High-accuracy bath with fluidised media for temperature values from –100°С to +1100

High-accuracy bath with fluidised media for temperature values from –100°С to +1100

Bath with dry fluidised (pseudoliquid) media is recommended by international regulatory documents, namely by ASTM standard Е 220-02 "Standard test methods for thermocouple calibration by comparison" as a calibration instrument within temperature range from –70 to 980°С. These instruments are rather widely used abroad. In Russian fluidised bath is almost an unknown tool. It is not mentioned as a calibration instrument in any existing standard.
Techne company is the pioneer in fluidised bath technology development. The company manufactures baths operating at temperature from –100°C to 1100°C.
Fine aluminium oxide is used in bath as a working fluidised medium. Gas flow passes through porous distribution plate and is blown through aluminium oxide layer. As a result gas flow falls into separate particles mixed in gas flow, so the medium looks like boiling liquid. Like liquid, fluidised medium has fluidity and high thermal conductivity. When heated, medium particles quickly distribute heat within the bath and heat up objects immersed in the bath. Medium temperature quickly becomes stable at any set level (not more than 90 minutes for maximum). The medium has no melting or boiling points within operating temperature range, thus there are no problems with setting-up, as in salt bath, or with vapour, as in liquid baths.

Aluminium oxide circulation provides thermal uniformity

SBL-2D                    SBL-2





TESEY company is the official Techne dealer in Russia. We offer several series of fluidised baths.

SBL series baths

These are compact and relatively low-cost baths with thermal stability ±1°С, that can be used for measuring instrument calibration or material thermal processing. Temperature range is 50–350°С for SBL-1 and 50–600°С for SBL-2. There are several modifications of SBL-2 bath, immersion depth 140 and 350 mm. If the bath is equipped with additional TC-8D PID-regulator, it can support stable temperature within ±0.3°С.

FB-08 series baths

FB-08 bath can be used in several metrological and research applications. Bath specification corresponds to requirements of GOST R 8.624-2007, GOST 8.338-2002, GOST 8.611 to furnaces. Temperature adjustment range 50–700°С. Bath specification is given in the table 1. According to our research data of FB-08 bath thermal field, at temperature up to 600°С inclusively, radial gradient does not exceed 0.07°С/cm, axial gradient does not exceed 0.01°С/cm.

Specified bath characteristics allow to calibrate 3-category reference resistance thermometer RRT-100 by direct comparison with 2-category resistance thermometer-10. Calculation results show that calibration expanded uncertainty at aluminium freezing temperature level (660°С) equals to 0.14°С under required RRT-10 confidence error equal to 0.15°С.

Bath characteristics allow to use the bath for calibration points setting for indium, stannum, zinc, and aluminium. It is almost impossible to replace the bath, if you determine thermoelectric effect in resistance thermometers or study thermoelectric non-uniformity in thermocouples.

According to GOST 8.338 requirements, thermocouples with immersed part longer than 250 mm are subject to calibration. Such requirement comes from calibration furnace structure. Methodical guidelines MI 70.32-87 (not valid at present) used for calibration of thermocouples with immersion length up to 250 mm. These guidelines allowed to calibrate short sensors up to temperature 700°С by means of stannous bath. This method was not gaining wide ground as there is no series-produced stannous baths, and it is difficult to work with them. With the use of FB-08 bath, minimum immersion length reduces from 250 to 50 mm (for 3-5 mm diameter thermocouple) on condition that temperature of adapter sleeve (terminal head) does not exceed 100°С. TESEY's specialists developed calibration method for thermocouples less than 250 mm long, in which fluidised bath FB-08 is used. The method is approved and registered in compliance with the established procedure under number MI 3090-2007.

FB-08LT bath modification is designed for temperature range –100°C to 200°C, if liquid nitrogen is connected to the bath.

FB-08C modification is adjusted within the range 50°C to 700°С. This bath is designed for automatic measuring tool calibration at set temperature levels. This unit is characterized by automatic mode of air flow stop for a short time to obtain stable temperature not less than 0.01°С/min.

BFS bath is a high-temperature bath with temperature range 200°C to 1100°C. Bath performance specification is given in the table 1.

Fluidised bath has several doubtless advantages both over oil bath, dry-block calibrator and tube furnace. In our opinion, fluidised bath is the best unit for temperature measurement and maintenance during calibration, verification, standardization or temperature conditioning within temperature range –100°C to 1100°C.

Performance specifications of fluidised bath





Adjustment range,




Temperature stability

± 0.5°С

± 0.3°С (0.08°С/min)

±1°С (±0.3°С for

Temperature uniformity
in operating volume

at 350°С ± 0.5°С

at 200°С ± 0.2°С (0.02°С/cm)

at 600°С ± 2.0°С

at 400°С ± 0.4°С (0.04°С/cm)

at 1000°С ± 3.5°С

at 600°С ± 0.8°С (0.08°С/cm)

Nominal power
of heaters, kW




Air pressure,
kPa (psi)

47 (7)

420 (60)

21 (3)

Maximum flow rate,




Weight of medium:




aluminium oxide

17 kg

16 kg

16 kg

zirconium oxide

8 kg

Working volume:
Diameter x depth, mm

82.5 x 203

150 x 300

228 x 140

Inner dimensions:
Diameter x depth, mm

218 x 260

165 x 385

Outer dimensions:
L x W x H, mm

686 x 686 x 876

770 x 515 x 600

385 x 470 (D x H)

Delivery terms

Fluidised bath FB-08 is supplied together with the tools type approval certificate valid in the Russian Federation.