109SS-L Stainless-Steel Temperature Probe for Harsh Environments
Rugged, Accurate, Versatile
Can be used in a variety of applications
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The 109SS is a rugged, accurate probe that measures soil or water temperature from -40° to +70°C. It is especially suited for harsh, corrosive environments, and can be easily interfaced with our dataloggers.

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Benefits and Features

  • Designed for harsh, corrosive environments
  • Fast response time
  • Wide temperature measurement range
  • Easy to install or remove
  • Compatible with most of our current and retired data loggers


Detailed Description

The 109SS consists of a thermistor encased in a sheath made from grade 316 stainless steel. The rugged stainless-steel sheath protects the thermistor allowing the 109SS to be buried or submerged in harsh, corrosive environments. This probe also has a fast time response.

The 109SS's thermistor can survive temperatures up to 100°C, but the overmolded joint and cable should not be exposed to temperatures hotter than +70°C.


Output Analog
Operating Temperature Range -40° to +70°C
  • Note: Overall probe accuracy is a combination of thermistor interchangeability, bridge-resistor accuracy, and error of the Steinhart-Hart equation. Interchangeability is the principle component error. If needed, an estimate of the interchangeability error for 0 to 50°C, that can be used as the Offset parameter of the Therm109() instruction, can be determined with a 1-point or 2-point calibration.
  • ±0.60°C (-40 to +70°C)
  • ±0.49°C (-20 to +70°C)
Maximum Submergence 45.7 m (150 ft) or 434 kPa (63 psi)
Temperature Measurement Range -40° to +70°C
Thermistor Temperature Survival Range -50° to +100°C
Overmolded Joint and Cable Temperature Survival Range -50° to +70°C
Interchangeability Error
  • ±0.6°C tolerance (-40°C)
  • ±0.38°C tolerance (0°C)
  • ±0.1°C tolerance (25°C)
  • ±0.3°C tolerance (50°C)
  • ±0.4°C tolerance (70°C)
Steinhart-Hart Equation Error ≤ 0.02°C (-40°)
Time Constant in Air
  • 31 s (still air)
  • 7.5 s (air @ 3 m/s)
  • 0.5 s (antifreeze/water rolling)
Sensor Description Micro-BetaCHIP Probe 10K3MCD1, 0.5 mm (0.018 in.) diameter, 10 kohm at 25°C
Cable Description 0.56 cm (0.22 in.) diameter with Santoprene jacket
Cable/Probe Connection “ATUM” heat shrink, “Macromelt” overmolded joint
Stainless-Steel Sheath Diameter 0.16 cm (0.063 in.)
Stainless-Steel Sheath Length 5.84 cm (2.3 in.)
Overmolded Joint Diameter 1.02 cm (0.40 in.)
Overmolded Joint Length 4.24 cm (1.67 in.)
Weight 0.1 kg with 3.2 m cable (0.2 lb with 10.5 ft cable)


Please note: The following shows notable compatibility information. It is not a comprehensive list of all compatible products.


Product Compatible Note
21X (retired)
CR10 (retired)
CR10 (retired)
CR1000 (retired)
CR10X (retired)
CR200X (retired)
CR206X (retired)
CR211X (retired)
CR216X (retired)
CR23X (retired)
CR3000 (retired)
CR500 (retired)
CR5000 (retired)
CR510 (retired)
CR9000 (retired)
CR9000X (retired)

Additional Compatibility Information

Data Logger Considerations


The instruction set for our CR200(X)-series, CR800-series, CR1000, and CR3000 dataloggers contains the Therm109 instruction for measuring the 109SS probe. Programming is more complicated for other data loggers because they must use generic measurement instructions.

Installation Considerations

Soil Temperature

The 109SS 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 46 m (150 ft) or 63 psi. Please note that the 109SS 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.