This instrument is side mounted, directly to the flange on the side of oil and gas separators, vaccum towers, fractionating/distillation columns, liquid containers where a float operating inside of the tower can be used. However this instrument is not recommended in turbulent and foaming fluids. These are widely used in industries like: Refineries, Gasoline Plants, Industrial Paints, Oil and Gas Separators or any other similer installations. it consists of a Ball type Float, Float rod, Collar, Shaft & Gland housing. Pneumatic Relay is made of Brass which is weather proof and therefore enables the instrument suitable for outdoor application and even in moist conditions.

The position of ball float is determinded by the fluid level variation that actuates the rod through a system of levers. The instrument is based on the Archimedes Principle. Any increase in level raises the float up; it is also helped by counter weight in its upward movement. The mechanical link operates the plunger of pneumatic relay and it changes the output pressure which finally operates the control valve. The maximum span of the plug turn is 50° which is approximately a range of 300 mm in terms of level. The pneumatic relay operates at 1.1 to 2.5Kg/cm² of purified, dry natural gas or air.