Isotech 4857 Gemini Large‑Volume Dry Block Calibrator

The Isotech Gemini 4857 is designed for applications where a standard dry block simply does not offer enough space. Some sensors are large, heavy‑duty or housed in industrial enclosures that do not fit into compact blocks. Other situations require the simultaneous calibration of multiple probes or even a complete measurement loop. The Gemini is built for exactly these challenges: a large, deep and exceptionally stable dry block calibrator capable of handling sensors that fall outside the scope of traditional block systems.

Large block capacity for oversized and complex sensors

At the core of the Gemini is its generous 64 × 160 mm block, providing ample room for large‑diameter probes and multiple sensors at once. The increased thermal mass heats and cools more slowly than smaller models such as the Jupiter or Hyperion, but it delivers a remarkably calm and uniform temperature field. For laboratories that prioritise stability and capacity over sheer speed, this is a significant advantage.

Three versions to match different workflows

The Gemini is available in three controller configurations, each tailored to a specific working style.

Basic
The Basic version provides a clear display of setpoint and block temperature, making it ideal for straightforward and reliable dry‑block calibrations.

Site
The Site version adds an independent temperature indicator for a reference probe. This eliminates gradient and loading errors and is particularly useful for audits, fieldwork and comparison‑based calibrations.

Advanced
The Advanced version is designed for laboratories that require maximum capability. With a full‑colour display, automatic temperature cycling, secure data logging, a built‑in web server and multiple inputs for reference and test sensors, it is ideal for regulated industries such as aerospace, automotive and life sciences.

Two temperature ranges: Gemini 550 and Gemini 700

The Gemini is available in two operating ranges:

• > Gemini 550: 35 °C to 550 °C
• > Gemini 700: 50 °C to 700 °C

Both models offer impressive stability, typically between ±0.01 °C and ±0.03 °C, depending on temperature and controller. Uniformity meets the requirements of EURAMET cg‑13, making the Gemini suitable for demanding metrological applications.

LRI version with removable inserts

Alongside the fixed‑block versions, the LRI (Large Removable Insert) model allows blocks to be swapped or custom‑drilled. This is ideal for sensors with unusual diameters or geometries. While sleeves always introduce additional thermal gradients, a custom‑drilled LRI block provides a much cleaner thermal interface.

Thermal performance and heat/cool behaviour

Despite its size, the Gemini performs surprisingly quickly. It heats from 30 to 550 °C in around 35 minutes, and cools from 550 to 275 °C in a similar timeframe. The LRI version takes slightly longer but offers unmatched flexibility. The unit is robust, compact and portable enough for both laboratory and on‑site use.

Accessories and options

A wide range of accessories is available, including sleeves, custom inserts, a current loop interface for 4–20 mA transmitters, standard PRTs and Type N thermocouples, and rugged wheeled carrying cases. UKAS calibration is available for both block temperature and reference inputs.

The Isotech Gemini 4857 is far more than a standard dry block. It is a large‑volume, highly stable and exceptionally versatile calibration platform for sensors that exceed the limits of conventional systems. It is the ideal choice for laboratories that need to combine capacity, accuracy and flexibility in a single, dependable instrument.