Carbon Monoxide Detector – National Coal Board.
This detector is the T. C. O. II type from the Scientific Department of the National Coal Board North Western Division.
Made from iron, glass and plastic. Size 10″ x 9″ x 6″ inches.
The detector has a hinged from compartment which is locked from the back with a cylinder lock. This piece is numbered 2 with its original key.
The carbon monoxide detection range is in three stages – 1, 2, and 3. Range 1 is 0-03%. Range 2 is 0-0.1% and Range 3 is 0-0.3%.