Can be used in a variety of applications
Overview
The 108 is a rugged, accurate probe that measures temperature of air, soil, or water from -5° to +95°C. It easily interfaces with most Campbell Scientific dataloggers and can be used in a variety of applications.
The 108 consists of a thermistor encapsulated in an epoxy-filled aluminum housing. The housing protects the thermistor. allowing you to bury the probe in soil or submerge it in water.
Benefits and Features
- Versatile product—measures air, soil, or water temperature
- Easy to install or remove
- Durable
- Compatible with AM16/32-series multiplexers allowing measurement of multiple sensors
Images
Specifications
| Sensor Description | BetaTherm 100K6A1IA Thermistor |
| Tolerance | ±0.2°C (over 0° to 70°C range) |
| Temperature Measurement Range | -5° to +95°C |
| Steinhart-Hart Equation Error | ≤ ±0.01°C over measurement range (CRBasic data loggers only) |
| Polynomial Linearization Error | Typically < ±0.5°C over -5° to 90°C range (Edlog data loggers only) |
| Time Constant in Air | 30 to 60 s (in a wind speed of 5 m s-1) |
| Maximum Submergence | 15 m (50 ft) |
| Maximum Cable Length | 305 m (1000 ft) |
| Probe Diameter | 0.76 cm (0.3 in.) |
| Probe Length | 10.4 cm (4.1 in.) |
| Weight | 136 g (5 oz) with 3.05 m (10 ft) cable |
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) | ||
| CR300 | ||
| CR3000 (retired) | ||
| CR310 | ||
| CR350 | ||
| CR6 | ||
| CR800 (retired) | ||
| CR800 (retired) | ||
| CR850 (retired) | ||
| CR850 (retired) | ||
| CR850 (retired) | ||
| CR850 (retired) |
Additional Compatibility Information
Data Logger Considerations
One single-ended channel per probe is required; an excitation channel can be shared by several probes.
Installation Considerations
Air Temperature
When exposed to sunlight, the 108 should be housed in a 41303-5A, 41303-5B, or RAD06 6-plate radiation shield. The louvered construction of these radiation shields allows air to pass freely through the shield, thereby keeping the sensor at or near ambient temperature. The shields’ white color reflects solar radiation.
The RAD06 uses a double-louvered design that offers improved sensor protection from driving rain, snow, insect intrusion and has lower self-heating in bright sunlight combined with higher temperatures (> 24°C [~75°F]) and low wind speeds (< 2 m/s [~4.5 mph]), giving a better measurement.
The 41303-5A and RAD06 attach to a crossarm, mast, or user-supplied pipe with a 2.5 to 5.3 cm (1.0 in to 2.1 in.) outer diameter. The 41303-5B attaches to a CM500-series pole or a user-supplied pole with a 5.1 cm (2.4 in.) outer diameter.
Soil Temperature
The 108 is suitable for shallow burial only. Placement of the sensor’s cable inside a rugged conduit may be advisable for long cable runs—especially in locations subject to digging, mowing, traffic, use of power tools, or lightning strikes.
Water Temperature
The sensor can be submerged to 15 m (50 ft) or 21 psi. Please note that the 108 is not weighted. Therefore, the installer should either add a weighting system or secure the sensor to a fixed, submerged object, such as a piling.
Multiplexers
To measure large numbers of probes, the AM16/32B multiplexer is recommended.
Related Documents
Product Brochures
Manuals
Related FAQs
Number of FAQs related to 108-L: 5
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The thermistor is located approximately 3 mm (0.125 in.) back from the probe tip.
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Note the difference between calibration and a field check. Calibration cannot be done in the field, as it requires an experienced technician and specialized equipment.
Field checks of measurements can be done to determine if the data make sense with the real-world conditions. Follow these steps to field check a sensor:
- Find a second sensor of the same type as the installed sensor whose data is in question. The second sensor will be used as a benchmark sensor and should be known to be accurate or recently calibrated.
- At the site, take readings using both sensors under the same conditions. The best practice is to measure both sensors side-by-side at the same time. Note that the sensors will never have the exact same measurement.
- Depending on the sensor model, if the difference in the readings of the installed and benchmark sensors is greater than the sum of the accuracies for both sensors, either return the installed sensor to Campbell Scientific for calibration or replace the appropriate chip.
- The 107-L/LC, 108-L/LC, 109-L, 110PV-L, and BlackGlobe-L temperature sensors can be calibrated.
- The HC2S3-L and HMP155A-L temperature and relative humidity sensors can be calibrated.
- The CS215-L has a replaceable chip for temperature and relative humidity. For more information, refer to the “Maintenance and Calibration” section of the CS215 instruction manual.
- The HMP60-L has a replaceable chip for relative humidity only. For more information, refer to the “Maintenance” section of the HMP60 instruction manual.
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Most Campbell Scientific sensors are available as an –L, which indicates a user-specified cable length. If a sensor is listed as an –LX model (where “X” is some other character), that sensor’s cable has a user-specified length, but it terminates with a specific connector for a unique system:
- An –LC model has a user-specified cable length for connection to an ET107, CS110, or retired Metdata1.
- An –LQ model has a user-specified cable length for connection to a RAWS-P weather station.
If a sensor does not have an –L or other –LX designation after the main model number, the sensor has a set cable length. The cable length is listed at the end of the Description field on the product’s Ordering tab. For example, the 034B-ET model has a description of “Met One Wind Set for ET Station, 67 inch Cable.” Products with a set cable length terminate, as a default, with pigtails.
If a cable terminates with a special connector for a unique system, the end of the model number designates which system. For example, the 034B-ET model designates the sensor as a 034B for an ET107 system.
- –ET models terminate with the connector for an ET107 weather station.
- –ETM models terminate with the connector for an ET107 weather station, but they also include a special system mounting, which is often convenient when purchasing a replacement part.
- –QD models terminate with the connector for a RAWS-F Quick Deployment Station.
- –PW models terminate with the connector for a PWENC or pre-wired system.
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The sensor/probe consists of a non-linear thermistor configured with a precision resistor in a half-bridge circuit, as shown in the product’s manual:
- Model 107 Temperature Probe Instruction Manual
- Model 108 Temperature Probe Instruction Manual
- 108-LC Temperature Probe for MetData1 Instruction Manual
- Model 109 Temperature Probe Instruction Manual
To measure the sensor/probe, the measurement device has to provide a precision excitation voltage (Campbell Scientific dataloggers use 2000 mV), measure the voltage across the precision resistor, determine the thermistor resistance (Ohm's law), and convert the resistance to temperature using the Steinhart-Hart equation.
The Steinhart-Hart equation is 1/T = A + Bln(R) + C(ln(R))3 where:
- T is the temperature in Kelvin
- R is the resistance at T in ohms
- A, B, and C are the Steinhart-Hart coefficients, which vary depending on the temperature range of interest, as well as the type and model of the thermistor
For the 107-L, 107-LC, 108-L, and 108-LC, the following are the coefficients for the Steinhart-Hart equation:
- A = 8.271111E-4
- B = 2.088020E-4
- C = 8.059200E-8
For the 109-L, the following are the coefficients for the Steinhart-Hart equation:
- A = 1.129241E-3
- B = 2.341077E-4
- C = 8.775468E-8
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Many Campbell Scientific sensors are available with different cable termination options. These options include the following:
- The –PT (–PT w/Tinned Wires) option is the default option and does not display on the product line as the other options do. The cable terminates in pigtails that connect directly to a datalogger.
- In the –C (–C w/ET/CS110 Connector) option, the cable terminates in a connector that attaches to a CS110 Electric Field Meter or an ET-series weather station.
- In the –CWS (–CWS w/CWS900 Connector) option, the cable terminates in a connector that attaches to a CWS900-series interface. Connection to a CWS900-series interface allows the sensor to be used in a wireless sensor network.
- In the –PW (–PW w/Pre-Wire Connector) option, the cable terminates in a connector that attaches to a prewired enclosure.
- In the –RQ (–RQ w/RAWS Connector) option, the cable terminates in a connector that attaches to a RAWS-P Permanent Remote Automated Weather Station.
Note: The availability of cable termination options varies by sensor. For example, sensors may have none, two, or several options to choose from. If a desired option is not listed for a specific sensor, contact an application engineer at Campbell Scientific for assistance.
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