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Fluke Calibration 9172 Metrology Well, 35 to 425C, with Insert
Fluke Calibration 9172 Metrology Well, 35 to 425C, with Insert

Our Price: $7,150.00

Quantity in Stock:1
Product Code: 9172


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  • Best/performing industrial heat sources (accuracy, stability, uniformity) in the world
  • Immersion depth to 203 mm (8 in)
  • Optional ITS/90 reference input reads PRTs to ±0.006 °C
  • Temperature range from /45 °C to 700 °C
  • Includes Insert A, B, C, D, E or F

With groundbreaking new pro-prietary electronics from Fluke Calibration (patents pending), Metrology Wells let you bring lab-quality performance into whatever field environment you might work in. New analog and digital control techniques provide stability as good as ±0.005°C. And with dual-zone control, axial (or "vertical") uniformity is as good as ±0.02°C over a 60 mm (2.36 in) zone. (That’s 60 mm!) Such performance doesn’t exist anywhere else outside of fluid baths.

In short, there are six critical components of performance in an industrial heat source (which the European metrology community explains, for example, in the document EA-10/13): calibrated display accuracy, stability, axial (vertical) uniformity, radial (well-to-well) uniformity, impact from loading, and hysteresis. We added a seventh in the form of a legitimate reference thermometer input and created an entirely new product category: Metrology Wells.

By the way, Metrology Wells are the only products on the market supported by published specifications addressing every performance category in the EA-10/13. Our specs aren’t just hopes or guidelines. They apply to every Metrology Well we sell.

If you need more depth, the Fluke Calibration 9171 Series provides 203mm (8 in) of immersion over temperatures from –30°C all the way to 155°C with full-range stability of ±0.005°C. Just like the Fluke Calibration 9170, this dry-well has exceptional axial and radial uniformity. The display of the 9171 is calibrated to an accuracy of ±0.1°C over its full range.

Display accuracy
Dry-wells are typically calibrated by inserting a calibrated PRT into one of the wells and making adjustments to the calibrator’s internal control sensor based on the readings from the PRT. This has limited value because the unique characteristics of the reference PRT, which essentially become “calibrated into" the calibrator, are often quite different from the thermometers tested by the calibrator. This is complicated by the presence of significant thermal gradients in the block and inadequate sensor immersion into blocks that are simply too short.

Temperature gradients, loading effects, and hysteresis have been minimized to make the calibration of the display much more meaningful. The Fluke Calibration 9170 Series Metrology Well Calibrators uses only traceable, accredited PRTs to calibrate Metrology Wells and our proprietary electronics consistently demonstrate repeatable accuracy more than ten times better than our specs, which range from ±0.1°C at the most commonly used temperatures to ±0.25°C at 661°C. For even better accuracy, Fluke Calibration 9171 Metrology Well Calibrators may be ordered with built-in electronics for reading external PRTs with ITS-90 characterizations.

Heat sources from Fluke Calibration have long been known as the most stable heat sources in the world. The Fluke Calibration 9171 Series only gets better with Metrology Wells. Both low-temperature units are table to ±0.005°C over their full range. Better stability can only be found in fluid baths and primary fixed-point devices. The “off-the-shelf controllers" used by most dry-well manufacturers simply can’t provide this level of performance.

Axial uniformity
The Fluke Calibration 9170 Series EA-10/13 document suggests that dry-wells should include a zone of maximum temperature homogeneity, which extends for 40 mm (1.54 in), usually at the bottom of a well. Metrology Wells, however, combine our unique electronics with dual-zone control and more well depth than is found in dry-wells to provide homogeneous zones over 60 mm (2.36 in). Vertical gradients in these zones range from ±0.02°C at 0°C to ±0.4°C at 700°C

Radial uniformity
Radial uniformity is the difference in temperature between one well and another well. For poorly designed heat sources, or when large-diameter probes are used, these differences can be very large. For Metrology Wells, we define our specification as the largest temperature difference between the vertically homogeneous zones of any two wells that are each 6.4 mm (0.25 in) in diameter or smaller. The cold units (9170 and 9171) provide radial uniformity of ±0.01°C.

Loading is defined as the change in temperature sensed by a reference thermometer inserted into the bottom of a well after the rest of the wells are filled with thermometers, too. For Metrology Wells, loading effects are minimized for the same reasons that axial gradients are minimized. We use deeper wells than found in dry-wells. And we utilize proprietary dual-zone controls. Loading effects are as minimal as ±0.005°C in the cold units.

Thermal hysteresis exists far more in internal control sensors than in good-quality reference PRTs. It is evidenced by the difference in two external measurements of the same set-point tempera-ture when that temperature is approached from two different directions (hotter or colder) and is usually largest at the midpoint of a heat source’s temperature range. It exists because control sensors are typically designed for ruggedness and do not have the “strain free” design characteristics of SPRTs, or even most PRTs. For Hart Scientific 9171 Metrology Wells, hysteresis effects range from 0.025°C to 0.07°C.

Immersion depth
Immersion depth matters. Not only does it help minimize axial gradient and loading effects, it helps address the unique immersion characteristics of each thermometer tested in the heat source. Those characteristics include the location and size of the actual sensor within the probe, the width and thermal mass of the probe, and the lead wires used to connect the sensor to the outside world.

Other great features
A large LCD display, numeric keypad, and on-screen menus make use of Metrology Wells simple and intuitive. The display shows the block temperature, built-in reference thermometer temperature, cutout temperature, stability criteria, and ramp rate. The user interface can be configured to display in English, French, or Chinese.

All four models come with an RS-232 serial interface and the Model 9930, Interface-it software. All are also compatible with Model 9938 MET/TEMP II software for completely automated calibrations of RTDs, thermocouples, and thermistors.

Even without a PC, Metrology Wells have four different preprogrammed calibration tasks that allow up to eight temperature set points with “ramp and soak" times between each. There is an automated “switch test" protocol that zeros in on the “dead-band" for thermal switches. And a dedicated °C/°F button allows for easy switching of temperature units. Any of six standard inserts may be ordered with each unit, accommodating a variety of metric and imperial-sized probe diameters.


(at 23 °C ambient)
–45 °C to 140 °C
(–49 °F to 284 °F)
–30 °C to 155 °C
(–22 °F to 311 °F)
35 °C to 425 °C
(95 °F to 797 °F)
50 °C to 700 °C†
(122 °F to 1292 °F)
Display Accuracy± 0.1 °C full range± 0.1 °C: 35 °C to 100 °C
± 0.15 °C: 100 °C to 225 °C
± 0.2 °C: 225 °C to 425 °C
± 0.2 °C: 50 °C to 425 °C
± 0.25 °C: 425 °C to 660 °C
Stability± 0.005 °C full range± 0.005 °C: 35 °C to 100 °C
± 0.008 °C: 100 °C to 225 °C
± 0.01 °C: 225 °C to 425 °C
± 0.005 °C: 50 °C to 100 °C
± 0.01 °C: 100 °C to 425 °C
± 0.03 °C: 425 °C to 700 °C
Axial Uniformity
(60 mm)
± 0.1 °C at –45 °C
± 0.04 °C at –35 °C
± 0.02 °C at 0 °C
± 0.07 °C at 140 °C
± 0.025 °C at –30 °C
± 0.02 °C at 0 °C± 0.07 °C at 155 °C
± 0.05 °C: 35 °C to 100 °C
± 0.1 °C: 100 °C to 225 °C
± 0.2 °C: 225 °C to 425 °C
± 0.1 °C: 50 °C to 100 °C
± 0.25 °C: 100 °C to 425 °C± 0.4 °C: 425 °C to 700 °C
Radial Uniformity± 0.01 °C full range± 0.01 °C: 35 °C to 100 °C
± 0.02 °C: 100 °C to 225 °C
± 0.025 °C: 225 °C to 425 °C
± 0.01 °C: 50 °C to 100 °C
± 0.025 °C: 100 °C to 425 °C
± 0.04 °C: 425 °C to 700 °C
Loading Effect
(with a 6.35 mm
reference probe and
three 6.35 mm probes)
± 0.02 °C at –45 °C
± 0.005 °C at –35 °C
± 0.01 °C at 140 °C
± 0.005 °C at –30 °C
± 0.005 °C at 0 °C
± 0.01 °C at 155 °C
± 0.01 °C full range± 0.02 °C at 425 °C
± 0.04 °C at 700 °C
Hysteresis0.025 °C0.04 °C0.07 °C
Well Depth160 mm (6.3 in)203 mm (8 in)
Resolution0.001 °C
DisplayLCD, °C or °F, user-selectable
Key Pad
Ten key with decimal and +/- button. Function keys, menu key, and °C / °F key.
Cooling Time44 min: 23 °C to –45 °C
19 min: 23 °C to –30 °C
19 min: 140 °C to 23 °C
30 min: 23 °C to –30 °C
25 min: 155 °C to 23 °C
220 min: 425 °C to 35 °C
100 min: 425 °C to 100 °C
235 min: 700 °C to 50 °C
153 min: 700 °C to 100 °C
Heating Time32 min: 23 °C to 140 °C
45 min: –45 °C to 140 °C
44 min: 23 °C to 155 °C
56 min: –30 °C to 155 °C
27 min: 35 °C to 425 °C46 min: 50 °C to 700 °C
Size (HxWxD)366 x 203 x 323 mm (14.4 x 8 x 12.7 in)


14.2 kg (31.5 lb)

15 kg (33 lb)

13.2 kg (29 lb)

15 kg (33 lb)

Power115 V ac (± 10 %), or
230 V ac (± 10 %), 50/60 Hz, 550 W
115 V ac (± 10 %), or
230 V ac (± 10 %), 50/60 Hz, 1025 W
Computer InterfaceRS-232 Interface with 9930 Interface-it control software included
Traceable CalibrationData at –45 °C, 0 °C, 50 °C, 100 °C, and 140 °CData at –30 °C, 0 °C, 50 °C, 100 °C, and 155 °CData at 100 °C, 150 °C, 250 °C, 350 °C, and 425 °CData at 100 °C, 200 °C, 350 °C, 500 °C, and 660 °C
†Calibrated to 660 °C; reference thermometer recommended at higher temperatures.


Built-in Reference Input
Temperature Range–200 °C to 962 °C (–328 °F to 1764 °F)
Resistance Range0 Ω to 400 Ω, auto-ranging
CharacterizationsITS-90 subranges 4, 6, 7, 8, 9, 10, and 11 Callendar-Van Dusen (CVD): R0, a, b, d
Resistance Accuracy0 Ω to 20 Ω: 0.0005 W
20 Ω to 400 Ω: 25 ppm
Temperature Accuracy
(does not include probe uncertainty)
10 Ω PRTs:
± 0.013 °C at 0 °C
± 0.014 °C at 155 °C
± 0.019 °C at 425 °C
± 0.028 °C at 700 °C
25 Ω and 100 Ω PRTs:
± 0.005 °C at –100 °C
± 0.007 °C at 0 °C
± 0.011 °C at 155 °C
± 0.013 °C at 225 °C
± 0.019 °C at 425 °C
± 0.027 °C at 661 °C
Resistance Resolution0 Ω to 20 Ω: 0.0001 Ω
20 Ω to 400 Ω: 0.001 Ω
Measurement Period1 second
Probe Connection4-wire with shield, 5-pin DIN connector
CalibrationNVLAP accredited calibration included

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