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Home » Devices » CO2 concentration » CO2 Meter LB-857

LB-857 - High Carbon Dioxide Concentration Meter and Regulator

  • meter in the range of up to 20% or 100%
  • high-quality CO2 sensor
  • function: CO2 concentration meter, regulator
  • measurement: CO2 (carbon dioxide) concentration
  • measurement method CO2 NDIR
  • measurement result outputs:
    • analogue 0…10 V
    • 2 relays
    • USB
    • RS-485


The basic function of the LB-857 CO2 meter is to measure carbon dioxide concentration in the atmosphere. Additional functions of the CO2 meter/regulator include: signalisation when the set thresholds are breached, regulation connected with the CO2 measurements.

The LB-857 CO2 concentration meter is a stationary device of small dimensions, powered by an external power supply. The meter features modern design, based on the NDIR method (NDIR — non-dispersive infrared). It measures the damping of IR radiation of a specific wavelength emitted by the measured gas; this damping is dependent on the carbon dioxide content in the measured gas. The NDIR method provides for accurate and stable measurement results and many years of trouble-free operation of the CO2 sensor. The CO2 measurement sensor is located inside the instrument, and the measured air may be supplied convectionally to the inside of the instrument, through the openings in the housing.

The sensor is used for CO2 concentration measurement in the range of 0…20% or 0…100%.

This CO2 meter/regulator features a 0…10 V voltage output, proportionally to the measured CO2 concentration, which can be used in many applications.  Two relay outputs may be used for signalling when the alarm states are breached or for threshold regulation in the on/off mode (e.g. ventilation). The value of thresholds controlling the relays, hysteresis and the range of the 0…10 V converter processing are set through one of the built-in interfaces and a specialist LBX application.

The read-out of the carbon dioxide concentration measurements, taken with the CO2 sensor, and introduction of settings is possible via the USB or the RS-485 interface. Selection of the device’s interface is made by correctly setting the configuration jumpers, accessible after the device’s protective cover is removed. The meter is implemented with the MODBUS RTU protocol; the MODBUS address is set with the use of jumpers that are accessible after the device’s protective cover is removed.

CO2 calibration

The user may calibrate the CO2 sensor’s. To this end, the meter must be placed in an area with a pre-determined, constant value of the CO2 concentration; wait a few moments for the measurement to stabilise, and them, by using the pre-determined CO2 concentration meter value introduced in the LBX software, carry out the calibration.

The CO2 sensor may be mounted in the installation location with the use of 2 screws and holes prepared in the bottom part of the housing.

The operating environment of the CO2 sensor is not aggressive. When the device is flooded or if water condenses inside the meter, a malfunction may occur.

Other meters:

The meter may be, for example, used for:

  • gas emissions control in industry;
  • monitoring for safety reasons;
  • Operation monitoring of ventilation systems in various facilities (e.g. offices, livestock buildings; details in an additional description.

Technical Data

CO2 measurement
CO2 sensor type NDIR, built-in
Measurement range of the CO2 volume content 0…20% or 0…100%
CO2 measurement accuracy ±0.2% and ±5% of the measured value
Heating-up time of the meter after powering up 1 minute
Analogue 0…10 V Not insulated, min. load bearing capacity: 1,000 Ohm, the range set the maximum of 0…100% 
Relay 2 outputs, 1A/250V, resistance load, alarm or regulation
Digital interfaces USB, RS-485 (MODBUS RTU 19200/8/1/E)
Operation conditions
Operating temperature range 5…50°C
Air relative humidity range 10…80% — recommended continuous operating conditions, 5…90% — admissible temporary conditions (without water condensation)
Remaining parameters
Power supply 24V AC (15…30 ACV) or 20…45 DC
External dimensions 84 x 84 x 36 mm
Weight approx. 150 g