Butterfly Valves: Here’s What You Should Know
The simplicity of butterfly valves, and their typically low maintenance costs that result, are just one of the advantages that they have over other types of valves, such as ball, globe, plug and gate. Butterfly valves also offer weight, space and cost savings that are difficult to achieve with other valve types.
What are they?
Damper valves are used for air flow control and diversion applications. A butterfly valve is a damper that has only one wafer to control airflow. A louvered damper has multiple wafers that open/close to control airflow. All butterfly valves are damper valves, but not all damper valves are butterfly valves. A louvered damper valve is not a butterfly valve.
Confused? Don’t be.
A butterfly valve is a quick opening, rotational motion valve that uses a metal, circular disc (vane) to start, stop or regulate flow in a pipe. Typically, a simple 90° rotation of the valves handle either opens or completely closes the valve as the vane seals itself against the seats in the valve housing. These seals are either made with a metal to metal connection or to a softer, elastomeric material.
Butterfly valves are especially well-suited for handling of large, low pressure flows of liquids or gases. They are also often used to control the flow liquids that may also contain a certain amount of suspended solids, called a slurry. Based on the same principles of a pipe damper, butterfly valves provide excellent on/off flow control.
Custom valve design
Streamline Industries has been manufacturing custom butterfly valves of all sizes for more than 20 years. Designed specifically to meet the needs of our customers, our shop can produce valves made from a variety of materials and fit flange connections for pipe ranging from 6″ to 60″.
Not only can our skilled and experienced personnel manufacture valves built to meet the exact specifications of our customers, we are also called upon to develop custom designs and even reproduce obsolete “one off” components. Our manufacturing process enables us to fabricate new valves to replace failed, existing equipment without requiring any modifications to the existing piping.
For our clients in the chemical, refining, mining, and agriculture industries, our experience and expertise in mitigating vibration, and providing on-site machining has also become a valuable resource. Providing vital repairs to industrial machinery quickly and effectively.
Avoiding problems with butterfly valves
The majority of issues that we encounter with butterfly valves in the field are caused by improper installation, rather than the piece of equipment itself. Carefully laying out the system, including all pipework and installation valve itself can greatly reduce maintenance issues down the road.
One reason that a butterfly valve will fail has to do with the seating found within it. Since a seal is created by seating extending over both faces of the valve, no additional gaskets are required. However, if the extended seat material is compressed during installation, the seat will eventually wear unevenly, causing the seal to fail much sooner than it was designed to.
Also, unlike other valve types, a butterfly valve’s disc extends beyond the face of the valve body and may come to rest at the same angle as the opening when installed between flanges. Therefore, it’s critical to make sure that disc turns freely as it enters the flanges and piping before installation occurs.
Other important valve considerations
Butterfly valves are usually installed with the stem located in the vertical position and with the actuator mounted vertically directly above it. Whenever possible butterfly valves should be installed at a minimum of six pipe diameters from other line elements, such as elbows, pumps and other valves. If this is not attainable, valves should be located as far apart from these elements as possible.
Lastly, if a butterfly valve is connected to a check valve, be sure to maintain enough space between the two so that the movement of the butterfly valve disc does not impede the functioning of the adjacent equipment.
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