Intrinsically Safe Digital Thermometers for Hazardous Locations since 1983.
Designed and Made in the USA


Intrinsically Safe Portable Stem Thermometer for Laboratory and Field – Precision Reference


The Intrinsically Safe TL3-R is ThermoProbe’s highest accuracy hand-held reference Thermometer. The TL3-R has been certified to the latest global standards for hazardous locations (Ex).

 Available with Bluetooth connectivity, the TL3-R can be used in applications where extreme accuracy is required. It is powered with 2-AAA batteries providing excellent battery life. A large display and easy to hold design makes the TL3-R convenient for use as a reference in the lab or field. The rugged, weather resistant case and buttons are well suited for use in industrial applications, even with gloves. The TL3-R precision circuitry provides excellent temperature accuracy, battery life and Bluetooth monitoring.

Bluetooth Software & Documentation

Versatile software functions allow easy selection of Celsius or Fahrenheit units, Display resolution or Bluetooth activity. Minimum, maximum and average temperatures are automatically stored to memory for later reference. Low battery display, and failure mode indications protect the user from false data. Encoded Calibration is unaffected by temperature, vibration, or battery removal.

Through numerous distributors equipped for calibration and repair, the TL3-R can be supported in many locations throughout the world.

A one year warranty, protective case and NIST traceable 5 point calibration report are included.


The TL3-R is recognized with international (IECEx) and European (ATEX) safety certificates.

Distillations, temperature baths, melting point tests, flash point tests, reference, thermowells, provers, temperature calibration for flow meters. See ASTM D8164 Standard Guide for Digital Contact Thermometers for Petroleum Products, Liquid Fuels, and Lubricant Testing.

TL3 Model Comparison


Interface Features

0.5" (12.7mm) character LCD
Switchable units °C or °F
Resolution 0.01 or 0.001
Bluetooth Wireless Transmitter
Low Battery & Fault indication
Zero Correction Mode
Continuous operation or Auto Off after 20 minutes.
Stores and displays Average, Lowest & Highest readings.
Arrows indicating increasing/decreasing temperature.
Recommended ambient temperature range: 32°F to 112°F
(0°C to 44°C)


Weather Resistant Enclosure
Stainless steel RTD temperature sensor
Static-dissipative plastic housing with a durable
polyester graphics window.
Nominal body dimensions: 5 x 1.75 x 1.15"
(13 x 4.4 x 2.9cm)


5.5oz (156 grams)
– with 8" sensor


Resolution 0.001 Degrees
Calibrated Accuracy:
±0.05°F from -30 to 320°F
±0.03°C from -36 to 160°C
Range: -40°F to 400°F (-40°C to 204°C)
NIST Traceable Report of Test
Standard 5 point calibration: -4°F(-20°C), 32°F(0°C) , 120°F(49°C),
199°F(93°C) & 300°F(149°C)

Temperature Response Characteristics

Temperature time constant:
10 seconds in circulated water bath
(time response to 63.2% of temp. step change)


Stainless steel RTD temperature sensor
– 100Ω Precision wire wound platinum RTD
– Standard 8"(20cm) or 12"(30cm) lengths
– Standard 0.25"(6.35mm) diameter
– Recommended Minimum Immersion Depth: 4" (10.2cm)


2 AAA Duracell MN2400
Over 450 hours service life at 70°F (21°C)
Ambient temperature operating range -4°F to 130°F
(-20°C to 54°C)
Note: Battery may not provide adequate power if used
outside operating range.


Specifications subject to change, See data sheet for latest information.
Custom ranges, configurations and sensor lengths available upon request.