Vaisala CO₂ Probe GMP343 Vaisala CO₂ Probe GMP343
Vaisala CO₂ Probe GMP343
Vaisala CO₂ Probe GMP343
Vaisala CO₂ Probe GMP343

Vaisala GMP343 CO₂ Probe for Outdoor and Ecological Measurement

Vaisala GMP343 CO₂ Probe for Outdoor and Ecological Measurement

The Vaisala GMP343 is a rugged, high-accuracy carbon-dioxide probe for outdoor monitoring, ecological research, soil respiration, plant-growth chambers and demanding OEM applications.

  • Selectable CO₂ ranges from 0–1000 ppm to 0–2%
  • Diffusion-aspirated or flow-through sampling models
  • Accuracy up to ±(3 ppm + 1% of reading)
  • Temperature, pressure, humidity and oxygen compensation
  • RS-232, RS-485, 4–20 mA, 0–2.5 V or 0–5 V outputs
  • Raw and numerically filtered measurement data
  • IP67 probe housing with the cable connected
  • Compatible with MI70 for portable display and logging

Accurate CO₂ Measurement in Demanding Environments

The Vaisala GMP343 is designed for high-quality carbon-dioxide measurements in outdoor, ecological and research applications. Typical uses include ambient CO₂ monitoring, soil respiration, greenhouse-gas monitoring networks, plant-growth chambers, ecosystem studies and custom OEM systems.

The probe uses Vaisala CARBOCAP® single-beam, dual-wavelength non-dispersive infrared technology with no moving parts. It can provide both raw and filtered measurement data and compensate for temperature, pressure, relative humidity and oxygen concentration.

Choose the range before ordering: GMP343 is supplied with a defined CO₂ measurement range. Select the lowest range that safely covers the expected maximum concentration so the system retains suitable accuracy and output resolution.

Select the GMP343 Measurement Range

Range optionSpecified accuracy at +25 °C and 1013 hPaTypical starting point
0–1000 ppm ±(3 ppm + 1% of reading) Ambient atmospheric monitoring and small concentration changes
0–2000 ppm ±(5 ppm + 2% of reading) Elevated ambient conditions and controlled chambers
0–3000 ppm ±(5 ppm + 2% of reading) Research systems with moderate CO₂ enrichment
0–4000 ppm ±(5 ppm + 2% of reading) Ecological and chamber measurements requiring additional range
0–5000 ppm ±(5 ppm + 2% of reading) Soil, chamber and equilibrium-sampling applications
0–2% CO₂ ±(5 ppm + 2% of reading) Higher-concentration ecological and OEM measurements

Accuracy below 200 ppm is not specified for the 0–2% range. Expected peaks should be considered carefully in soil and ecosystem studies because concentrations can exceed a narrow ambient range.

Diffusion or Flow-Through Sampling?

Selection pointDiffusion modelFlow-through model
How gas reaches the sensor Gas diffuses through the installed filter A pump or process flow carries sample gas through the probe
Best suited to Ambient air, direct exposure, chambers and protected outdoor installations Sampling lines, closed loops, equilibrium sampling and controlled gas delivery
Response Depends strongly on filter and output averaging Depends on sample flow, tubing volume and averaging
Installation priority Weather protection, free gas exchange and representative location Leak-tight tubing, stable flow, low dead volume and controlled pressure
Calibration arrangement Optional GMP343ADAPTER applies reference gas to the diffusion model Reference gas can be introduced through the sample path

Response-Time Examples

ConfigurationAveragingApproximate T90 response
Diffusion model with filter 0 seconds 75 seconds
Diffusion model with filter 30 seconds 82 seconds
Diffusion model without filter 0 seconds Less than two seconds
Flow-through model at 0.3 l/min 0 seconds 26 seconds
Flow-through model at 1.2 l/min 0 seconds Eight seconds

System response is also affected by tubing length, internal volume, pump performance, filters and the sampling method. Evaluate the complete measurement system rather than the probe response alone.

Environmental Compensation

InfluenceGMP343 capabilityApplication guidance
Temperature Internal temperature measurement for continuous compensation Use when outdoor or chamber temperature changes during measurement
Pressure User-configurable compensation over 700 to 1300 hPa Provide actual pressure for accurate measurements across weather or altitude changes
Relative humidity User-set humidity compensation Update the value or system input when water-vapour concentration changes materially
Oxygen User-set oxygen compensation Use the actual background-gas composition for controlled or unusual atmospheres

Electrical and Mechanical Specifications

SpecificationGMP343
Operating voltage 11 to 36 V DC
Power without optics heating Less than 1 W
Power with optics heating Less than 3.5 W
Current output 4–20 mA, 14-bit resolution
Voltage output 0–2.5 V or 0–5 V
Digital outputs RS-232 or two-wire RS-485 using ASCII communication
Operating temperature −40 to +60 °C
Operating pressure Below 5 bar
Flow-through gas flow 0 to 10 l/min
Housing Anodized aluminium
Housing protection IP67 with cable attached
Diffusion-filter protection IP65 with standard weather filter or IP66 with sintered PTFE filter
Connector M12, 8-pin
Probe weight Approximately 360 g

Typical GMP343 Applications

ApplicationRecommended arrangementImportant consideration
Ambient outdoor CO₂ Diffusion model with suitable weather protection Avoid local exhaust sources and solar-heating bias
Greenhouse-gas monitoring network Permanent protected installation with digital data collection Define calibration, data quality and maintenance procedures across all sites
Soil respiration Diffusion probe with horizontal or vertical soil-adapter kit Select range for expected seasonal peaks and evaluate optics-heating influence
Equilibrium sampling Flow-through probe in a closed circulation loop Control leaks, membrane response, condensation, tubing volume and pump flow
Plant-growth chamber Diffusion or flow-through model according to chamber design Keep away from direct CO₂ injection and verify chamber mixing
OEM and research system Selected range and analogue or serial output Document compensation settings, filtering and communication protocol

Vaisala GMP343, GMP252 or GMP251?

Selection pointGMP343GMP252GMP251
Main purpose High-accuracy outdoor, ecological and research measurement Compact ppm-level industrial and OEM measurement Percentage-level industrial and controlled-atmosphere measurement
Ranges Selectable 0–1000 ppm through 0–2% 0–10,000 ppm; up to 30,000 ppm with reduced accuracy 0–20% CO₂
Sampling Dedicated diffusion or flow-through models Diffusion or optional flow-through accessories Diffusion or optional flow-through accessories
Lowest-range accuracy ±(3 ppm + 1% of reading) on 0–1000 ppm version ±40 ppm from 0 to 3000 ppm ±0.1% CO₂ at 5% CO₂
Outputs 4–20 mA, voltage, RS-232 or RS-485 ASCII Current, voltage, Modbus RTU or Vaisala protocol Current, voltage, Modbus RTU or Vaisala protocol
Transmitter platform Standalone; MI70-compatible Standalone or Vaisala Indigo transmitter Standalone or Vaisala Indigo transmitter
Choose this model when Outdoor accuracy, ecological sampling or research flexibility is the priority A compact modern ppm-level probe with Indigo integration is required Normal concentration is percentage-level
Product information GMP343 is detailed on this page Explore Vaisala GMP252 Explore Vaisala GMP251

Output and Accessory Selection

RequirementSelectionApplication note
Controller analogue input 4–20 mA, 0–2.5 V or 0–5 V Match the probe range and receiving-system scaling
Computer or serial logger RS-232 or RS-485 GMP343 uses ASCII communication; confirm protocol compatibility
Portable display and logging MI70 with DRW216050SP cable Useful for in-situ measurement, setup and data logging
Outdoor diffusion measurement GMP343FILTER or sintered PTFE filter 215521 Select protection according to precipitation and contamination exposure
Soil measurement Horizontal kit 215519 or vertical kit 215520 Choose orientation and range according to the research method
Reference-gas calibration GMP343ADAPTER for diffusion model Apply certified gas with a controlled, documented procedure
Fixed mounting GMP343BRACKET or GMP343FLANGE Provide mechanical support and service access

Calibration and Data Quality

GMP343 is factory calibrated at multiple CO₂ and temperature points. Its multipoint calibration function supports up to eight user-defined points when an application requires site-specific recalibration.

  • Use certified gases appropriate to the selected measurement range and uncertainty target.
  • Confirm temperature, pressure, humidity and oxygen compensation during calibration.
  • Allow the probe, filter, tubing and reference gas to stabilise before recording each point.
  • Record raw and filtered data settings so results remain comparable between systems.
  • Set verification frequency according to environmental severity and required data quality.
  • Retain as-found results, calibration coefficients, reference certificates and maintenance records.

Vaisala GMP343 Supplier and Technical Support in Malaysia

Seacom Process Instruments supplies and supports the Vaisala GMP343 CO₂ Probe in Malaysia for ambient monitoring, ecological research, soil respiration, greenhouse-gas studies, plant-growth chambers and demanding OEM applications.

Our team can help select the CO₂ range, diffusion or flow-through model, analogue or serial output, cable length, filter, weather protection, soil adapter and calibration accessories. We can also review sampling-system design, environmental compensation, commissioning and calibration planning.

Selecting a GMP343 configuration? Send us the normal and maximum CO₂ concentration, sampling method, temperature, pressure, humidity, oxygen level, installation environment, output, cable length and data-quality requirement.

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Specific References

12 other products in the same category:

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CO₂ Probe GMP251

Vaisala GMP251 Percentage-Level CO₂ Probe

Vaisala GMP251 Percentage-Level CO₂ Probe

The Vaisala GMP251 is an intelligent probe for stable percentage-level carbon-dioxide measurement in incubators, controlled-atmosphere storage and demanding industrial applications.

  • CO₂ measurement range from 0 to 20% CO₂
  • Accuracy of ±0.1% CO₂ at 5% CO₂
  • Compensation for temperature, pressure, humidity and oxygen
  • Heated sensor head helps prevent condensation
  • 0–20 mA, 4–20 mA, 0–5 V, 0–10 V and RS-485 output options
  • Standalone Modbus RTU operation or connection to an Indigo transmitter
  • Compatible with Vaisala Indigo80 and Insight PC software
  • IP65 probe body with traceable calibration certificate
CO₂, Humidity and Temperature Transmitter GMW80 series

Vaisala GMW80 Series CO₂, Humidity and Temperature Transmitters

Vaisala GMW80 Series CO₂, Humidity and Temperature Transmitters

The Vaisala GMW80 Series provides dependable, cost-efficient room measurement for demand-controlled ventilation and indoor air-quality applications.

  • CO₂ measurement ranges up to 2000 or 5000 ppm, depending on model
  • Temperature measurement from 0 to +50 °C on selected models
  • Optional relative-humidity measurement from 0 to 95 %RH
  • Voltage, current, relay, Pt1000 and Modbus RTU options
  • Display or colour CO₂ indicator available on selected models
  • Stable Vaisala CARBOCAP® technology for continuously occupied buildings
  • Quick installation with correct CO₂ readings immediately after start-up
Vaisala Handheld CO₂ Meter GM70

Vaisala GM70 Handheld CO₂ Meter – Discontinued

Vaisala GM70 Handheld CO₂ Meter – Discontinued

The Vaisala GM70 was a portable carbon-dioxide meter for diffusion measurements, pump sampling, data logging and field checking fixed CO₂ instruments.

  • Discontinued product; not recommended for new purchases
  • GMP221 probes for percentage-level CO₂ up to 20%
  • GMP222 probes for ppm-level CO₂ up to 10,000 ppm
  • GMH70 diffusion handle or GM70PUMP sampling system
  • MI70 indicator with numerical, graphical and logging functions
  • Used for field checking compatible fixed Vaisala CO₂ instruments
  • Use Vaisala Indigo80 for new portable measurement systems
CO₂ Probe GMP252

Vaisala GMP252 PPM-Level CO₂ Probe

Vaisala GMP252 PPM-Level CO₂ Probe

The Vaisala GMP252 is an intelligent standalone probe for stable ppm-level carbon-dioxide measurement in demanding HVAC, refrigeration, agriculture and industrial applications.

  • CO₂ measurement range from 0 to 10,000 ppm
  • Measurement up to 30,000 ppm with reduced accuracy
  • Accuracy of ±40 ppm from 0 to 3000 ppm
  • Compensation for temperature, pressure, humidity and oxygen
  • Heated sensor head helps prevent condensation
  • 0–20 mA, 4–20 mA, 0–5 V, 0–10 V and RS-485 output options
  • Standalone Modbus RTU operation or connection to an Indigo transmitter
  • Compatible with Vaisala Indigo80 and Insight PC software
Duct Mounted CO2 Transmitter GM20

Vaisala GMD20 Duct-Mounted CO₂ Transmitter – Discontinued

Vaisala GMD20 Duct-Mounted CO₂ Transmitter – Discontinued

The Vaisala GMD20 Series was designed for carbon-dioxide measurement inside ventilation ducts and demand-controlled ventilation systems.

  • Discontinued legacy product; not recommended for new projects
  • Nominal CO₂ measurement range from 0 to 2000 ppm
  • GMD20 without display and GMD20D with local display
  • 0–20 mA, 4–20 mA and 0–10 V analogue outputs
  • Optional relay or LonWorks® interface on applicable configurations
  • IP65 electronics enclosure for duct installations
  • Use Vaisala GMD110 for new installations
Duct Mounted CO2 Transmitter GMD10

Vaisala GMD110 High-Accuracy Duct CO₂ Transmitter

Vaisala GMD110 High-Accuracy Duct CO₂ Transmitter

The Vaisala GMD110 measures carbon dioxide directly inside ventilation ducts for precise HVAC control and demand-controlled ventilation.

  • CO₂ measurement range from 0 to 10,000 ppm
  • Accuracy of ±40 ppm from 0 to 3000 ppm
  • 4–20 mA, 0–5 V, 0–10 V or Modbus RTU output options
  • Analogue scaling of 0–2000, 0–5000 or 0–10,000 ppm
  • Fast response with less than two minutes to full specification
  • Heated CARBOCAP® sensor head helps prevent condensation
  • IP65 enclosure for demanding duct installations
  • Traceable calibration certificate included
Vaisala Transmitter Indigo300

Vaisala Indigo300 Industrial Transmitter

The Vaisala Indigo300 is a rugged industrial transmitter for one Vaisala Indigo-compatible smart probe, providing local measurement display and up to three configurable analog outputs.

Its corrosion-resistant IP66 metal enclosure, flexible probe mounting and interchangeable probe design make Indigo300 suitable for humidity, temperature, dew point, CO2, moisture in oil and other demanding industrial measurements.

Long Range Wireless Data Logger (CMS, FDA Approved) RFL100

Vaisala RFL100 Wireless Data Logger and AP10 Access Point

Vaisala RFL100 Wireless Data Logger and AP10 Access Point

The Vaisala RFL100 uses secure, long-range VaiNet wireless technology to monitor temperature, relative humidity and carbon dioxide with the AP10 Access Point and viewLinc Continuous Monitoring System.

  • At least 50 m typical indoor wireless range
  • Up to 32 RFL100 data loggers per AP10
  • 30 days of local measurement memory
  • Approximately 18 months of battery operation for temperature and humidity monitoring
CO2, Temperature and Humidity Transmitter Series GMW90

Vaisala GMW90 Series CO₂, Temperature and Humidity Transmitters

Vaisala GMW90 Series CO₂, Temperature and Humidity Transmitters

The Vaisala GMW90 Series provides stable wall-mounted carbon-dioxide and temperature measurement, with optional humidity, for demanding HVAC and building-automation applications.

  • Carbon-dioxide measurement from 0 to 5000 ppm
  • CO₂ accuracy up to ±(30 ppm + 2% of reading)
  • Temperature measurement from −5 to +55 °C
  • Optional HUMICAP® relative-humidity measurement from 0 to 95 %RH
  • Voltage, current or Modbus RTU output models
  • Display and CO₂ status-indicator options
  • Field-exchangeable calibrated measurement modules
  • Traceable three-point CO₂ calibration certificate included
Indigo200 Series Transmitters for Vaisala smart probes for Vaisala Smart Probes

Vaisala Indigo200 Series Transmitters

Vaisala Indigo200 Series Transmitters

The Vaisala Indigo200 Series is the standard transmitter platform for one interchangeable Indigo-compatible smart probe, providing local display and practical automation-system connectivity.

  • Indigo201 with three analog outputs and two relays
  • Indigo202 with Modbus RTU and two relays
  • Colour display with numerical and graphical views
  • IP65 enclosure for industrial measurement applications
Vaisala Indigo510 Indigo520 Malaysia

Vaisala Indigo510 and Indigo520 Flagship Transmitters

Vaisala Indigo510 and Indigo520 Flagship Transmitters

The Vaisala Indigo500 Series provides flagship industrial measurement integration: choose Indigo510 for a simplified single-probe system or Indigo520 for full dual-probe capability.

  • Indigo510: one probe and two isolated analog outputs
  • Indigo520: two probes, four isolated outputs and two relays
  • Ethernet web interface and Modbus TCP communication
  • Rugged IP66 and NEMA 4 metal enclosure
Incubator CO₂ Probe GMP231

Vaisala GMP231 CO₂ Probe for Incubators

Vaisala GMP231 CO₂ Probe for Incubators

The Vaisala GMP231 is an OEM carbon-dioxide probe designed for accurate measurement and permanent wall installation in life-science incubators.

  • CO₂ measurement range from 0 to 20%
  • Measurement performance optimized around 5% CO₂
  • Sensor head withstands heat sterilisation at +180 °C
  • At least 120 specified +180 °C sterilisation cycles
  • Internal temperature and pressure measurement for compensation
  • Heated sensor head helps prevent condensation
  • I²C, Vaisala RS-485 protocol and scalable 0–20 mA options
  • Four-point traceable CO₂ calibration certificate included
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