The instrument consists of a stainless steel case in which is mounted the electrical heater, liquid bath and glass test cup. The button-operated, electrically driven sweep arm can use either mains gas or LPG from the optional Portable Gas Tank (13667-0). At the rear of the raised panel is a gas inlet block, comprising a 10 mm diameter nozzle and a pinch valve for adjusting the size of the test flame. A test flame size bead is mounted on the top of the liquid bath.