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The Vaisala CARBOCAP® Carbon Dioxide Probe GMP251 is an intelligent, stand-alone, %-level probe for measuring CO2 in life science incubators, cold storage facilities, fruit and vegetable transportation, and in all demanding applications where stable and accurate percentage-level CO2 measurements are needed. The operating temperature range is -40 … +60 °C and the measurement range is 0 … 20%CO2.
The GMP251 is based on Vaisala’s innovative ,second-generation CARBOCAP® technology that provides exceptional stability. A new type of infrared (IR) light source is used instead of the traditional incandescent light bulb, which extends the lifetime of the GMP251. It has full temperature and pressure compensations of CO2 measurement – integrated temperature measurement for compensation purposes. The sensor head is heated to avert condensation. Digital output over RS-485: Modbus & Vaisala Industrial Protocol.
The GMP251 probe is part of the Indigo product family and can also be connected to the Indigo 500 and Indigo 200 series transmitters to extend its features, for example, for a display or relays.
Measurement Performance
| Measurement range | 0 ... 20 %CO2 |
| Accuracy at 25 °C (77 °F) and 1013 hPa (incl. repeatability and non-linearity) | |
| At 5 %CO2 | ±0.1 %CO2 |
| 0 ... 8 %CO2 | ±0.2 %CO2 |
| 8 ... 20 %CO2 | ±0.4 %CO2 |
| Calibration uncertainty | |
| At 5 %CO2 | ±0.12 %CO2 |
| At 20 %CO2 | ±0.32 %CO2 |
| Long-term stability | |
| 0 ... 8 %CO2 | ±0.3 %CO2/year |
| 8 ... 12 %CO2 | ±0.5 %CO2/year |
| 12 ... 20 %CO2 | ±1.0 %CO2/year |
| Temperature dependence | |
| With compensation at 5 %CO2, 0 ... +50 °C (+32 ... +122 °F) | < ±0.05 %CO2 |
| With compensation, 0 … 20 %CO2,-40 … +60 °C (-40 ... +140 °F) | ±0.045 % of reading/°C |
| Without temperature compensation at 5 %CO2 (typical) | -0.25 % of reading/°C |
| Pressure dependence | |
| With compensation at 5 %CO2 700 ... 1100 hPa | ±0.05 %CO2 |
| With compensation, 0 … 20 %CO2 500 ... 1200 hPa | ±0.015 % of reading/hPa |
| Without compensation (typical) | +0.15 % of reading/hPa |
| Humidity dependence | |
| With compensation, 0 … 20 %CO2, 0 … 100 %RH | ±0.7 % of reading (at +25 °C (+77 °F)) |
| Without compensation (typical) | +0.05 % of reading / %RH |
| O2 dependence | |
| With compensation, 0 … 20 %CO2, 0 ... 90 %O2 | ±0.6 % of reading (at +25 °C (+77 °F)) |
| Without compensation (typical) | -0.08 % of reading / %O2 |
| Flow rate dependence (for flow-through option) | |
| < 1 l/min flow | No effect |
| 1 … 10 l/min flow | < 0.6 % of reading/ l/min |
| Start-up time at +25 °C (+77 °F) | < 10 s |
| Warm-up time for full spec. | < 4 min |
| Response time (T90) | |
| With standard filter | < 1 min |
| Flow-through model with > 0.1 l/min | < 1 min |
| With spray shield | < 2 min |
Operating environment
| Operating temperature of CO2 measurement | -40 ... +60 °C (-40 ... +140 °F) |
| Storage temperature | -40 ... +70 °C (-40 ... +158 °F) |
| Pressure | |
| Compensated | 500 ... 1100 hPa |
| Operating | < 1.5 bar |
| Humidity | 0 ... 100 %RH, non-condensing |
| Gas flow (for flow-through option) | |
| Operating range | < 10 l/min |
| Recommended range | 0.1 … 0.8 l/min |
| Condensation prevention | Sensor head heating, when power on |
| EMC compliance | EN61326-1, Generic Environment |
| Chemical tolerance (temporary exposure during cleaning) |
|
Mechanical specifications
| Weight, probe | 45 g (1.59 oz) |
| Materials | |
| Probe housing | PBT polymer |
| Filter | PTFE membrane, PBT polymer grid |
| Connector | Nickel plated brass, M12 / 5-pin |
| IP rating, probe body | IP65 |
| Connector | M12 5-pin male |
| Dimensions | |
| Probe diameter | 25 mm (0.98 in) |
| Probe length | 96 mm (3.78 in) |
Inputs and outputs
| Analog outputs |
|
| Digital output | Over RS-485:
|
| Operating voltage | |
| With digital output in use | 12 ... 30 VDC |
| With voltage output in use | 12 ... 30 VDC |
| With current output in use | 20 ... 30 VDC |
| Power consumption | |
| Typical (continuous operation) | 0.4 W |
| Maximum | 0.5 W |
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