High accuracy for temperature-gradient and eddy-covariance applications
Overview
The FW3 is a Type E thermocouple with a 0.003 in. diameter. It measures atmospheric temperature gradients or fluctuations with research-grade accuracy. The FW3 is compatible with most Campbell Scientific dataloggers, and it is often used in eddy-covariance systems.
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Benefits and Features
- High frequency response suitable for eddy-covariance applications
- Extremely small diameter virtually eliminates solar loading
- Well-suited for temperature gradient measurements
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Detailed Description
The FW3's small mass eliminates the need for a solar radiation shield. It consists of a type E thermocouple with a connector. The connector attaches the thermocouple to a datalogger via the FWC-L cable.
Type E thermocouples are comprised of a chromel wire and a constantan wire joined at a measurement junction. A voltage potential is generated when the measurement end of the thermocouple is at a different temperature than the reference end of the thermocouple. The magnitude of the voltage potential is related to the temperature difference. Therefore, temperature can be determined by measuring the differences in potential created at the junction of the two wires.
Specifications
| Type | Chromel-Constantan |
| Typical Output | 60 μV/°C |
| Accuracy | Refer to the Thermocouple Measurement section in the data logger manual. |
| Diameter | 0.0762 mm (0.003 in.) |
| Length | 36.8 cm (14.5 in.) |
| Plug Dimensions | 1.8 x 3.3 x 1.0 cm (0.7 x 1.3 x 0.4 in.) |
| Weight | 45 g (2 oz) |
Compatibility
Please note: The following shows notable compatibility information. It is not a comprehensive list of all compatible products.
Dataloggers
| Product | Compatible | Note |
|---|---|---|
| CR1000 (retired) | ||
| CR1000X | The CR1000X is compatible when used with the CDM-A108 or CDM-A116. | |
| CR3000 (retired) | ||
| CR6 | The CR6 is compatible when used with the CDM-A108 or CDM-A116. | |
| CR800 (retired) | ||
| CR800 (retired) | ||
| CR850 (retired) | ||
| CR850 (retired) |
Additional Compatibility Information
Data Logger Considerations
The thermocouple connects to the data logger via the FWC cable. One differential analog input per sensor is required.
Reference Temperature Measurement
A reference temperature measurement is required. Options for measuring the reference temperature include:
- Thermistor built into the CR800, CR850, CR1000, CR3000, or CR5000 wiring panel
- PRT built into the wiring panel of the CR9050 or
- CR9051E input module for the CR9000X Measurement and Control Datalogger
- PRT built into the wiring panel of the CR723T input card for the CR7 Measurement and Control Datalogger
- CR10XTCR thermistor that connects to the CR10X wiring panel
Carrying Case
The FW/ENC Carrying Case is required to ship our FW3 thermocouples. It holds up to four thermocouples. Thermocouples returned to Campbell Scientific for repair without this case will be shipped to the customer in a new case and the account charged accordingly.
Documents
Frequently Asked Questions
Number of FAQs related to FW3: 3
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No. The fine-wire thermocouples were designed to measure ambient air temperature.
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Most Campbell Scientific data loggers can measure a thermocouple without any external signal conditioning. Therefore, a dedicated module is not required.
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No. If the fan is off during the day, the shield will suffer from radiation loading, and the thermocouple will measure a higher ambient air temperature. If the fan is off during the night, under clear sky conditions, the ASPTC-L shield will emit long-wave radiation and cool to a temperature lower than ambient air temperature. Consequently, the thermocouple will measure a lower ambient air temperature. Running the fan and aspirating the thermocouple ensures that it is measuring ambient air temperature.
If the site temperature is expected to fall below -10°C, consider using a naturally aspirated fine-wire thermocouple, such as the FW3, FW1, or FW05, in combination with the FWTM Fine-Wire-Thermocouple Mount and the FWC-L Connector Cable for Fine Wire Thermocouples.
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