Two basic types of valves are offered –Motorised and gravity operated. Gravity operated valves close by the action of counter weights whereas motorised valves can have counter weights or spring to impart the closing force. Valves can be made for material temperature as high as 1000°C.The required refractory lining in casing remains in customer’s scope. Flaps or cones are self-aligning type so that a leakproof seating of flap/cone on seat is achieved. Larger valves usually have 2 –flaps per stage whereas smaller valves have a single flap per stage. However large size valve with single flap is also possible.