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GMP252 catalogue
CO₂ Probe GMP252
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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
Percentage-Level CO₂ Measurement for Demanding Applications
The Vaisala GMP251 is designed for applications where carbon dioxide is measured in percentage rather than normal ambient-air ppm levels. Typical uses include life-science incubators, controlled-atmosphere storage, fruit and vegetable transportation, cold rooms, greenhouses and industrial chambers.
Its second-generation Vaisala CARBOCAP® sensor combines an internal reference with a durable infrared light source for stable long-term measurement. The probe can operate independently with analogue or Modbus RTU output, or connect to a Vaisala Indigo transmitter for a local display, relays and additional system interfaces.
Range selection: Choose GMP251 for percentage-level CO₂ up to 20%. For ppm-level applications such as demanding HVAC, refrigeration or plant-growth equipment, use the Vaisala GMP252.
GMP251 Measurement Performance
| Specification | GMP251 |
|---|---|
| Measurement range | 0 to 20% CO₂ |
| Accuracy at 5% CO₂ | ±0.1% CO₂ |
| Accuracy from 0 to 8% CO₂ | ±0.2% CO₂ |
| Accuracy from 8 to 20% CO₂ | ±0.4% CO₂ |
| Typical calibration uncertainty at 5% CO₂ | ±0.07% CO₂ |
| Typical calibration uncertainty at 20% CO₂ | ±0.27% CO₂ |
| Start-up time at +25 °C | Less than 10 seconds |
| Warm-up time for full specification | Less than four minutes |
| Response time with standard filter | Less than one minute, T90 |
| Sensor technology | Vaisala CARBOCAP® non-dispersive infrared sensor |
The accuracy values apply at +25 °C and 1013 hPa and include repeatability and non-linearity. Configure the environmental compensations correctly when temperature, pressure, humidity or oxygen concentration differs from the reference conditions.
Why Environmental Compensation Matters
| Influence | GMP251 capability | Application guidance |
|---|---|---|
| Temperature | Integrated temperature measurement or a configured fixed value | Use the integrated compensation when chamber temperature changes during normal operation |
| Pressure | Configurable compensation from 500 to 1100 hPa | Enter the actual process pressure when accurate percentage-level measurement is required |
| Humidity | Water-vapour compensation over 0 to 100 %RH | Humidity affects gas composition and should be included when conditions vary |
| Oxygen | Configurable background-gas compensation from 0 to 90% O₂ | Particularly important in modified-atmosphere or unusual gas mixtures |
A probe can be correctly calibrated yet still show an unsuitable process value if its pressure or background-gas compensation is wrong. Record the compensation settings as part of commissioning and validation documentation.
Inputs, Outputs and Mechanical Specifications
| Specification | GMP251 |
|---|---|
| Voltage output | Scalable 0–5 V or 0–10 V; minimum load 10 kΩ |
| Current output | Scalable 0–20 mA or 4–20 mA; maximum load 500 Ω |
| Digital output | RS-485 with Modbus RTU or Vaisala Industrial Protocol |
| Supply with digital or voltage output | 12 to 30 V DC |
| Supply with current output | 20 to 30 V DC |
| Power consumption | 0.4 W typical; 0.5 W maximum |
| Operating temperature | −40 to +60 °C |
| Operating humidity | 0 to 100 %RH, non-condensing |
| Operating pressure | Below 1.5 bar |
| Probe-body protection | IP65 |
| Probe dimensions | 25 mm diameter and 96 mm length |
| Weight | Approximately 42 g |
| Electrical connector | M12 5-pin male |
Typical GMP251 Applications
| Application | Why GMP251 fits | Installation consideration |
|---|---|---|
| Life-science incubators | Accurate measurement around common percentage-level CO₂ setpoints | Review sterilisation temperature and probe exposure; GMP231 may suit direct incubator integration |
| Controlled-atmosphere storage | Measures elevated CO₂ used to manage stored produce | Configure oxygen, humidity and pressure compensation for the gas mixture |
| Cold storage and transport | Wide operating-temperature range and IP65 probe body | Prevent liquid condensation and protect the cable connection |
| Greenhouses and cultivation | Stable monitoring where CO₂ enrichment reaches percentage levels | Confirm whether the actual range is percentage or ppm before selecting GMP251 |
| Environmental chambers | Compact standalone probe with analogue and digital connectivity | Choose a mounting flange, clip, probe holder or flow-through arrangement |
| OEM equipment | M12 connection and configurable outputs support equipment integration | Design for service access, environmental compensation and future calibration |
Vaisala GMP251 or GMP252?
| Selection point | GMP251 | GMP252 |
|---|---|---|
| Primary range | 0 to 20% CO₂ | 0 to 10,000 ppm CO₂ |
| Extended measurement | Percentage-level measurement up to 20% | Can measure up to 30,000 ppm with reduced accuracy |
| Best suited to | Incubators, controlled atmospheres, cold storage and percentage-level processes | Demanding HVAC, refrigeration, agriculture and ppm-level process measurement |
| Typical accuracy point | ±0.1% CO₂ at 5% CO₂ | ±40 ppm from 0 to 3000 ppm |
| Environmental compensation | Temperature, pressure, humidity and oxygen | Temperature, pressure, humidity and oxygen |
| Standalone outputs | Voltage, current or RS-485 | Voltage, current or RS-485 |
| Indigo compatibility | Indigo200, Indigo300, Indigo500 and Indigo80 | Indigo200, Indigo300, Indigo500 and Indigo80 |
| Choose this model when | The expected concentration is normally above the ppm-level range | The expected concentration is expressed in ppm and remains below the probe's useful range |
| Product information | GMP251 is detailed on this page | Explore Vaisala GMP252 |
Use GMP251 Standalone or with an Indigo Transmitter
| Configuration | Connection and outputs | Recommended when |
|---|---|---|
| GMP251 standalone | Direct analogue or Modbus RTU connection | No local display, relay or additional transmitter enclosure is required |
| Indigo200 Series | One probe with display, analogue or Modbus RTU model and two relays | A standard industrial transmitter and local interface are required |
| Indigo300 | One probe, IP66 metal enclosure and three analogue outputs | A rugged analogue-focused installation is preferred |
| Indigo510 | One probe, two isolated analogue outputs, Ethernet and Modbus TCP | A premium single-probe system with web access is required |
| Indigo520 | Two probes, four isolated analogue outputs, two relays, Ethernet and Modbus TCP | GMP251 must be combined with another compatible probe or additional control functions |
| Product information | Explore Vaisala Indigo200 Explore Vaisala Indigo300 Explore Vaisala Indigo510 and Indigo520 | |
Portable Measurement with Indigo80 and GMP80P
GMP251 can connect to the Vaisala Indigo80 for portable display, configuration, logging, diagnostics and calibration. For pump-aspirated sampling through an incubator port or sample tube, the GMP80P combines the GMP251 measurement probe with a portable pump arrangement.
Explore Vaisala Indigo80 and GMP80P
Calibration and Maintenance
GMP251 supports one-point or two-point CO₂ adjustment. Calibration and configuration can be performed through Vaisala Insight PC software, a compatible Indigo transmitter, Indigo80 or supported MI70 equipment. The optional DRW244827SP adapter allows reference gas to be applied to the probe during calibration.
- Use certified reference gases that cover the application range and required uncertainty.
- Enter the correct environmental compensation values during calibration.
- Allow the measurement to stabilise before recording or adjusting each point.
- Inspect and replace the filter when contamination or damage affects response.
- Set the calibration interval according to process criticality, exposure and quality requirements.
- Record the reference-gas certificates, as-found result, adjustment and as-left result.
Vaisala GMP251 Supplier and Technical Support in Malaysia
Seacom Process Instruments supplies and supports the Vaisala GMP251 Percentage-Level CO₂ Probe in Malaysia for incubators, life-science equipment, controlled-atmosphere storage, cold-chain applications, environmental chambers and demanding industrial processes.
Our team can help confirm whether GMP251 or GMP252 is appropriate, select the standalone output or Indigo transmitter, specify cables and mounting accessories, and review temperature, pressure, humidity and oxygen compensation. We can also assist with Indigo80/GMP80P portable sampling, commissioning and calibration planning.
Selecting a GMP251 configuration? Send us the normal and maximum CO₂ concentration, temperature, pressure, humidity, oxygen level, installation method, output signal, controller interface and calibration requirement.
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- At least 120 specified +180 °C sterilisation cycles
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- Heated sensor head helps prevent condensation
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