The BK24A is a mercury vapour ignitron designed for resistance welding control.
This AEI branded product has grey paint over a black painted body. The BTH branded version was probably made in the same facility in Rugby.
The cathode end with steel connecting bar. The small connection to the right is for the igniter circuit.
The cathode on the right and anode on the left. The multi-stranded anode wire has been cut just above the glass cylinder. The thermostatic controls are under the plastic cap.
The anode end. The evacuation pip is protected by the bracket seen on the right.
The wide metal tube envelope is 100 mm in diameter, and the water jacket is 236 mm tall.
Reference: Data-sheet. Type BK24A was first introduced in 1959. See also1959 adverts.
