The Vaisala GMP252 is an intelligent standalone probe for stable ppm-level carbon-dioxide measurement in demanding HVAC, refrigeration, agriculture and industrial applications.
The Vaisala GMP252 is designed for applications that require accurate carbon-dioxide measurement above normal ambient conditions while remaining within a ppm-level range. Typical applications include demanding HVAC, refrigeration equipment, greenhouses, plant-growth chambers, cold storage, controlled environments and OEM equipment.
Its second-generation Vaisala CARBOCAP® sensor uses an internal reference and Microglow infrared light source for stable long-term operation. The compact probe can work independently with analogue or Modbus RTU output or connect to a Vaisala Indigo transmitter for a display, relays and additional system interfaces.
Range selection: GMP252 is the ppm-level model. Choose the Vaisala GMP251 when the process normally operates at percentage-level CO₂ concentrations up to 20%.
| Specification | GMP252 |
|---|---|
| Measurement range | 0 to 10,000 ppm CO₂ |
| Extended measurement | Up to 30,000 ppm with reduced accuracy |
| Accuracy from 0 to 3000 ppm | ±40 ppm CO₂ |
| Accuracy from 3000 to 10,000 ppm | ±2% of reading |
| Accuracy up to 30,000 ppm | ±3.5% of reading |
| Typical calibration uncertainty at 2000 ppm | ±31 ppm CO₂ |
| Typical calibration uncertainty at 10,000 ppm | ±105 ppm CO₂ |
| Start-up time at +25 °C | Less than 12 seconds |
| Warm-up time for full specification | Less than two minutes |
| Response with standard filter | Less than one minute, T90 |
| Response in flow-through use above 0.1 l/min | Approximately 30 seconds, T90 |
The stated accuracy applies at +25 °C and 1013 hPa and includes repeatability and non-linearity. Configure the environmental compensations correctly when temperature, pressure, humidity or oxygen differs from the reference conditions.
| Influence | GMP252 capability | Application guidance |
|---|---|---|
| Temperature | Integrated temperature measurement or configured fixed value | Use active compensation where equipment temperature changes during operation |
| Pressure | Configurable compensation from 500 to 1100 hPa | Enter actual pressure when measurement accuracy matters or atmospheric pressure varies |
| Humidity | Water-vapour compensation from 0 to 100 %RH | Configure humidity for wet processes, refrigeration and greenhouse use |
| Oxygen | Configurable background-gas compensation from 0 to 90% O₂ | Use the actual oxygen concentration for unusual gas mixtures |
Incorrect environmental settings can create measurement error even when the probe itself is correctly calibrated. Record the compensation values during commissioning and review them whenever process conditions change.
| Specification | GMP252 |
|---|---|
| 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 |
| Recommended flow-through rate | 0.1 to 0.8 l/min |
| Probe-body protection | IP65 |
| Probe dimensions | 25 mm diameter and 130 mm length |
| Weight | Approximately 55 g |
| Electrical connector | M12 5-pin male |
| Application | Why GMP252 fits | Installation consideration |
|---|---|---|
| Demanding HVAC | Accurate ppm-level measurement with wide temperature capability | For a complete duct enclosure, also consider the dedicated GMD110 transmitter |
| Refrigeration equipment | Heated sensor head and compensation support changing conditions | Avoid liquid condensation and protect the cable connection |
| Greenhouses and agriculture | Measures CO₂ enrichment above ambient concentrations | Use a representative location away from direct dosing jets |
| Plant-growth chambers | Compact probe with analogue and digital outputs for equipment integration | Configure temperature, pressure and humidity compensation |
| Cold storage | Wide −40 to +60 °C operating range | Check whether the maximum CO₂ remains within the ppm-level range |
| Outdoor CO₂ measurement | Can be installed with a suitable Vaisala DTR250 radiation shield | Use proper weather protection and a representative ventilated location |
| OEM equipment | M12 connection and configurable standalone outputs | Provide service access and document the output and compensation settings |
| Selection point | GMP252 | GMP251 |
|---|---|---|
| Primary range | 0 to 10,000 ppm CO₂ | 0 to 20% CO₂ |
| Extended measurement | Up to 30,000 ppm with reduced accuracy | Percentage-level measurement up to 20% |
| Best suited to | Demanding HVAC, refrigeration, agriculture and ppm-level equipment | Incubators, controlled atmospheres, cold storage and percentage-level processes |
| Typical accuracy point | ±40 ppm from 0 to 3000 ppm | ±0.1% CO₂ at 5% CO₂ |
| 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 process value is expressed in ppm and normally remains within the useful GMP252 range | The normal concentration is percentage-level or exceeds the practical GMP252 range |
| Product information | GMP252 is detailed on this page | Explore Vaisala GMP251 |
| Configuration | Connection and outputs | Recommended when |
|---|---|---|
| GMP252 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 | GMP252 must be combined with another compatible probe or additional control functions |
| Product information | Explore Vaisala Indigo200 Explore Vaisala Indigo300 Explore Vaisala Indigo510 and Indigo520 | |
GMP252 can connect to the Vaisala Indigo80 for portable display, configuration, data logging, diagnostics and calibration. This is useful when checking an installed process, comparing two compatible probes or carrying out adjustment work in the field.
Explore Vaisala Indigo80 Portable Meter
| Product | Installation | Choose it when |
|---|---|---|
| GMP252 | Machine, chamber, process, outdoor shield or custom mounting | A compact standalone ppm-level probe and flexible integration are required |
| GMD110 | Ventilation duct | A complete IP65 duct transmitter with terminal wiring is preferred |
| GMW80 Series | Occupied-room wall | A cost-effective room transmitter with HVAC output options is required |
| GMW90 Series | Occupied-room wall | Higher-performance room CO₂, temperature and optional humidity measurement is required |
| Product information | Explore Vaisala GMD110 Explore Vaisala GMW80 Explore Vaisala GMW90 | |
GMP252 can be configured, diagnosed and adjusted using Vaisala Insight PC software, a compatible Indigo transmitter, Indigo80 or supported MI70 equipment. Calibration frequency should reflect process criticality, environmental exposure, quality requirements and the required measurement uncertainty.
Seacom Process Instruments supplies and supports the Vaisala GMP252 PPM-Level CO₂ Probe in Malaysia for demanding HVAC, refrigeration, greenhouses, plant-growth chambers, cold storage, outdoor measurement and industrial equipment.
Our team can help confirm whether GMP252 or GMP251 is appropriate, select the standalone output or Indigo transmitter, specify cables and installation accessories, and review temperature, pressure, humidity and oxygen compensation. We can also assist with Indigo80 use, commissioning and calibration planning.
Selecting a GMP252 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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