FW1 Type E Fine-Wire Thermocouple
Research Grade
High accuracy for temperature-gradient and eddy-covariance applications
weather applications water applications energy applications gas flux & turbulence applications infrastructure applications soil applications


The FW1 is a Type E thermocouple with a 0.001 in. diameter. It measures atmospheric temperature gradients or fluctuations with research-grade accuracy. The FW1 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

The FW/ENC Carrying Case is required to ship our FW1 thermocouples. It holds up to four thermocouples.


Detailed Description

The FW1'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.

A reference temperature measurement is required for thermocouple measurements. The temperature sensor built into many of our dataloggers' wiring panel typically provides this measurement.


Type Chromel-Constantan
Typical Output 60 μV/°C
Accuracy Refer to the Thermocouple Measurement section in the datalogger manual.
Diameter 0.0254 mm (0.001 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)


Datalogger Considerations

The thermocouple connects to the datalogger via the FWC cable. One differential analog input per sensor is required.

Compatible Contemporary Dataloggers

CR200(X) Series CR800/CR850 CR1000 CR3000 CR9000X CR6 Series

Compatible Retired Dataloggers

CR500 CR510 CR10 CR10X 21X CR23X CR9000 CR5000 CR7X

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 FW1 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.

Frequently Asked Questions

Number of FAQs related to FW1: 2

  1. Most Campbell Scientific dataloggers can measure a thermocouple without any external signal conditioning. Therefore, a dedicated module is not required.

  2. No. The fine-wire thermocouples were designed to measure ambient air temperature.