Improvements in or relating to metal strip treatment apparatus

878,044. Cleaning metals. ALUMINIUM LABORATORIES Ltd. March 10, 1960 [March 23, 1959], No. 10030/59. Class 82(2) Apparatus for the surface treatment of metal strip or sheet such as aluminium comprises at least one enclosed reaction chamber 6 located over and communicating with a holding tank 8, suction means 9 connected to the chamber 6 to maintain the liquid level in 6 at a higher level than the level in the tank 8 and above the level of the strip which passes through the chamber 6, and sealing flaps 10 and 11 in opposite walls of the chamber. The strip from coil 2 is passed via pinch rolls 4 in a straight path through the chamber 6 by means of a chain conveyer 7 and a circulating pump agitates the liquid in the chamber 6 and mixes it with the liquid content of tank 8 in which a thermostatically controlled heater may be installed. The flexible entry and exit sealing flaps 10 and 11 act as scrapers and minimize liquid carry over from one chamber to the other while the suction fan 9 also limits liquid carry over as well as maintaining the liquid level and ensuring fume extraction. In a further embodiment (Fig. 3) the chain conveyer is replaced by a pair of chains 17 which follow parallel paths through the chamber 6 and turn about sprocket wheels 18. The strip or sheet is secured to a bar 19 and sprockets 20 engage with the chains 17 for movement through the reaction chambers.