The Fluke Calibration 5611 is a high-precision, silicone-coated secondary reference thermistor designed for accurate temperature measurements in laboratories, industrial environments and demanding temperature calibration applications.
With a temperature range from 0 °C to +100 °C, a nominal resistance of 10,000 Ω at 25 °C and a calibrated accuracy of ±0.01 °C, the Fluke Calibration 5611 provides excellent measurement performance in a compact and flexible design.
The most important feature of the Fluke Calibration 5611 is its exceptionally small sensing tip.
With a tip diameter of only 1.5 mm, the thermistor can measure temperatures in locations that are difficult or impossible to access with conventional metal-sheathed temperature probes.
The flexible silicone coating makes the Fluke Calibration 5611 particularly suitable for applications requiring a small, lightweight and responsive temperature sensor.
Unlike platinum resistance thermometers, the Fluke Calibration 5611 uses a negative temperature coefficient (NTC) thermistor.
The electrical resistance decreases as temperature increases, providing excellent sensitivity to small temperature changes.
The manufacturer specifies repeatability better than ±0.005 °C and annual drift better than ±0.01 °C under defined conditions.
Each Fluke Calibration 5611 is supplied with individual resistance-temperature calibration data and an interpolation equation.
A calibration traceable to NIST standards is included, while an accredited calibration can be ordered separately.
When combined with a suitable precision thermometer readout, the Fluke Calibration 5611 provides an excellent solution for reference temperature measurements and temperature comparison calibration.
At europascal, the Fluke Calibration 5611 offers a professional solution for precision temperature measurement, laboratory calibration and temperature monitoring applications.
For professional calibration and metrological traceability, visit the europascal Calibration Service.
Your Benefits at a Glance
- High-precision secondary reference thermistor
- Temperature range from 0 °C to +100 °C
- Calibrated accuracy of ±0.01 °C
- Repeatability better than ±0.005 °C
- Annual drift better than ±0.01 °C
- Nominal resistance of 10 kΩ at 25 °C
- Negative temperature coefficient (NTC)
- Extremely small 1.5 mm sensing tip
- Flexible silicone-coated construction
- Fast response to temperature changes
- Suitable for confined measurement locations
- Suitable for small measurement volumes
- Reduced immersion requirements compared with many PRT probes
- Suitable for temperature comparison calibration
- Individual resistance-temperature calibration table
- Calibration table with 0.1 °C increments
- Interpolation equation included
- NIST-traceable calibration included
- Optional accredited calibration
- Different connector configurations available
- Compatible with precision thermometer readouts
- Professional calibration support from europascal
Precision Temperature Measurement from 0 °C to 100 °C
The Fluke Calibration 5611 provides accurate temperature measurements over a defined operating range.
Temperature range: 0 °C to +100 °C
This range covers many important laboratory and industrial applications.
The Fluke Calibration 5611 is particularly suitable for measurements requiring high accuracy near ambient temperature.
Its high temperature sensitivity makes it useful for detecting small temperature differences and fluctuations.
Typical applications include laboratory temperature measurements, temperature comparison calibration, temperature stability monitoring and temperature measurements in confined spaces.
The Fluke Calibration 5611 is designed for applications where a conventional rigid temperature probe may be too large.
Silicone-Coated Thermistor
The Fluke Calibration 5611 features a flexible silicone-coated construction.
Unlike conventional metal-sheathed reference thermometers, the sensing element is protected by a flexible coating.
This provides several advantages.
The sensor can be positioned in confined spaces and locations that are difficult to access.
Its small sensing tip also allows temperature measurements in relatively small measurement volumes.
The silicone coating makes the probe particularly useful for applications requiring flexibility and fast thermal response.
However, the material compatibility of the coating must be considered.
Applications involving silicone oil should be avoided because silicone oil may damage the thermistor.
For measurements requiring chemical resistance to a wide range of liquids, the PTFE-encapsulated Fluke Calibration 5611T may be more appropriate.
Extremely Small 1.5 mm Sensing Tip
One of the most important advantages of the Fluke Calibration 5611 is its small sensing tip.
Tip diameter: 1.5 mm
Tip length: 25.4 mm
The compact dimensions allow the sensor to be positioned in narrow spaces.
The small sensing element also provides a relatively low thermal mass.
This helps the sensor respond quickly to changes in temperature.
The compact design is particularly useful when measuring temperatures in small laboratory equipment or restricted measurement locations.
Fast Temperature Response
The Fluke Calibration 5611 is designed for applications requiring a fast response to temperature changes.
The small sensing element and flexible construction help reduce the thermal mass of the probe.
As a result, the thermistor can respond more quickly than many larger metal-sheathed temperature sensors under comparable conditions.
Fast response is useful when monitoring changing temperature conditions.
However, the actual response time depends on the measurement medium, installation and thermal contact.
For high-accuracy calibration, sufficient time must be allowed for thermal equilibrium.
NTC Thermistor Technology
The Fluke Calibration 5611 uses an NTC thermistor.
NTC stands for:
Negative Temperature Coefficient
The electrical resistance of the sensing element decreases as temperature increases.
This differs from platinum resistance thermometers, which have a positive temperature coefficient.
The Fluke Calibration 5611 has a nominal resistance of:
10,000 Ω at 25 °C
The relatively high resistance and strong temperature dependence provide excellent sensitivity.
This makes NTC thermistors particularly suitable for accurate temperature measurements over a limited temperature range.
High Calibrated Accuracy
The Fluke Calibration 5611 provides excellent calibrated accuracy.
The manufacturer specifies:
±0.01 °C
This specification applies to the supplied resistance-temperature calibration table and interpolation equation.
The actual uncertainty of a complete temperature measurement system depends on additional factors.
These include the connected thermometer readout, measurement conditions, sensor stability and calibration uncertainty.
For professional calibration, all relevant uncertainty contributions must be considered.
Excellent Repeatability
Repeatability is an important characteristic of reference temperature sensors.
The Fluke Calibration 5611 provides excellent repeatability under defined measurement conditions.
The manufacturer specifies:
Better than ±0.005 °C
This characteristic is particularly useful for temperature comparison measurements.
It allows small temperature differences to be evaluated with high reproducibility.
Low Annual Drift
Long-term stability is essential for reliable reference temperature measurements.
The Fluke Calibration 5611 is designed to maintain stable resistance-temperature characteristics.
The manufacturer specifies annual drift of:
Better than ±0.01 °C per year
This specification is stated with a coverage factor of:
k = 3
Regular calibration is recommended to monitor changes in the resistance-temperature characteristic over time.
Individual Resistance-Temperature Calibration
Each Fluke Calibration 5611 is supplied with individual calibration data.
The manufacturer provides a resistance-versus-temperature table.
The calibration table contains values in increments of:
0.1 °C
An interpolation equation is also supplied.
This allows resistance values between the tabulated calibration points to be converted into temperature.
The manufacturer describes interpolation to a resolution of:
0.0001 °C
This interpolation resolution must not be confused with the calibrated accuracy of ±0.01 °C.
Thermistor Temperature Conversion
The relationship between resistance and temperature in an NTC thermistor is nonlinear.
A commonly used mathematical representation is the Steinhart-Hart equation:
1/T = A + B × ln(R) + C × [ln(R)]³
Where:
- T = Absolute temperature in kelvin
- R = Thermistor resistance
- A, B and C = Calibration coefficients
The exact temperature conversion depends on the individual calibration data and the capabilities of the connected thermometer readout.
For accurate measurements, the calibration equation supplied with the probe should be used.
NIST-Traceable Calibration Included
The Fluke Calibration 5611 is supplied with calibration data traceable to NIST standards.
The calibration documentation provides the individual resistance-temperature relationship of the thermistor.
This supports accurate temperature calculation.
The included traceable calibration is not necessarily equivalent to an accredited calibration certificate.
An accredited calibration can be ordered separately.
Optional Accredited Calibration
Fluke Calibration offers optional NVLAP-accredited calibration for the 5611.
The manufacturer specifies optional accredited calibration uncertainties down to:
±0.006 °C
The applicable uncertainty depends on the selected calibration service and calibration conditions.
For demanding metrological applications, the calibration certificate should be reviewed to determine the relevant measurement uncertainty.
Compatible Thermometer Readouts
The Fluke Calibration 5611 is a passive temperature sensor.
It does not include an integrated temperature display.
A compatible precision thermometer readout is required.
Suitable Fluke Calibration instruments include:
- Fluke Calibration 1504
- Fluke Calibration 1523
- Fluke Calibration 1524
- Fluke Calibration 1529
- Fluke Calibration 1560
- Fluke Calibration 1575A
- Fluke Calibration 1590
The appropriate connector configuration must be selected.
Fluke Calibration 5611 with Fluke Calibration 1504
The Fluke Calibration 1504 is a precision thermistor thermometer readout.
When combined with the Fluke Calibration 5611, it provides a compact temperature measurement system.
The readout measures the resistance of the thermistor and converts it into temperature using suitable calibration coefficients.
This combination is useful for laboratory temperature measurements and calibration applications.
Fluke Calibration 5611 with Fluke Calibration 1523
The Fluke Calibration 1523 is a portable reference thermometer readout.
It supports precision thermistors and other temperature sensor technologies.
Combined with the Fluke Calibration 5611, it provides a portable solution for accurate temperature measurements.
The flexible probe construction is particularly useful when measuring temperatures in confined spaces.
Fluke Calibration 5611 with Fluke Calibration 1524
The Fluke Calibration 1524 is a dual-channel reference thermometer readout.
It allows simultaneous measurements using two compatible temperature sensors.
The instrument also provides integrated data logging.
When combined with the Fluke Calibration 5611, it can be used for temperature comparison measurements and temperature stability monitoring.
Available Connector Configurations
The Fluke Calibration 5611 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 connector must be selected according to the thermometer readout.
Fluke Calibration 5611A-11X
The manufacturer lists the silicone-coated version as:
Fluke Calibration 5611A-11X
The model features:
Tip diameter: 1.5 mm
Tip length: 25.4 mm
Temperature range: 0 °C to +100 °C
Lead-wire length: 1.83 m (6 ft)
The letter X identifies the selected connector configuration.
For example, a suitable INFO-CON version can be selected for compatible Fluke Calibration thermometer readouts.
Temperature Comparison Calibration
The Fluke Calibration 5611 is suitable for temperature comparison calibration.
A calibrated reference thermistor and the device under test are placed in a stable temperature environment.
After thermal equilibrium has been reached, the temperature indications 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 depends on the calibration of the reference thermistor, thermometer readout and measurement conditions.
Temperature Measurements in Confined Spaces
The Fluke Calibration 5611 is particularly suitable for measurements in locations where conventional reference thermometers cannot be installed.
Its flexible silicone-coated construction allows the probe to be positioned in narrow openings and small measurement spaces.
The small sensing tip can also reduce the thermal disturbance caused by the measurement probe.
This is useful when measuring temperatures in small laboratory equipment.
The probe must nevertheless be positioned correctly to ensure adequate thermal contact.
Temperature Stability Measurements
The Fluke Calibration 5611 can be used to monitor temperature fluctuations over time.
When connected to a suitable thermometer readout or data acquisition system, the sensor provides accurate resistance measurements.
These measurements can be converted into temperature and recorded.
The resulting data can be used to evaluate temperature stability.
Typical applications include:
- Laboratory temperature monitoring
- Temperature-controlled equipment
- Temperature stability testing
- Temperature comparison measurements
- Research applications
Measurement in Air
The Fluke Calibration 5611 is particularly useful for temperature measurements in air.
Its small sensing element and low thermal mass support a fast response.
The manufacturer also highlights the low self-heating characteristics of its secondary reference thermistors.
However, self-heating depends on the measurement current and thermal conditions.
For high-accuracy air temperature measurements, the excitation current and airflow conditions should be considered.
Technical Highlights
| Feature | Fluke Calibration 5611 |
|---|---|
| Product type | Secondary Reference Thermistor |
| Manufacturer | Fluke Calibration |
| Current model designation | 5611A-11X |
| Sensor technology | NTC Thermistor |
| Temperature range | 0 °C to +100 °C |
| Nominal resistance | 10,000 Ω at 25 °C |
| Calibrated accuracy | ±0.01 °C |
| Repeatability | Better than ±0.005 °C |
| Annual drift | Better than ±0.01 °C per year, k = 3 |
| Optional accredited calibration uncertainty | Down to ±0.006 °C |
| Sensing tip diameter | 1.5 mm |
| Sensing tip length | 25.4 mm |
| Probe construction | Flexible, silicone-coated |
| Lead-wire length | 1.83 m |
| Calibration table | Resistance vs. temperature |
| Calibration table increments | 0.1 °C |
| Interpolation equation | Included |
| Interpolation resolution | 0.0001 °C |
| NIST-traceable calibration | Included |
| Accredited calibration | Optional |
| Integrated display | No |
| Connector | Selected when ordering |
Fluke Calibration 5610 vs. Fluke Calibration 5611
The Fluke Calibration 5610 and 5611 are both precision secondary reference thermistors.
However, their construction differs significantly.
| Feature | Fluke Calibration 5610 | Fluke Calibration 5611 |
|---|---|---|
| Sensor technology | NTC Thermistor | NTC Thermistor |
| Temperature range | 0 °C to 100 °C | 0 °C to 100 °C |
| Nominal resistance | 10 kΩ | 10 kΩ |
| Calibrated accuracy | ±0.01 °C | ±0.01 °C |
| Probe construction | Stainless steel sheath | Silicone-coated flexible probe |
| Probe diameter | 3.2 mm | 1.5 mm at tip |
| Main advantage | Robust immersion probe | Small flexible sensing tip |
| Typical application | Calibration baths | Confined measurement locations |
The Fluke Calibration 5610 is particularly suitable for conventional immersion measurements.
The Fluke Calibration 5611 is ideal for applications requiring a small and flexible sensing element.
Fluke Calibration 5611 vs. Fluke Calibration 5611T
The Fluke Calibration 5611 and 5611T use similar thermistor technology but feature different protective coatings.
| Feature | Fluke Calibration 5611 | Fluke Calibration 5611T |
|---|---|---|
| Temperature range | 0 °C to 100 °C | 0 °C to 100 °C |
| Nominal resistance | 10 kΩ | 10 kΩ |
| Coating | Silicone | PTFE |
| Tip diameter | 1.5 mm | Approx. 3.2 mm |
| Flexible construction | Yes | Yes |
| Lead-wire length | 1.83 m | Approx. 6.1 m |
| Main advantage | Small sensing tip | Moisture-resistant PTFE encapsulation |
| Silicone oil compatibility | Not recommended | Check chemical compatibility |
The Fluke Calibration 5611 is particularly useful where a small sensing tip is required.
The Fluke Calibration 5611T is designed for applications requiring a PTFE-encapsulated probe.
Typical Applications
The Fluke Calibration 5611 is suitable for:
- Precision temperature measurement
- Secondary reference temperature measurement
- Thermistor calibration
- Temperature comparison calibration
- Laboratory temperature monitoring
- Temperature measurements in confined spaces
- Small-volume temperature measurements
- Temperature stability measurements
- Temperature-controlled equipment
- Air temperature measurement
- Research laboratories
- Quality assurance
- Temperature metrology
- Laboratory temperature calibration
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 5611 can be calibrated to verify its individual resistance-temperature characteristic.
When combined with a suitable precision thermometer readout, the thermistor forms part of a traceable temperature measurement system.
The measurement uncertainty depends on the thermistor calibration, thermometer readout and measurement conditions.
For professional calibration and metrological traceability, visit the europascal Calibration Service.
europascal also supports customers in selecting suitable reference thermistors, thermometer readouts and temperature calibration equipment.
Why Choose the Fluke Calibration 5611?
The Fluke Calibration 5611 combines excellent measurement accuracy, fast thermal response and flexible construction in one compact secondary reference thermistor.
Its temperature range from 0 °C to 100 °C covers many important laboratory and industrial applications.
The exceptionally small 1.5 mm sensing tip allows measurements in confined spaces.
The silicone-coated construction provides flexibility and allows the sensor to be positioned where conventional metal-sheathed probes may be unsuitable.
The manufacturer specifies calibrated accuracy of ±0.01 °C, repeatability better than ±0.005 °C and annual drift better than ±0.01 °C.
Individual resistance-temperature calibration data and an interpolation equation are included.
Optional accredited calibration supports demanding metrological applications.
Compatibility with suitable Fluke Calibration thermometer readouts provides flexibility for laboratory and portable measurement systems.
For professional users requiring a compact, flexible and highly accurate reference thermistor, the Fluke Calibration 5611 provides an excellent combination of performance, sensitivity and versatility.
europascal supports customers with reference temperature probes, temperature calibration equipment and professional calibration services.
