The Isotech Model 875 Fluidised Calibration Bath is a high-precision solution for thermometer calibration across a broad temperature range. It outperforms traditional salt baths by offering safer operation, excellent thermal stability, and reduced maintenance.
Developed over more than 20 years of research into powder flow, fluidisation, and filtration, the 875 is trusted by national laboratories, ISO 17025 accredited facilities, and demanding industrial users. It is particularly wellsuited for the temperature calibration of long-stem MIMS thermocouples.

Designed to deliver consistent and repeatable results, the 875 excels in comparison calibration. Its fluidised powder medium provides exceptional temperature uniformity and thermal contact—without the risks associated with corrosive salt media.

A key advantage of the Model 875 is its deep immersion capability of up to 475 mm—significantly more than dry block calibrators. This reduces stem conduction errors which is critical for high-accuracy calibration. In our own ISO 17025 accredited laboratory, we use the 875 for comparison calibration of Platinum Resistance thermometers from 300°C to 700°C, achieving uncertainties as low as ±0.020°C at 300°C and ±0.035°C at 660°C.

The system uses high-purity aluminium oxide powder, fluidised by compressed air passing through a porous base plate. This creates a uniform, stable medium with excellent heat transfer properties. Unlike many fluidised baths that rely on metal blocks or collapsing the bed to improve stability, the 875 delivers full thermal performance with the powder in flow.

• Fluidised Furnace Data Sheet
• The Best Comparison Calibration Equipment