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


Intrinsically Safe Portable Stem Thermometer for Laboratory and Field Reference


The Intrinsically Safe TL3-A thermometer is the latest evolution of ThermoProbe’s industry standard TL series. The TL3-A has been certified to the latest global standards for hazardous locations (Ex).

A large display and easy to hold design makes the TL3-A more convenient for use as a reference in the lab or field. The rugged plastic alloy case and buttons are well suited for use in industrial applications, even with gloves. The TL3-A innovative circuitry provides improved temperature accuracy, response time and battery life.

TL3-A thermometers are intended to be used anywhere a precision glass stem thermometer or other type thermometer is used. Versatile software functions allow easy selection of Celsius or Fahrenheit units and display resolution. 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-A can be supported in many locations throughout the world.

A one year warranty, protective case and NIST traceable 4 point calibration report are included


The TL3-A 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 0.1 or 0.01
Low Battery & Fault indication
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)


Static-dissipative plastic enclosure with a durable
polyester graphics window.
Stainless Steel RTD temperature sensor
Nominal body dimensions: 5 x 1.75 x 0.85"
(13 x 4.4 x 2.2cm)


4oz (113 grams)
– with 8" sensor


Resolution 0.01 Degrees
Calibrated Accuracy:
±0.1°F from 14 to 320°F
±0.06°C from -10 to 160°C
Range: -40°F to 400°F (-40°C to 204°C)
NIST Traceable Report of Test
Standard 4 point calibration: 32°F(0°C) , 120°F(49°C),
199°F(93°C) & 300°F(149°C)

Temperature Response Characteristics

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


Stainless Steel RTD temperature sensor
– 100Ω Shock resistant Thin Film RTD
– Standard 8"(20cm) or 12"(30cm) lengths
– Standard 0.25"(6.35mm) diameter with 0.188" (4.76mm) reduced tip
– Recommended Minimum Immersion Depth: 3" (7.6cm)


3V Duracell DL2032 coincell
Over 150 hours service life at 70°F (21°C)
Ambient temperature operating range -4°F to 140°F
(-20°C to 60°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.