Wednesday, September 12, 2012

Butterfly Check Valve How it Works

What is a Butterfly Check Valve?

Butterfly valve is self actuated ,one way ,Non-return valve which allows flow in one direction only.Butterfly check valves have a same disk and seat  arrangement similar as in butterfly control valves. Flow characteristics of butterfly  check valves are similar to the flow characteristics of butterfly valves. Therefore butterfly check valve finds its best pair with butterfly control valve.

Construction and Working Principle of Butterfly Check Valve

The construction of butterfly check valve is such that sufficient space is provided for free movement of disk of butterfly check valve.Valve spacers are also not needed in this type of check valves. The butterfly check valve design is based on a flexible sealing member against the bore of the valve body at an angle of 45o. The short distance the disk must move from full open to full closed reduces  the "slamming" action found in some other types of check valves. 

Butterfly check valve

Because of same flow characteristics ,butterfly check valves have same applications as butterfly control valves. Owing to very quite operation Butterfly check valves have many applications in HVAC (heating ,ventilation and air conditioning ). Simplicity of design also permits their construction in large diameters - up to 72 inches.Seat liners of these valves are also available in many materials which allow HVAC valves manufacturers to provide valves at relatively cheaper rates.Instead of whole body ,seating liners are may be made in corrosion resistant materials .Otherwise we would have expensive valves as in valve constructions with alloys and titanium.

Flexible sealing members of butterfly check valves are available in many materials which has many advantages and disadvantages. Example of flexible materials are Buna-N, Neoprene, Nordel, Hypalon, Viton, Tyon, Urethane, Butyl, Silicone, and TFE as standard, with other materials available on special order. Internals and fasteners are always of the same material as the liner.Butterfly check valve dimensions must match the application.Engineer should work out before invitation of quotations from suppliers as per particular butterfly check valve specification.

Installation of Butterfly Check Valve

Butterfly check valves may be installed horizontally or vertically with the vertical flow either upward or downward.Keep Flow direction from the hinge post end of the this check valve; otherwise, all flow will be stopped.
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