1、 Differences and requirements in main operating conditions of butterfly valves

Differences in operating conditions requirements for butterfly valves - serious consequences of misuse
1. Type of medium (medium flowing through the valve)
Minimum requirements for ordinary water/air. Commonly used rubber seats (such as EPDM). The valve body is made of cast iron or ductile iron. Corrosion and leakage: If used in corrosive media such as acid or alkali, the valve body and disc will rapidly corrode, leading to leakage, environmental pollution, or personal injury.
Corrosive chemicals (acids, alkalis, solvents) require the use of corrosion-resistant materials such as stainless steel (304, 316) and Hastelloy for valve bodies, discs, and seats. The valve seat is usually made of PTFE (Teflon) or special rubber. Flammability and explosiveness: When used for gas, standard rubber valve seats will dissolve or expand from solvents, causing seal failure. Gas leakage may lead to explosion.
Food/drugs must use food grade stainless steel (such as 304, 316L) and food grade rubber valve seats. The surface must be smooth, without dead corners, and easy to clean and disinfect. Product contamination: The materials in standard industrial valves may contain toxic substances that contaminate food or drugs, leading to major safety accidents.
Fuel gas/petroleum products require anti-static structures (to prevent static sparks during operation), fire-resistant design (to maintain a certain degree of sealing in the event of a fire), and zero leakage sealing.
2. Temperature (medium temperature)
A standard rubber valve seat (such as NBR) at room temperature (-20 ° C~80 ° C) is sufficient. Sealing failure or fire: At high temperatures, standard rubber valve seats will rapidly age and carbonize, lose elasticity, and cause leakage. At low temperatures, rubber will become brittle and crack. Leakage of high-temperature media can cause fires.
High temperatures (>150 ° C) require metal valve seats or special high-temperature plastics (such as PEEK). The valve body material may also need to be upgraded.
Low temperature (<-20 ° C) requires low-temperature stainless steel and special low-temperature valve seats to prevent material embrittlement.
3. Pressure (medium pressure)
Low pressure (e.g.<1.6 MPa) typically uses centerline butterfly valves. Lightweight structure and low cost. Valve burst or inoperable: Using low-pressure valves in high-pressure pipelines may result in insufficient strength of the valve disc and stem, which may cause the valve to "burst" or completely burst. Using high-pressure valves in low-pressure systems is excessive, increases costs, and requires higher operating torque.
High pressure (e.g.>2.5 MPa) requires the use of metal sealed eccentric butterfly valves (double eccentric or triple eccentric). The valve body and disc are heavier and stronger.
4. Operation requirements (how to control valves)
Manual operation (occasionally on/off) of the handle or worm gear actuator is sufficient. System control loss: Using manual valves in applications that require frequent adjustments or remote control can hinder automation, resulting in slower response times and increased risk of operator errors.
Frequent adjustment/automatic control requires the installation of pneumatic, electric, or hydraulic actuators. Valves should also have appropriate regulating characteristics (such as equal percentage flow characteristics).
2、 A simple analogy

Consider butterfly valves as shoes:

A butterfly valve for regular water is like everyday casual shoes.

Chemical butterfly valves are like acid resistant chemical boots.

Food grade butterfly valves are like sterile surgical shoe covers.

High temperature/high-pressure butterfly valves are like firefighting boots for firefighters.

You don't know how to climb mountains in sandals, nor do you know how to explore the rainforest in leather shoes. Similarly, valves must "wear appropriate shoes"

III、 How to choose butterfly valve correctly?

Follow the steps below to ensure that the valve fully meets the operating conditions:

MVP: What is it? Water, steam, oil, gas, corrosive chemicals or mud?

Determine key parameters (PTC):

Pressure: What is the maximum working pressure of the pipeline?

Temperature: What are the normal and extreme temperatures of the medium?

Size: What is the pipe size (DN)?

Select valve body/internal material: Choose compatible materials (such as cast iron, stainless steel, alloy) based on the medium and temperature.

Choose sealing materials: Select the appropriate valve seat and sealing materials (such as NBR, EPDM, PTFE, metal seals) based on the medium and temperature.

Determine connection type: clamp type, flange type?

Determine the operating method: manual, pneumatic, electric, or hydraulic? Do you need to turn on/off signals or modulation functions?

Conclusion:

Always choose butterfly valves designed specifically for different operating conditions.