For the safety and efficiency of a variety of processes, we rely on the performance of butterfly valves. How sound a butterfly valve is depends on the integrity of the seal.
The valve must be able to withstand the particular working conditions of any given process. Such conditions involve elements that are corrosive, extremely hot, or high pressure. The seal must resist wear and tear with repetitive opening and closing.
The integrity of the seal depends on the butterfly valve seat. That’s why you must choose one that is appropriate for the conditions of the process. With this guide, you will learn which butterfly valve seat is suited for which process.
What is a Seat On a Valve?
Essentially, a valve seat is where the moving component of a valve rests when in the closed position. In butterfly valve applications, the disc rests securely on the seat to close and seal the valve. Seats are designed to keep the seal intact despite the thermal, friction, and impact stresses of a process.
Selecting a Valve Seat Type
We have different types of butterfly valves for various applications. The type of butterfly valve seal used depends on the application conditions: temperature, pressure, and type of media. For more information on what pressure and temperature a valve can tolerate, refer to the specs published by the manufacturer.
BUNA-N (B)
BUNA-N is another name for nitrile which is a synthetic rubber copolymer of acrylonitrile (ACN) and butadiene. Because of its abrasion resistance, tensile strength, and low compression set, this rubber is a widely used elastomer in the seal industry.
BUNA-N is highly resistant to hydraulic fluids, water, alcohols, acids, petroleum-based oils, fuels, silicone greases, etc. However, what makes it strong also makes it inflexible. BUNA temperature rating is 0°F to 180°F and is heat resistant up to 225°F.
This material is used in some automotive applications. However, BUNA-N is not suitable for applications that involve acetones, ketones, chlorinated hydrocarbons, nitro hydrocarbons, or ozone.
