Additel ADT835 Portable Temperature Calibration Bath

A temperature bath that drifts mid-session does not announce itself. It quietly puts every probe calibrated in that batch out of tolerance, and the problem surfaces later, in a failed audit or a recall of calibration certificates. In regulated production, the stability of the source is what makes the certificate defensible.

The Additel ADT835 is a portable temperature calibration bath built for that job outside the laboratory: on a production floor, in a utility room, or at a customer site, where ambient conditions are not controlled and the calibration still has to hold.

What the ADT835 is

The ADT835 is a portable calibration bath with a 90 by 90 mm well and an accuracy of ±0.1 °C. Unlike a dry-well, a liquid bath surrounds the sensor, so it accommodates probes regardless of type, size, or shape: flanged and sanitary probes, short stem RTDs, and bimetallic thermometers, without custom inserts machined for each geometry.

That matters most in pharmaceuticals, biotechnology, and food processing, where sanitary and non-standard sensors are common and a dry-well insert for every probe geometry is neither practical nor cheap.

Batch calibration and throughput

With a bath depth of 155 mm, the ADT835 holds up to 4 sanitary sensors of 50 mm diameter or up to 40 stem-type sensors of 6.35 mm diameter in a single run. For a plant with a large installed base of temperature sensors, calibrating in batches is the difference between a scheduled maintenance window and a rolling series of shutdowns.

Thermal transitions are fast, which shortens the cycle. The ADT835-150 and ADT835PC-150 heat to 150 °C in 30 minutes and cool to -25 °C in 45 minutes, or -30 °C in 55 minutes. The ADT835-250 and ADT835PC-250 heat to 250 °C in 55 minutes and cool to 100 °C in 30 minutes, or 33 °C in 45 minutes. Non-overshoot control algorithms and predictive temperature modeling reduce stabilization time at each setpoint.

Dual-zone heating: why it holds outside the lab

Field conditions attack stability in ways a laboratory does not: supply voltage fluctuates, airflow moves across the bath, ambient temperature shifts through the day. The ADT835 uses two heaters instead of one. An external heater near the vapor chamber holds a stable baseline, while an internal immersed heater responds to changes as they happen. The result is a bath that keeps its setpoint where a single-heater design would wander.

The PC version: one instrument instead of three

The ADT835PC adds a built-in 3-channel process calibrator: a high-accuracy thermometer, a multimeter, a 24 V loop power supply, a HART communicator, and quick-push electrical connectors. For a technician calibrating a temperature transmitter loop on site, that replaces a bath, a reference thermometer, and a loop calibrator with one case to carry and one setup to verify.

Self-calibration and remote operation

The internal reference thermometer supports automated self-calibration, which removes manual data entry and the transcription errors that come with it. Bluetooth, a Wi-Fi hotspot, and LAN or cloud connectivity allow the bath to be controlled from a PC or mobile device, so a technician can run a long thermal cycle and work in parallel rather than standing by the instrument.

Safety and fluid handling

A stainless steel, corrosion-resistant fluid tank, an overflow management system, visual alerts for fluids above 50 °C, secure drain ports, and a dust-resistant, vibration-tested build. These are the details that decide whether a bath survives a plant environment or becomes a maintenance item itself.

Where it fits

Calibration laboratories and metrology departments, pharmaceutical and biotech production, food and beverage processing, and field service teams calibrating temperature sensors and transmitter loops on site. Typical work includes sanitary probe calibration, RTD and thermocouple verification, batch calibration of an installed sensor base, and temperature transmitter loop calibration with the PC version.

Available Through AV-TEK Consulting

The ADT835 is available through AV-TEK Consulting, with support on selecting the right model: the 150 °C or 250 °C range, the standard version or the PC version with the integrated process calibrator, and the bath fluid suited to your temperature range and sensors. AV-TEK also provides NIST-traceable calibration and repair, so the bath that certifies your sensors stays traceable itself.

View the ADT835 product page, or contact our team at sales@avtekconsulting.com to choose the configuration for your application.

FAQ

Is there a difference between the ADT835 and the ADT835PC?
The ADT835 is the calibration bath. The ADT835PC adds a built-in 3-channel process calibrator with a reference thermometer, multimeter, 24 V loop power supply, and HART communicator, so a single instrument covers both the temperature source and the loop measurement.

Should I choose the 150 °C or the 250 °C version?
It follows your calibration points. The 150 version heats to 150 °C and cools to -25 or -30 °C. The 250 version heats to 250 °C and cools to 100 °C or 33 °C. Share your setpoints and AV-TEK will confirm the right range.

Why use a liquid bath instead of a dry-well?
A bath surrounds the sensor with fluid, so it calibrates probes of different shapes and diameters, including sanitary and flanged sensors, without a machined insert for each geometry. Dry-wells are lighter, but they require inserts matched to the probe.

How many sensors can be calibrated at once?
Up to 4 sanitary sensors of 50 mm diameter, or up to 40 stem-type sensors of 6.35 mm diameter, in a bath 155 mm deep.

Can AV-TEK calibrate the ADT835 itself?
Yes. AV-TEK provides NIST-traceable calibration and repair, so the reference used to certify your sensors remains traceable.

🔗 Ready to Upgrade Your Calibration Equipment?
Discover how the Additel ADT835 Portable Calibration Bath can optimize your calibration workflows, from batch calibration of sanitary sensors to loop calibration on site.
👉 Discover more about ADT835

📞 Want to Learn More or Request a Quote?
Get in touch with our team to explore how the Additel ADT835 can meet your temperature calibration needs. Tell us your calibration points and sensor types, and we will confirm the right configuration for your application.
👉 Contact us at: sales@avtekconsulting.com