The Fluke Calibration 1551A-Ex is an intrinsically safe digital reference thermometer designed for accurate temperature measurements in calibration laboratories, industrial processes and hazardous environments.

With a temperature measurement range from −50 °C to +160 °C, accuracy of ±0.05 °C over its full range and a resolution of 0.01 °C, the Fluke Calibration 1551A-Ex combines excellent metrological performance with the convenience of a compact, self-contained thermometer.

Unlike a conventional thermometer readout that requires a separate external temperature probe, the 1551A-Ex combines the temperature sensor and digital readout in one portable instrument. This makes it particularly convenient for reference measurements, field calibration, verification of process temperature instruments and monitoring of calibration baths and dry block calibrators.

The instrument is part of the Fluke Calibration Stik Thermometer family and is designed as an alternative to traditional mercury-in-glass thermometers. Its intrinsically safe design allows it to be used in suitable potentially explosive environments.

A stainless steel probe, large backlit LCD, data logging capability and battery operation make the Fluke Calibration 1551A-Ex suitable for both laboratory and field use.

europascal provides professional temperature calibration equipment and calibration services for demanding industrial and laboratory applications.

For professional calibration and metrological traceability, visit the europascal Calibration Service.

Your Benefits at a Glance

• Temperature measurement range from −50 °C to +160 °C
• Accuracy of ±0.05 °C over the full range
• Temperature resolution of 0.01 °C
• Intrinsically safe design for hazardous environments
• ATEX and IECEx approvals
• Complete thermometer with integrated sensor and display
• 4.8 mm diameter stainless steel probe
• 200 mm probe length
• Minimum immersion depth of approximately 7 cm
• Fast response time
• Large backlit LCD
• Display in °C or °F
• Minimum, maximum and trend indication
• Integrated data logging
• Stores up to 10,000 time-stamped measurements
• Adjustable logging interval
• Battery-powered operation
• Long battery life of approximately 300 hours
• USB interface via optional connection cable
• Suitable for field and laboratory applications
• NIST traceable calibration supplied by Fluke Calibration
• Professional calibration support from europascal

Ideal for Demanding Temperature Measurements

The Fluke Calibration 1551A-Ex is designed for applications where a conventional industrial thermometer does not provide sufficient accuracy.

Its specified accuracy of ±0.05 °C across the complete temperature range makes the instrument suitable for use as a portable temperature reference.

Typical applications include checking temperature transmitters, sensors, indicators, process instrumentation, calibration baths and dry block calibrators.

The compact design eliminates the need to transport a separate reference probe and thermometer readout.

This is especially useful for technicians performing calibration and maintenance directly in industrial plants.

Temperature Range from −50 °C to +160 °C

The Fluke Calibration 1551A-Ex provides a temperature measurement range of:

−50 °C to +160 °C

This range covers numerous laboratory and industrial applications.

The 1551A-Ex is particularly suitable for measurements around ambient temperature as well as refrigeration and moderate high-temperature applications.

For applications requiring a higher maximum temperature, the related Fluke Calibration 1552A-Ex should be considered.

The temperature range describes the calibrated measuring capability of the thermometer and its integrated probe.

Accuracy of ±0.05 °C

One of the most important characteristics of the Fluke Calibration 1551A-Ex is its specified accuracy.

Fluke Calibration specifies:

±0.05 °C over the full temperature range

This performance allows the thermometer to be used for demanding reference measurements and comparison calibrations.

The specification should not be confused with calibration uncertainty.

The uncertainty stated on an individual calibration certificate must be considered separately when the thermometer is used as a reference standard.

Regular calibration is recommended to confirm the metrological performance of the instrument over time.

Temperature Resolution of 0.01 °C

The Fluke Calibration 1551A-Ex displays temperature with a resolution of:

0.01 °C

The fine resolution makes small temperature changes easy to identify.

This is useful when monitoring the stability of calibration baths, dry block calibrators or industrial processes.

The instrument can display temperature in degrees Celsius or degrees Fahrenheit.

Intrinsically Safe for Hazardous Areas

An important advantage of the Fluke Calibration 1551A-Ex is its intrinsically safe design.

The thermometer is intended for temperature measurements in suitable hazardous environments where conventional electronic instruments may not be permitted.

The 1551A-Ex carries international approvals including ATEX and IECEx certification.

This makes the thermometer particularly useful in industries such as:

• Chemical processing
• Petrochemical plants
• Oil and gas
• Pharmaceutical manufacturing
• Process industries
• Industrial maintenance

The applicable hazardous-area classification and all safety requirements must always be checked before using the instrument in an explosive atmosphere.

Integrated Reference Probe

The Fluke Calibration 1551A-Ex combines its digital readout and temperature sensor in one instrument.

The stainless steel probe has a diameter of approximately:

4.8 mm

and a length of:

200 mm

This compact probe design allows the thermometer to be inserted into calibration baths, dry blocks, thermowells and suitable industrial processes.

For accurate measurements, sufficient immersion is essential.

Fluke specifies a minimum immersion depth of approximately:

7 cm

Insufficient immersion can cause stem conduction errors and result in a difference between the sensing element temperature and the actual temperature of the medium.

Fast Response Time

The Fluke Calibration 1551A-Ex provides a fast response to temperature changes.

The response time is approximately:

20 seconds

under the manufacturer’s specified measurement conditions.

Fast response is particularly useful during field measurements and repeated verification procedures.

Actual response time depends on the medium, immersion depth, temperature difference and thermal conditions.

Measurements in a stirred liquid bath generally provide better thermal transfer than measurements in air.

Large Backlit Display

The Fluke Calibration 1551A-Ex features a large LCD designed for easy reading in laboratory and field environments.

A backlight improves visibility under poor lighting conditions.

The display can show temperature in:

• °C
• °F

Additional display functions allow the user to evaluate temperature changes without requiring an external data acquisition system.

Minimum, Maximum and Trend Functions

The Fluke Calibration 1551A-Ex provides useful measurement functions for monitoring temperature behavior.

Minimum and maximum values can be displayed, making it easier to observe temperature variations.

A trend indicator helps the user determine whether the measured temperature is rising, falling or stable.

These functions are useful when checking whether a temperature source has reached sufficient stability before recording a calibration result.

Integrated Data Logging

The Fluke Calibration 1551A-Ex includes an integrated data logging function.

The thermometer can store up to:

10,000 time-stamped measurements

This allows temperature measurements to be recorded over extended periods without requiring continuous manual documentation.

The logging interval can be configured according to the measurement application.

Data logging is particularly useful for:

• Temperature stability measurements
• Process monitoring
• Calibration bath monitoring
• Dry block monitoring
• Long-term temperature measurements
• Field measurements

Recorded data can subsequently be transferred for documentation and evaluation.

USB Communication

The Fluke Calibration 1551A-Ex supports communication with a computer using an appropriate USB interface cable.

This allows stored measurement data to be transferred for further evaluation and documentation.

The communication cable and related accessories should be checked according to the selected product configuration, as they may not be included with every instrument package.

Battery-Powered Operation

The Fluke Calibration 1551A-Ex is designed for portable operation.

The thermometer is powered by:

3 AAA alkaline batteries

The manufacturer specifies a typical battery life of approximately:

300 hours

without continuous use of the backlight.

Battery operation makes the instrument particularly suitable for field calibration and measurements at locations where mains power is unavailable.

The batteries must meet the requirements specified by Fluke when the instrument is used in hazardous areas.

A Practical Alternative to Mercury Thermometers

The Fluke Calibration Stik Thermometer series was developed as a practical digital alternative to traditional mercury-in-glass thermometers.

Mercury thermometers have historically been used as reference instruments because of their stability and simplicity.

However, mercury presents environmental, safety and handling concerns.

The Fluke Calibration 1551A-Ex provides a modern digital solution with high accuracy, easy readability, data logging and electronic documentation capabilities.

Unlike liquid-in-glass thermometers, there is no need to estimate a value between scale divisions.

The digital display provides a direct temperature reading with 0.01 °C resolution.

Calibration Bath Reference Measurements

The Fluke Calibration 1551A-Ex is well suited for monitoring temperature calibration baths.

The thermometer can be immersed in a suitable liquid bath and used as a reference for comparison with other temperature sensors.

For accurate comparison measurements, the reference thermometer and device under test should be positioned close together and at comparable immersion depths.

Bath stability, temperature uniformity and the calibration uncertainty of the reference thermometer must be considered in the overall measurement uncertainty.

Dry Block Reference Measurements

The thermometer can also be used with suitable dry block temperature calibrators.

The probe should be inserted into a correctly sized insert to provide good thermal contact.

Excessive clearance between the probe and insert can increase temperature differences and measurement uncertainty.

Sufficient immersion depth is also essential.

When high accuracy is required, the axial and radial temperature characteristics of the dry block should be included in the uncertainty analysis.

Technical Highlights

Fluke Calibration 1551A-Ex or 1552A-Ex?

The Fluke Calibration 1551A-Ex and 1552A-Ex belong to the same Stik Thermometer family but cover different temperature ranges.

The Fluke Calibration 1551A-Ex provides a range of:

−50 °C to +160 °C

The Fluke Calibration 1552A-Ex provides a range of:

−80 °C to +300 °C

The 1551A-Ex therefore provides an excellent solution for users working primarily within the lower and medium temperature range.

The 1552A-Ex extends the measurement capability to significantly lower and higher temperatures.

Both models combine reference-level temperature measurement with portable, intrinsically safe construction.

The appropriate model should be selected according to the required temperature range and application.

Calibration Service by europascal

A reference thermometer should be calibrated regularly to maintain reliable and traceable temperature measurements.

europascal provides professional calibration services for temperature measuring instruments and reference thermometers.

When the Fluke Calibration 1551A-Ex is used as a reference thermometer, the uncertainty stated in its calibration certificate should be considered together with other relevant uncertainty contributions.

Depending on the application, these may include temperature source stability, temperature uniformity, immersion effects, repeatability and resolution.

For professional calibration services and metrological traceability, visit the europascal Calibration Service.

Why Choose the Fluke Calibration 1551A-Ex?

The Fluke Calibration 1551A-Ex combines reference-level temperature measurement with a compact and intrinsically safe design.

Its temperature range from −50 °C to +160 °C covers numerous industrial and laboratory applications.

Accuracy of ±0.05 °C throughout the range makes the thermometer suitable for demanding reference measurements.

A resolution of 0.01 °C allows small temperature changes to be observed clearly.

The integrated 200 mm stainless steel probe eliminates the need for a separate thermometer readout and sensor.

Data logging for up to 10,000 measurements provides convenient documentation of temperature measurements.

Battery operation and the compact design make the instrument particularly suitable for mobile calibration applications.

Its intrinsically safe construction provides an important advantage when measurements must be performed in suitable hazardous environments.

For calibration laboratories, process industries and service technicians requiring a portable temperature reference, the Fluke Calibration 1551A-Ex provides an excellent combination of accuracy, safety and ease of use.

europascal supports customers with professional temperature calibration equipment, technical advice and calibration services.

Typical Applications for the Fluke Calibration 1551A-Ex

Typical applications include:

• Reference temperature measurements
• Field temperature calibration
• Process temperature verification
• Calibration bath monitoring
• Dry block calibrator monitoring
• Temperature transmitter verification
• RTD comparison measurements
• Industrial maintenance
• Pharmaceutical manufacturing
• Chemical and petrochemical applications
• Oil and gas applications
• Quality assurance
• Calibration laboratories
• Hazardous-area temperature measurements

The combination of ±0.05 °C accuracy, integrated data logging, portable construction and intrinsically safe operation makes the Fluke Calibration 1551A-Ex an excellent reference thermometer for professional temperature measurement.

Find more Fluke Calibration products here.

Manufacturer information for the Fluke Calibration 1551A-Ex can be found on the official Fluke Calibration website.

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