Gas Sensor GX-CO2-25
€200.84
The active CO₂ sensor with LED display and alarm for indoor air monitoring
The Schabus GX-CO2-25 is an active carbon dioxide sensor for monitoring indoor air quality in occupied rooms. It detects CO₂ from exhaled air and reliably reminds you when ventilation is needed, e.g. in classrooms, offices, daycare centres and meeting rooms. Elevated CO₂ concentrations displace oxygen, are directly related to poor indoor air quality and lead to fatigue, loss of concentration and reduced performance.
An NDIR sensor (infrared spectroscopic) measures the CO₂ concentration from approx. 400 ppm to approx. 5,000 ppm. The pre-alarm is triggered at approx. 1,400 ppm, the main alarm at approx. 2,500 ppm CO₂ (0.25 %vol.). The thresholds are based on the recommendations of health and environmental authorities (TRGS 900, MAK value); the main alarm corresponds to roughly half the MAK value.
The GX-CO2-25 operates independently with a three-colour LED status display, built-in piezo sounder and test button, either as a stand-alone device with a 5 V power supply or as an accessory for the Schabus gas warning devices GX-A1+ and GX-HS. It is low-maintenance and designed for a service life of more than approx. 5 years, depending on ambient conditions.
Important note: The sensor may only be installed in dry indoor rooms and must not be used in potentially explosive atmospheres. The sensor cable must be installed as a fixed surface-mounted cable and must never be run parallel to mains voltage lines. Always observe the prescribed mounting height. Never expose the sensor to pure carbon dioxide, e.g. from catering gas cylinders, as this can permanently impair the accuracy of the evaluation circuit.
Early ventilation reminder with its own alarm
The GX-CO2-25 combines NDIR measuring technology, pre-alarm and main alarm, status display and test button in a compact device.
NDIR measuring technology
Infrared spectroscopic measurement from approx. 400 ppm to approx. 5,000 ppm CO₂, approx. 15 measurements in 10 seconds.
Pre-alarm and main alarm
Pre-alarm at approx. 1,400 ppm, main alarm at approx. 2,500 ppm CO₂. Practical and not overly sensitive.
Three-colour LED status display
Indicates warm-up time, operation, pre-alarm, main alarm and fault. The test button checks the LEDs and the sounder.
Integrated piezo alarm
Acoustic alarm via the built-in piezo sounder, can be acknowledged and automatically silences when the CO₂ concentration decreases.
Accessory for GX-A1+ and GX-HS
Connection via RJ plug. The analogue signal can be further processed, e.g. for ventilation systems, window openers or building management systems.
Also operable with power supply
As an active sensor with stabilised 5 V power supply or USB power supply, it can also be used mobile and without a gas warning device.
Accuracy ± 50 ppm / ± 3 % / ± 1 digit
Digital-to-analogue evaluation, quasi-linear. Operating voltage 5 V DC, max. 320 mA.
−10 °C to +50 °C
Operating range −10 °C to +50 °C, humidity 5–90 % RH (non-condensing), protection class IP 20.
What’s in the box
The sensor is supplied ready with sensor cable and mounting material.
- Gas sensor GX-CO2-25
- Sensor cable, 3-core, white, with RJ plug (2.5 m)
- Mounting material (screws, wall plugs)
- Operating instructions
How the GX-CO2-25 is constructed
The GX-CO2-25 consists of a compact housing with NDIR sensor, evaluation electronics, status display, test button and permanently connected sensor cable with RJ plug.
Housing
The housing measures 79 × 60 × 41 mm (H × W × D) and has protection class IP 20. It has ventilation slots so that room air can reach the sensor. The device must not be opened; mechanical stress, impacts and dropping must be avoided.
NDIR sensor with evaluation electronics
The infrared spectroscopic sensor measures CO₂ from approx. 400 to approx. 5,000 ppm. The evaluation circuit converts the measured concentration into a voltage, the so-called sensor voltage, which is understood by the gas warning devices GX-A1+ and GX-HS.
LED status display
The LED indicates the status in colour: warm-up time, operation, pre-alarm, main alarm or fault. The device is labelled Operate, Preheat and Alarm.
Test button and piezo sounder
The test button checks the LEDs and the sounder. When pressed, the buzzer sounds continuously; when held for several seconds, the sensor voltage rises to approx. 3 V and the alarm is triggered.
Sensor cable with RJ plug
The white, 3-core sensor cable (Ø 3.5 mm, 3 × 0.75 mm²) is 2.5 m long. Wire colours: brown = +5 V operating voltage, white = sensor voltage, green = ground. An RJ plug is fitted at the end.
Alarm levels and sensor voltage
The sensor converts the CO₂ concentration into a voltage. With fresh air (approx. 400 ppm, sensor zero point) 0.4 V is output; the highest voltage is around 3.3 V.
Pre-alarm
From approx. 1,400 ppm CO₂. LED flashes alternately green and red, the buzzer emits short tones with long pauses. The GX-A1+ switches to pre-alarm at rising voltage from 2.0 V.
Main alarm
From approx. 2,500 ppm CO₂. LED lights green and flashes red every ½ second, the buzzer emits longer tones with short pauses. The GX-A1+ switches to main alarm from 2.5 V.
Debouncing against false alarms
The alarm on the gas warning device is only triggered after several measurements. The warning device responds slightly more slowly in pre-alarm than the sensor; this is not a fault.
Response time
The sensor needs up to 90 seconds to adjust to a higher value. When the CO₂ concentration decreases, several minutes until a lower value are usual.
With gas warning device or stand-alone with power supply
On GX-A1+ or GX-HS
The sensor is operated as an accessory with the gas warning devices GX-A1+ (Art. No. 300892) and GX-HS (Art. No. 400200). Gas warning device and sensor are always put into operation together. Connection details can be found in the operating instructions of the warning device.
Stand-alone with power supply
If you do not need to switch a load or transfer data to a building management system, the sensor runs on a stabilised 5 V DC supply. The USB interface of a computer or a USB power supply is also possible; Schabus offers suitable USB-RJ connection cables.
Placement, mounting and connection
The sensor must be correctly positioned to ensure proper functioning of the warning device.
Placing the sensor
- To monitor a suspected CO₂ source, mount the sensor 30–40 cm above the floor, but no more than 4 m from the source. Escaping CO₂ is heavier than air and sinks to the floor.
- To monitor general indoor air quality, mount the sensor 140–160 cm above the floor, but not near a suspected CO₂ source.
- Install the sensor only in dry indoor rooms that are regularly occupied by people.
Unsuitable locations
- Places that could prevent alarm triggering in the event of a gas leak, e.g. behind curtains, in cabinets or behind stacked boxes
- Directly above a cooker/stove or combustion appliance or above a sink
- Next to doors, windows, ventilation, fans, air conditioning, etc.
- Areas where dust or dirt can put the sensor out of operation
- Areas with constantly high CO₂ concentrations by default
- Areas with constantly high or condensing humidity
- Potentially explosive atmospheres
Connecting the sensor
- Cable assignment: brown = +5 V operating voltage (terminal 1 on GX-A1+, terminal 22 on GX-HS), white = sensor voltage (terminal 2 on GX-A1+, terminal 23 on GX-HS), green = ground (terminal 3 on GX-A1+, terminal 24 on GX-HS).
- Install the sensor cable as a fixed surface-mounted cable and never run it parallel to mains voltage lines.
- To extend the sensor cable, use a 3-core cable: with 3 × 0.75 mm² max. 10 m, with 3 × 1.5 mm² max. 20 m total length. At the transfer point at least 5 V ± 0.1 V must be present; this must be strictly observed.
Commissioning: After applying the supply voltage, the sensor electronics perform a self-test: the yellow LED flashes briefly and the buzzer sounds briefly. The sensor then requires a warm-up time; the gas warning devices GX-A1+ and GX-HS need approx. 5 minutes warm-up time. After a power failure, the self-test and warm-up time are also restarted.
LED function display
- LED flashes green: warm-up time
- LED lights green: sensor is in operation
- LED flashes green / red alternately: pre-alarm (> 1,400 ppm CO₂)
- LED lights green and flashes red every ½ second: main alarm (> 2,500 ppm CO₂)
- LED lights yellow: fault
What to do in the event of an alarm
- Do not unplug the warning device
- Open windows and doors and thoroughly ventilate the room
- Inform other people in the building; all persons should leave the room until the cause has been found and eliminated
- Ideally the relay of the GX-A1+/GX-HS switches on forced ventilation or opens a powered window; check their function in the event of an alarm
- Inspect the room for any sources of fire; CO₂ is also produced during smoke development from fires – in that case all persons must leave the room
- Eliminate the cause of the gas release; if in doubt, seek professional help
- For reference: 2,500 ppm allows first physiological impairments to be perceived, but is still far from life-threatening; the MAK in offices is e.g. 5,000 ppm (exposure over 8 hours)
During commissioning in higher gas concentrations or with several people in small rooms, the sensor may alarm immediately after a short warm-up time. Unplug it, take it into fresh air for about 15 minutes, ventilate the room and put the sensor back into operation.
Function test, alarm test and replacement
Function test with exhaled air
Normal exhaled air contains approx. 4 % CO₂. Hold your face 15–20 cm in front of the sensor, continue breathing normally and gently blow on the front when exhaling; keep moisture away. The sensor voltage rises steadily up to the pre-alarm and, due to inertia, possibly up to the main alarm. The alarm then only falls again after a much longer time.
Alarm test
Press the test button for several seconds: the sensor voltage rises to approx. 3 V, red and green LEDs light, GX-A1+/GX-HS trigger an alarm which you must acknowledge separately on the gas warning device. This also completes the simple function test of the gas warning device.
Recommended interval
The simple test should be carried out every 6 months. Regularly free the sensor of dust by briefly blowing and protect it from moisture.
Replacement and factory inspection
Replace the sensor regularly and after 5 years at the latest. The date (month/year) for the next sensor inspection is marked on the sensor; for factory inspection send it to Elektrotechnik Schabus GmbH & Co. KG, Stephanskirchen.
Manufacturer’s notes
- Read the operating instructions carefully before mounting and commissioning and keep them
- Product and packaging material are not toys and must be kept away from children and pets
- Protect from extreme temperatures, direct sunlight, strong impacts, high humidity, wetness, flammable gases, vapours and solvents
- Do not use in potentially explosive atmospheres
- Always observe the mounting height; never run the sensor cable parallel to mains voltage lines
- Clean only with a dry linen cloth; if heavily soiled, slightly dampened; do not use solvent-based cleaning agents
- Intended for dry indoor rooms with residential-like use: living areas, sales areas, rooms of small businesses
- The manufacturer is not liable for damage or losses resulting from the failure to give an alarm signal
- The CE declaration is available for download on the manufacturer’s website
Matching accessories and compatible devices
LIYY control cable (Art. No. 300780)
Control cable for extending the sensor cable; observe the permissible minimum cross-sections and lengths.
Gas warning device GX-A1+ (Art. No. 300892)
Compatible gas warning device to which the GX-CO2-25 is connected as an external sensor. To be ordered separately.
Gas warning device GX-HS (Art. No. 400200)
Compatible gas warning device to which the GX-CO2-25 is connected as an external sensor. To be ordered separately.
Warranty, guarantee and disposal
The device is covered by the statutory warranty of at least 2 years in the EU. The manufacturer Elektrotechnik Schabus additionally offers a 5-year guarantee that can be registered online. Repair and spare parts are available directly from the manufacturer, also beyond the statutory warranty. In the event of a defect, please contact the manufacturer; within Germany they arrange free collection of the parcel.
The device does not belong in household waste. The crossed-out wheeled bin symbol reminds you to use the take-back systems for waste electrical and electronic equipment (WEEE No. DE91394868).
Why the GX-CO2-25 is suitable
Early warning
Pre-alarm from approx. 1,400 ppm, main alarm from approx. 2,500 ppm CO₂.
Active and independent
LED, piezo alarm and test button, usable even without a warning device.
Flexible use
On GX-A1+, on GX-HS or on a 5 V power supply, also mobile.
NDIR technology
Infrared spectroscopic measurement, low-maintenance, service life > approx. 5 years.
Simple testing
Function test with exhaled air, alarm test via the test button.
Compact
79 × 60 × 41 mm, mounting material included.
Areas of application
- Classrooms and schools
- Offices and meeting rooms
- Kindergartens and daycare centres
- Seminar rooms and conference rooms
- Libraries and co-working spaces
- Common rooms and canteens
- Event rooms
- Monitoring of a suspected CO₂ source in dry indoor rooms
- Control of ventilation systems, window openers or building management systems via GX-A1+ / GX-HS
- Mobile use as an active sensor with 5 V power supply
The Schabus GX-CO2-25 reliably reminds you to ventilate – wherever people regularly spend time in indoor rooms.
Frequently asked questions
What is the GX-CO2-25 used for?
It monitors indoor air quality in occupied rooms and reminds you to ventilate when the CO₂ concentration is elevated, e.g. in classrooms, offices, daycare centres and meeting rooms.
At which CO₂ levels does the sensor alarm?
The pre-alarm is triggered at approx. 1,400 ppm, the main alarm at approx. 2,500 ppm CO₂. The thresholds are based on the recommendations of health and environmental authorities (TRGS 900, MAK value).
Can the sensor be operated without a gas warning device?
Yes. As an active sensor it can also be used mobile with a stabilised 5 V power supply or USB power supply. Switching a load or transfer to a building management system is then not available.
Which gas warning devices are compatible?
The GX-CO2-25 is an accessory for the Schabus gas warning devices GX-A1+ (Art. No. 300892) and GX-HS (Art. No. 400200). Connection details can be found in their operating instructions.
At what height should I mount the sensor?
For a suspected CO₂ source 30–40 cm above the floor, max. 4 m from the source, because escaping CO₂ is heavier than air. For general indoor air quality 140–160 cm above the floor, not near a CO₂ source.
Where must the sensor not be mounted?
Not behind curtains, in cabinets or behind covers, not above a cooker or sink, not next to doors, windows, ventilation or air conditioning, not in dusty, permanently humid or potentially explosive areas, and not where constantly high CO₂ levels already prevail.
Can I extend the sensor cable?
Yes, with a 3-core cable, e.g. the LIYY control cable (Art. No. 300780): with 3 × 0.75 mm² up to max. 10 m, with 3 × 1.5 mm² up to max. 20 m total length. At the transfer point at least 5 V ± 0.1 V must be present. Install the cable as a fixed surface-mounted cable, never parallel to mains voltage lines.
Why does the sensor alarm immediately after commissioning?
In higher gas concentrations or with several people in small rooms the sensor may alarm immediately after a short warm-up time. Unplug the sensor, take it into fresh air for about 15 minutes, ventilate the room and put it back into operation.
How do I test the sensor?
With normal exhaled air (approx. 4 % CO₂): hold your face 15–20 cm in front of the sensor and gently blow on the front when exhaling. For an alarm test press the test button for several seconds. The simple test is recommended every 6 months. Never expose the sensor to pure carbon dioxide.
How long does the sensor last?
The service life is more than approx. 5 years, depending on ambient conditions. The manufacturer recommends replacing the sensor regularly and after 5 years at the latest. The date for the next sensor inspection is marked on the sensor.
How do I clean the sensor?
Remove dust by briefly blowing, wipe the housing with a dry linen cloth; if heavily soiled, slightly dampened. Do not use solvent-based cleaning agents and keep moisture away.
How long is the warranty?
The statutory warranty of at least 2 years in the EU applies. In addition, the manufacturer Schabus offers a 5-year guarantee that can be registered online.
Questions about the GX-CO2-25 CO₂ sensor?
Our support team in Germany will advise you free of charge on selection, installation and configuration.
GX-CO2-25 Gas Sensor
The GX-CO2-25 is a CO₂ sensor with NDIR infrared technology for precise measurement of carbon dioxide in indoor environments. The service life is approximately 5 years, depending on ambient conditions.
Technical Data
- Operating voltage: 5 V DC, max. 320 mA
- Operating range: -10 °C to +50 °C
- Storage temperature: -20 °C to +60 °C
- Humidity (ambient): 5–90 % RH, non-condensing
- Measuring range: approx. 400 ppm to approx. 5,000 ppm CO₂
- Measuring principle: NDIR – infrared spectroscopic
- Measuring frequency: approx. 15 measurements in 10 seconds
- Output: digital to analog, quasi-linear
- Accuracy: ±50 ppm / ±3 % / ±1 digit
- Service life: approx. 5 years, depending on environmental conditions
- Protection class: IP 20
- Cable length: 2.5 m
- Cable diameter: 3.5 mm
- Dimensions (H×W×D): 79 × 60 × 41 mm
Manufacturer information:
Electrical engineering Schabus GmbH & Co. KG
Baierbacher Straße 150
83071 Stephanskirchen
Germany
Telephone: +49 80 36 / 674 979 – 0
Email: info@elektrotechnik-schabus.de
Responsible person:
Didactum® Security GmbH
Im Mühlenfeld 4
48163 Münster
Deutschland
Fon:
(+49) 250 19 71 63 54 / (+49) 171 33 11 577
Email: info@didactum-security.de
