The Fluke Calibration 5615 is a high-precision secondary reference platinum resistance thermometer (PRT) designed for accurate temperature measurements and professional calibration applications. With a temperature range of up to −200 °C to +420 °C, excellent measurement stability and a robust Inconel 600 sheath, the Fluke Calibration 5615 provides reliable reference measurements in calibration laboratories, industrial facilities and temperature metrology applications.
The Fluke Calibration 5615 combines the accuracy of a reference-grade platinum resistance thermometer with the durability required for everyday calibration work. Its sensing element consists of high-purity platinum wire and is designed to minimize mechanical stress, hysteresis and temperature drift.
Depending on the selected version, the thermometer is available with probe lengths of 152 mm, 229 mm or 305 mm. Different probe diameters and connector configurations allow the instrument to be adapted to various calibration systems.
A major advantage of the Fluke Calibration 5615 is its individual ISO/IEC 17025 accredited calibration, which is included with the probe. The calibration provides ITS-90 coefficients and documented measurement results for traceable temperature measurements.
The Fluke Calibration 5615 is particularly suitable for comparison calibration in liquid calibration baths, dry-block calibrators and other stable temperature sources.
When connected to a suitable precision thermometer readout, the Fluke Calibration 5615 forms a highly accurate reference temperature measurement system.
europascal supports customers in selecting suitable reference thermometers, temperature calibration equipment and complete calibration systems.
For professional temperature calibration services, visit the europascal Calibration Service.
Your Benefits at a Glance
- High-precision secondary reference platinum resistance thermometer
- Temperature range up to −200 °C to +420 °C
- Calibrated accuracy of ±0.012 °C at 0 °C
- Reference-grade platinum sensing element
- Platinum purity of 99.999%
- Nominal resistance of 100 Ω at 0 °C
- Excellent short-term repeatability
- Low temperature drift
- Robust Inconel 600 sheath
- Four-wire resistance measurement
- Available in three probe lengths
- Two probe diameters available
- Fast thermal response
- Suitable for liquid calibration baths
- Suitable for dry-block temperature calibrators
- Suitable for laboratory reference measurements
- Individual ITS-90 calibration coefficients
- Accredited calibration included
- Multiple connector configurations
- Compatible with precision thermometer readouts
- Professional support from europascal
Precision Temperature Measurement from −200 °C to +420 °C
The Fluke Calibration 5615 is designed for accurate temperature measurements over a wide temperature range.
Depending on the selected version, the operating temperature range is:
−200 °C to +420 °C
This range covers cryogenic temperature measurements, low-temperature calibration, ambient temperature measurements and elevated-temperature industrial applications.
The Fluke Calibration 5615 is available in three versions.
The 5615-6 covers temperatures from −200 °C to +300 °C.
The 5615-9 and 5615-12 cover temperatures from −200 °C to +420 °C.
The different versions allow the reference thermometer to be selected according to the required temperature range, immersion depth and calibration equipment.
Secondary Reference Platinum Resistance Thermometer
The Fluke Calibration 5615 is designed as a secondary reference temperature standard.
Secondary reference thermometers are used to transfer temperature values from higher-level standards to working standards and industrial temperature sensors.
The Fluke Calibration 5615 provides the accuracy and stability required for professional temperature comparison measurements.
A calibrated reference thermometer and a device under test are placed in the same stable temperature source.
After thermal equilibrium has been reached, the reference temperature and the indication of the device under test are recorded.
The difference between the two values determines the indication error.
This method is widely used in calibration laboratories and industrial quality assurance.
Reference-Grade Platinum Sensing Element
The Fluke Calibration 5615 uses a precision platinum resistance sensing element.
The manufacturer specifies a platinum purity of:
99.999%
The high-purity platinum wire is wound into a coil and supported by a specially designed ceramic structure.
This construction minimizes mechanical stress on the sensing element.
Mechanical stress can change the resistance characteristics of platinum and introduce measurement errors.
The carefully supported sensing element helps minimize hysteresis and improves measurement stability.
The Fluke Calibration 5615 therefore provides excellent performance during repeated temperature calibration cycles.
Nominal Resistance of 100 Ω
The Fluke Calibration 5615 has a nominal resistance of:
100 Ω at 0 °C
The manufacturer specifies a temperature coefficient of:
0.0039250 Ω/Ω/°C
This characteristic differs from the conventional industrial Pt100 coefficient of 0.00385 Ω/Ω/°C.
For accurate measurements, the individual calibration coefficients supplied with the thermometer should be used.
A compatible precision thermometer readout can convert the measured resistance into temperature using the appropriate calibration function.
High Calibrated Accuracy
The Fluke Calibration 5615 provides excellent calibrated accuracy.
The manufacturer specifies the following values:
| Temperature | Accuracy |
|---|---|
| −200 °C | ±0.024 °C |
| 0 °C | ±0.012 °C |
| +420 °C | ±0.035 °C |
These values include the calibration contribution and the specified drift contribution under the manufacturer’s defined conditions.
They must not be confused with the total measurement uncertainty of a complete calibration system.
The measurement uncertainty also depends on the connected thermometer readout, temperature source and measurement conditions.
Excellent Short-Term Repeatability
Repeatability is an important characteristic of reference temperature probes.
The Fluke Calibration 5615 provides excellent repeatability during repeated temperature cycles.
The manufacturer specifies short-term repeatability of:
±0.009 °C at 0.01 °C
This value includes hysteresis under the specified test conditions.
Good repeatability contributes to reliable calibration results.
It is particularly important when the reference thermometer is repeatedly exposed to different temperatures.
Low Temperature Drift
Long-term stability is essential for professional reference temperature measurements.
The Fluke Calibration 5615 is designed to minimize changes in the resistance-temperature relationship over time.
The manufacturer specifies drift of:
±0.007 °C at 0.01 °C
This specification applies after the defined high-temperature exposure procedure.
Regular verification and recalibration help identify changes in the sensor characteristics.
Robust Inconel 600 Sheath
The Fluke Calibration 5615 features a robust Inconel 600 sheath.
Inconel 600 is a nickel-based alloy suitable for demanding temperature applications.
The sheath provides mechanical protection for the precision platinum sensing element.
It also supports repeated use in laboratory and industrial calibration environments.
The sensing element is protected by a high-purity ceramic housing and a hermetic glass seal.
This construction helps prevent moisture and contaminants from entering the sensing element.
Four-Wire Resistance Measurement
The Fluke Calibration 5615 uses a four-wire electrical connection.
Four-wire measurement is particularly important for precision platinum resistance thermometers.
In a conventional two-wire connection, the resistance of the connecting leads contributes to the measured resistance.
This can introduce significant temperature measurement errors.
Four-wire measurement separates the current-carrying conductors from the voltage-sensing conductors.
This minimizes the influence of connecting lead resistance.
The result is a more accurate measurement of the platinum sensing element.
Available Probe Versions
The Fluke Calibration 5615 is available in three different probe configurations.
Fluke Calibration 5615-6
The Fluke Calibration 5615-6 features a compact probe design.
Temperature range: −200 °C to +300 °C
Probe length: 152 mm
Probe diameter: 4.76 mm
This version is particularly suitable for compact calibration setups and applications requiring a shorter reference thermometer.
Fluke Calibration 5615-9
The Fluke Calibration 5615-9 provides an extended temperature range.
Temperature range: −200 °C to +420 °C
Probe length: 229 mm
Probe diameter: 4.76 mm
The slim probe design provides flexibility when using dry-block calibrators and liquid calibration baths.
Fluke Calibration 5615-12
The Fluke Calibration 5615-12 is the longest version.
Temperature range: −200 °C to +420 °C
Probe length: 305 mm
Probe diameter: 6.35 mm
This version is particularly suitable for applications requiring greater immersion depth.
Fast Thermal Response
The Fluke Calibration 5615 provides a typical response time of:
9 seconds
The manufacturer specifies this value according to ASTM E644.
A fast response helps reduce waiting time during temperature measurements.
However, the actual response depends on the measurement medium, installation and thermal conditions.
For high-accuracy calibration, sufficient time must be allowed for complete thermal equilibrium.
ITS-90 Calibration Coefficients
The Fluke Calibration 5615 is supplied with individual ITS-90 calibration coefficients.
ITS-90 is the International Temperature Scale of 1990.
It provides a standardized basis for high-accuracy temperature measurements.
The individual coefficients describe the resistance-temperature relationship of the calibrated platinum resistance thermometer.
When these coefficients are entered into a compatible thermometer readout, the instrument can calculate temperature according to the individual characteristics of the probe.
This provides better measurement accuracy than using a generic nominal resistance-temperature characteristic.
Accredited Calibration Included
An important advantage of the Fluke Calibration 5615 is that an accredited calibration is included.
Each probe is supplied with an individual calibration according to ISO/IEC 17025.
The calibration provides documented measurement results and metrological traceability.
The manufacturer also supplies a resistance table with values in increments of 1 °C.
This documentation supports the use of the Fluke Calibration 5615 as a professional secondary reference thermometer.
The actual calibration uncertainty depends on the individual certificate and the calibration laboratory.
Compatible Thermometer Readouts
The Fluke Calibration 5615 is a passive platinum resistance thermometer.
It does not include an integrated temperature display.
A suitable precision thermometer readout is required.
Compatible instruments include:
- Fluke Calibration 1502A
- Fluke Calibration 1523
- Fluke Calibration 1524
- Fluke Calibration 1529
- Fluke Calibration 1560
- Other compatible precision resistance thermometer readouts
The appropriate connector configuration must be selected.
Available Connector Configurations
The Fluke Calibration 5615 is available with different connector options.
| Connector Code | Connection Type |
|---|---|
| A | INFO-CON for Fluke 914X |
| B | Bare wire |
| D | 5-pin DIN |
| G | Gold pins |
| J | Banana plugs |
| L | Mini spade lugs |
| M | Mini banana plugs |
| P | INFO-CON for Fluke 1523/1524 |
| S | Spade lugs |
The correct connector should be selected according to the thermometer readout.
Temperature Comparison Calibration
The Fluke Calibration 5615 is particularly suitable for comparison calibration.
During comparison calibration, the reference thermometer and the device under test are exposed to the same nominal temperature.
A suitable temperature source may be a liquid calibration bath or a dry-block calibrator.
After thermal equilibrium has been reached, both temperature values are recorded.
The indication error is calculated as:
ΔT = T_DUT − T_REF
Where:
- ΔT = Temperature indication error
- T_DUT = Temperature indicated by the device under test
- T_REF = Reference temperature
The measurement uncertainty must include all relevant contributions of the reference thermometer, readout and temperature source.
Use in Liquid Calibration Baths
The Fluke Calibration 5615 is suitable for use in compatible liquid calibration baths.
Liquid baths provide stable and uniform temperature conditions.
The reference thermometer and sensors under test can be positioned close to one another.
This helps reduce uncertainty caused by temperature gradients.
The Fluke Calibration 5615 provides accurate reference measurements for professional calibration procedures.
Use in Dry-Block Calibrators
The Fluke Calibration 5615 can also be used with suitable dry-block temperature calibrators.
The reference thermometer is inserted into an appropriate measurement opening.
It measures the temperature of the calibration zone.
This allows the actual reference temperature to be determined independently of the internal control sensor of the dry-block calibrator.
The correct immersion depth and thermal contact are important for accurate results.
Immersion Depth and Stem Conduction
Immersion depth is an important factor in precision temperature measurement.
If a reference thermometer is not immersed sufficiently, heat can be conducted along the probe stem.
This can cause a difference between the temperature of the sensing element and the actual temperature of the calibration medium.
The resulting measurement error is commonly called stem conduction error.
The Fluke Calibration 5615 is available in different lengths to accommodate different immersion requirements.
The correct version should be selected according to the calibration equipment and required measurement uncertainty.
Temperature Stability Measurements
The Fluke Calibration 5615 can be used to evaluate the temperature stability of calibration equipment.
When connected to a suitable thermometer readout or data acquisition system, the probe provides precise resistance measurements.
These measurements can be converted into temperature and recorded over time.
The resulting data can be used to evaluate temperature fluctuations.
Typical applications include stability measurements of liquid calibration baths and dry-block calibrators.
Technical Highlights
| Feature | Fluke Calibration 5615 |
|---|---|
| Product type | Secondary Reference Platinum Resistance Thermometer |
| Manufacturer | Fluke Calibration |
| Temperature range, 5615-6 | −200 °C to +300 °C |
| Temperature range, 5615-9 | −200 °C to +420 °C |
| Temperature range, 5615-12 | −200 °C to +420 °C |
| Sensor type | Reference-grade platinum resistance thermometer |
| Platinum purity | 99.999% |
| Nominal resistance at 0 °C | 100 Ω ±0.10 Ω |
| Temperature coefficient | 0.0039250 Ω/Ω/°C |
| Accuracy at −200 °C | ±0.024 °C |
| Accuracy at 0 °C | ±0.012 °C |
| Accuracy at +420 °C | ±0.035 °C |
| Short-term repeatability | ±0.009 °C at 0.01 °C |
| Drift | ±0.007 °C at 0.01 °C |
| Sensor length | 28 mm |
| Sensor position | 6.9 mm ±3.3 mm from tip |
| Sheath material | Inconel 600 |
| Sheath diameter, 5615-6 | 4.76 mm |
| Sheath diameter, 5615-9 | 4.76 mm |
| Sheath diameter, 5615-12 | 6.35 mm |
| Probe length, 5615-6 | 152 mm |
| Probe length, 5615-9 | 229 mm |
| Probe length, 5615-12 | 305 mm |
| Response time | 9 seconds typical |
| Electrical connection | Four-wire |
| Lead-wire length | 1.83 m |
| Transition junction temperature range | −50 °C to +200 °C |
| Lead-wire temperature range | −50 °C to +200 °C |
| ITS-90 coefficients | Included |
| Accredited calibration | Included |
| Integrated display | No |
Fluke Calibration 5615 vs. Industrial Pt100
The Fluke Calibration 5615 provides several advantages compared with conventional industrial Pt100 sensors.
Its reference-grade platinum sensing element is designed for excellent stability and repeatability.
The individual ITS-90 calibration coefficients allow accurate temperature conversion.
The robust Inconel sheath provides mechanical protection.
The included accredited calibration makes the probe suitable for professional reference temperature measurements.
Unlike a conventional industrial Pt100, the Fluke Calibration 5615 is specifically designed as a secondary reference thermometer.
Typical Applications
The Fluke Calibration 5615 is suitable for:
- Secondary reference temperature measurements
- Temperature calibration laboratories
- Platinum resistance thermometer calibration
- Pt100 calibration
- Temperature comparison calibration
- Liquid calibration baths
- Dry-block temperature calibrators
- Cryogenic temperature measurements
- Temperature stability measurements
- Temperature uniformity measurements
- Industrial temperature sensor calibration
- Laboratory reference measurements
- Research and development
- Quality assurance
- Temperature metrology
Calibration by europascal
Regular calibration is essential for maintaining reliable temperature measurement results.
europascal provides professional calibration services for temperature measuring instruments and reference temperature measurement systems.
The Fluke Calibration 5615 can be used as a calibrated reference thermometer in professional temperature calibration applications.
When combined with a suitable precision thermometer readout, it forms a traceable reference temperature measurement system.
The complete measurement uncertainty depends on the calibration uncertainty of the probe, readout performance, sensor stability and measurement conditions.
For professional calibration and metrological traceability, visit the europascal Calibration Service.
europascal also supports customers in selecting suitable reference thermometers, calibration baths, dry-block calibrators and complete temperature calibration systems.
Why Choose the Fluke Calibration 5615?
The Fluke Calibration 5615 combines high measurement accuracy, excellent stability and robust construction in a professional secondary reference thermometer.
Its reference-grade platinum sensing element provides reliable temperature measurements.
The temperature range of up to −200 °C to +420 °C covers many laboratory and industrial calibration applications.
Three different probe lengths allow the thermometer to be adapted to different calibration equipment.
The Inconel 600 sheath provides mechanical durability.
Four-wire resistance measurement minimizes the influence of connecting lead resistance.
Individual ITS-90 coefficients and an accredited calibration are included.
This makes the Fluke Calibration 5615 an excellent choice for professional temperature comparison calibration and reference temperature measurements.
europascal supports customers with reference thermometers, temperature calibration equipment and professional calibration services.
