Temperature Calibrators: Dry Wells, Baths & Furnaces

Dry-block, bath, and furnace temperature calibrators for industrial sensors and transmitters — JOFRA, Additel, and related lines, with ISO/IEC 17025 accredited calibration available on most instruments.

What a temperature calibrator does

A temperature calibrator creates a stable temperature environment so you can compare a thermometer, RTD, thermocouple, or transmitter against a known reference. Dry-wells (dry-blocks) are common in the field; baths and furnaces cover wider or higher ranges.

Dry-well, bath, and furnace

• Dry-block / dry-well — portable or benchtop inserts for sensors; fast and clean for many industrial jobs.
• Liquid baths — better uniformity for some lab comparisons (when available in-line).
• Furnaces / high-temp blocks — thermocouple and high-temperature work (e.g. Additel furnace platforms).

Choosing a calibrator

• Range and stability — cover the UUT with margin; watch axial gradients on inserts.
• Insert / well diameter — must fit your probes without excessive air gap.
• Reference probe inputs — when you use an external SPRT/RTD reference.
• Documenting / automation — useful for multi-point procedures and paperless as-found/as-left.

Brands in this category

AMETEK JOFRA dry wells and other AMETEK temperature calibrator models, Additel temperature calibrators and furnaces, plus accessories called out on each product page.

AMETEK JOFRA dry well series compared

AMETEK describes its JOFRA portable temperature calibrator series as follows (accuracies are the best figure AMETEK quotes for each series):

• RTC reference calibrators: highest accuracy, advanced temperature control, and patented Dynamic Load Compensation (DLC) for temperature uniformity. Examples: RTC-156, RTC-700.
• RTCt: the newer RTC generation with enhanced connectivity, dual sensor inputs and an expanded temperature range. Example: RTCt-156.
• PTC professional calibrators: accuracies down to ±0.06 °C, ranges from −90 °C to 660 °C. Example: PTC-155.
• CTC compact calibrators: accuracies down to ±0.2 °C, ranges from −25 °C to 1205 °C, with buttons for switch test and auto stepping. Example: CTC-1205.
• MTC marine calibrators: accuracies down to ±0.9 °C, 28 °C to 650 °C, built for the maritime industry with a three-year calibration interval. See the MTC-650.
• ETC easy calibrators: accuracies down to ±0.5 °C, −10 °C to 400 °C, for fast field checks when the highest accuracy isn't required. See the JOFRA ETC.

Dry well calibrators and furnaces on this site

• Additel 875 Series — ADT875-155, -350 and -660 dry well calibrators and the ADT875-1210 thermocouple furnace; Additel 878 reference dry well / furnace; Additel 850 laboratory furnace; Additel 835 portable bath.
• JOFRA (AMETEK) — RTC-156, RTC-159, RTC-168, RTC-250 and RTC-700 reference calibrators; PTC-155, PTC-425 and PTC-660 professional calibrators; CTC-155, CTC-660 and CTC-1205 compact calibrators; ETC series.
• REED — R2900 dry block calibrator.
• RTD / thermocouple signal calibrators (PIE) — PIE 311, PIE 422 and PIE 525B.

Pair with reference temperature sensors and temperature indicators.

Dry well calibrator buying guide

A dry well (dry-block) calibrator heats or cools a metal block with bored inserts, so the sensor under test sits beside a reference in a stable temperature. Use the steps below to narrow the choice. Ranges and features are taken from each manufacturer's published specifications.

1. Start with the temperature range

• Below ambient: the JOFRA RTC-159 reaches −100 °C, the widest cold range in the RTC family. The JOFRA PTC-125 covers −90 to 125 °C, and the Additel ADT875-155 −40 to 155 °C.
• Mid range (to about 425 °C): the JOFRA CTC-350 and ADT875-350 cover up to 350 °C. The JOFRA PTC-425 (33 to 425 °C) is used for sterilization-tunnel and process-validation sensors.
• High range (to about 700 °C): the JOFRA RTC-700 covers 33 to 700 °C with triple-zone control. The ADT875-660 and JOFRA CTC-660 reach 660 °C, and the JOFRA CTC-652 adds 190 mm immersion depth for long industrial sensors.
• Thermocouple furnaces (above 1,000 °C): the ADT875-1210 and Additel 878-1210 (100 to 1210 °C) and the JOFRA CTC-1205 (100 to 1205 °C). For the lab, the horizontal Additel 850 runs 100 to 1200 °C with ±0.1 °C stability.

2. Dry block, liquid bath, or both

Dry blocks are clean and fast for straight probes. Sanitary, short, or irregular sensors are easier to calibrate in liquid.

• The Additel 835 portable bath has a 90 × 90 mm opening, in −30 to 150 °C or 33 to 250 °C versions.
• The JOFRA RTC-158, RTC-250 and RTC-168 combine a dry block and a liquid bath in one unit. The RTC-168 is designed for large sanitary flange sensors.

3. Choose the accuracy tier

• AMETEK ranks its JOFRA series from RTC (reference) through PTC (to ±0.06 °C), CTC (to ±0.2 °C) and ETC (to ±0.5 °C).
• The Additel 878 is the reference-grade counterpart to the 875 Series.
• Buy the tier your procedure's test uncertainty ratio needs, rather than the highest one available.

4. Uniformity, loading and electronics

• The JOFRA RTC and RTCt use patented Dynamic Load Compensation (DLC) to keep the well uniform when several sensors are loaded. The PTC uses active dual-zone control.
• The Additel 875 and 878 accept optional Process Calibrator (PC) electronics, so one instrument can read the reference and the unit under test.
• The JOFRA RTCt-156 adds a touchscreen and Wi-Fi remote control. CTC models include one-key switch test and auto-step.

5. Infrared thermometers are a separate case

Non-contact instruments need a flat radiating target, not a well. See the REED BX-500 infrared temperature calibrator or the infrared version of the JOFRA ETC.

More models in this category

• JOFRA CTC-350 Compact Temperature Calibrator: compact dry-block calibrator, 28 to 350°C, with one-key switch test and auto-step functions.
• JOFRA CTC-652 Compact Temperature Calibrator: compact dry-block calibrator, 28 to 650°C, with 190 mm immersion depth for long industrial sensors.
• JOFRA PTC-125 Professional Temperature Calibrator: professional dry-block calibrator, −90 to 125°C, with active dual-zone control for lab-grade field work.
• JOFRA PTC-350 Professional Temperature Calibrator: professional dry-block calibrator for mid-range industrial work, with active dual-zone control and fast heating.
• JOFRA RTC-157 Reference Temperature Calibrator: portable reference dry-block calibrator, −45 to 155°C, with patented DLC and dual-zone temperature control.
• JOFRA RTC-158 Reference Temperature Calibrator: combination dry-block and liquid-bath reference calibrator, −22 to 155°C, with patented DLC.
• JOFRA RTC-187 Reference Temperature Calibrator: portable reference dry-block calibrator, −45 to 180°C, with patented DLC and dual-zone control.
• JOFRA RTCt-157 Reference Temperature Calibrator: reference dry-block calibrator, −45 to 155°C, with touchscreen workflows, Wi-Fi, dual-sensor inputs, and DLC.
• JOFRA RTCt-168 Reference Temperature Calibrator: combination dry-block and bath calibrator, −30 to 165°C, with touchscreen control, Wi-Fi, and DLC.
• PIE 211 Automated RTD Calibrator
• PIE 311Plus Diagnostic RTD and Milliamp Calibrator
• PIE 322 Thermocouple Calibrator: thermocouple calibrator for field thermocouple source and measure.
• PIE 422Plus Diagnostic TC and mA Calibrator: diagnostic thermocouple and milliamp calibrator.
• PIE 510B RTD Simulator: single-type RTD simulator for RTD calibration and simulation.
• PIE 511B RTD Simulator: ten-type RTD simulator for RTD calibration and simulation.
• PIE 520B Thermocouple Source: single-type thermocouple source for loop checks and troubleshooting.
• PIE 521B Thermocouple Source: fourteen-type thermocouple source for thermocouple simulation.
• REED BX-500 Infrared Temperature Calibrator: for calibrating non-contact temperature instruments (infrared thermometers, pyrometers and thermal imagers).
• REED R2815 Temperature Calibrator: accurately sources and measures 11 thermocouple types, including A, B, C, D, E, J, K, N, R, S, T.

Frequently asked questions

Is a dry well the same as a dry-block calibrator?

Yes. Both names describe a heated or cooled metal block with inserts that hold the sensor under test beside a reference sensor. JOFRA calls its models dry-block calibrators, and Additel uses dry well.

Which dry well calibrator reaches the lowest temperature?

Of the models on this site, the JOFRA RTC-159 goes lowest, to −100 °C. The JOFRA PTC-125 reaches −90 °C, and the JOFRA RTC-157 and RTC-187 reach −45 °C.

Which calibrators reach thermocouple temperatures above 1,000 °C?

The Additel ADT875-1210 and 878-1210 furnaces (100 to 1210 °C), the JOFRA CTC-1205 (100 to 1205 °C) and the Additel 850 laboratory furnace (100 to 1200 °C).

How do I calibrate sanitary or short, irregular sensors?

Use a liquid bath or a combination unit. The Additel 835 portable bath has a 90 × 90 mm opening. The JOFRA RTC-158, RTC-250 and RTC-168 combine a dry block with a liquid bath, and the RTC-168 is designed for large sanitary flange sensors.

Can a dry well ship with an accredited calibration certificate?

Most temperature calibrators on this site can ship with ISO/IEC 17025 accredited calibration. Specify the range and test points when you request a quote.

Calibration

Most temperature calibrators here can ship with ISO/IEC 17025 accredited calibration. Specify range, points, and whether you need the reference probe on the same certificate.