mode, oxygen concentration readings from the sensor are
reported by the controller’s powered 4 – 20mA current loop output. The
output connector location is shown in Figure 6. Output scaling is as shown
in Table 5.
O2
Federal OSHA Personal Exposure Limit (PEL) . 19.5 %
Figure 8 DIP Switch Locations

K-O2 Oxygen Sensor
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5 SENSOR CALIBRATION
The sensitivity of the galvanic oxygen sensor used on the K-O2 series decreases as the sensor ages. Over the
sensor’s lifetime its accuracy decreases by about 30%. Without intervening calibrations, the sensor will typically
indicate about 14.7 % oxygen concentration in fresh air after 5 (for the K-O2-x5) or 10 (for the K-O2-x10) years.
Required calibration frequency depends on the accuracy requirement of the application. To maintain the accuracy
specified in Table 5 over the full operating range of the K-O2 series, a full calibration interval of 6 months is
recommended. Annual calibration will typically maintain an accuracy within about 0.5% O2 (for K-O2-x5) and
about 0.3% O2 (for K-O2-x10).
For best accuracy, the full two-step calibration process that provides the sensor module with oxygen-free ‘zero’
gas, and then a 21% ‘span’ gas is required. Two calibration buttons (ZERO and SPAN) are provided on the main
board to initiate each calibration operation as shown in Figure 8.
For applications between 18% and 21% oxygen, a span-only calibration is often adequate and requires no
calibration gas. All that’s required is the certainty of fresh air around the sensor. For accuracy at lower oxygen
percentages, a zero calibration before the span calibration is recommended.
To perform a gas-less span calibration: follow the procedure in section 5.4, ignoring all instructions regarding the
application or removal of calibration gas or fittings.
The ‘sensor expired’ test will be performed at the end of a span calibration. If the sensor’s sensitivity has fallen
below manufacturer’s end-of-life specification, the K-O2 goes into Sensor Expired mode with the front cover LED
slowly blinking RED, the analog output at a constant 4 mA and the warning/ventilation relay activated. The
oxygen sensor is no longer operational and must be replaced (See section 6).
The status of the calibration process is indicated by the flash pattern of the front cover LED as shown below.
Blinking Green Successful sampling. Waiting for user to confirm cal
gas removal.
Blinking Red Failed calibration attempt. Waiting for user to
acknowledge with either a re-try or an exit.
Green/Yellow During ambient equilibration period after successful
calibration. New calibration is applied.
Red/Yellow
During ambient equilibration period after failed
sampling. Old calibration is unchanged.
Table 10: Meaning of Status LED Blink Patterns During Calibration.