Temperature range 200degC to 1100degC
  Working volume diameter x depth = 203 x 203mm

The BFS is designed for applications requiring a constant high temperature source for calibration. The BFS has a hinged lid and a cylindrical bath 218mm in diameter and 254mm deep. Substantial fire brick insulation is incorporated within the outer container and the lid.

Standard equipment includes a separate air supply control unit which incorporates two flowmeters for monitoring the air supply and a charge of fluidising medium (aluminium oxide) and air diffuser (zirconium oxide).

The inner container of the BFS is filled with two layers of fine granular particles. The lower layer (zirconium oxide) is denser than the upper layer (aluminium oxide) and does not fluidise but instead acts as a heat insulator. The inner container of the BFS is divided into inner and outer fluidised sections. Each area has a separate air supply which must be oil, water and dust free.

The air supply may be monitored on flowmeters in the air flow unit. Air supplies are adjustable to obtain uniform fluidisation in both sections of the bath. Heaters are mounted in firebrick insulation between the inner and outer container; heat is radiated inwards to the fluidised bath.

An air extraction tube is located in a horizontal position in the side of the bath just below the hinge on the lid. When the lid is closed, dust created by the bath's operation can be withdrawn by connection to an extraction duct or fan. The dust can also be trapped in a small tank of water.