| Municipal water supply | Resilient-seated concentric butterfly valve | PN10 or PN16; Class 150 in some systems | Approximately 0°C to 80°C, depending on the liner | Ductile iron or carbon steel body; ductile iron, stainless steel, or coated steel disc | EPDM is commonly selected for treated water and potable-water service | Corrosion protection, low operating torque, bidirectional shutoff, and suitable drinking-water compliance where required | ISO 5208, EN 593, AWWA C504, and applicable potable-water requirements |
| Wastewater and sewage | Resilient-seated or eccentric butterfly valve | Commonly PN10 or PN16 | Approximately 0°C to 80°C | Ductile iron or coated carbon steel body; stainless steel or coated ductile iron disc | EPDM for general wastewater; special elastomers may be required for oils or aggressive chemicals | Resistance to suspended solids, abrasion, corrosion, and biological wastewater conditions | ISO 5208, EN 593, EN 1074-2, and project-specific leakage requirements |
| HVAC chilled-water systems | Wafer or lug-type resilient-seated butterfly valve | PN10, PN16, or Class 150 | Typically 0°C to 40°C for chilled water | Ductile iron or carbon steel body; stainless steel or coated ductile iron disc | EPDM is widely used for water; insulation compatibility and condensation control are important | Low pressure drop, compact installation, reliable shutoff, and actuator sizing for differential pressure | ISO 5208, EN 593, MSS SP-67, and applicable HVAC specifications |
| Cooling-water intake and seawater | Eccentric butterfly valve with enhanced corrosion protection | Often PN10 or PN16; higher ratings may be specified by the project | Approximately 0°C to 50°C for many cooling-water services | Coated carbon steel, ductile iron, duplex stainless steel, or other corrosion-resistant alloys | EPDM or other seawater-compatible elastomers; verify resistance to chlorides and biofouling chemicals | Chloride resistance, anti-corrosion coating, shaft protection, and suitability for frequent operation | ISO 5208, EN 593, ISO 12944 coating requirements, and project marine specifications |
| Steam and hot-water service | High-performance double-offset butterfly valve | Class 150 or Class 300; select according to design pressure and temperature | Temperature may exceed 150°C; the exact limit depends on seat and body materials | Carbon steel or stainless steel body; stainless steel disc is common | Metal or graphite-based seats may be required; standard EPDM is not suitable for steam | Temperature-pressure rating, thermal cycling, fire safety, torque margin, and leakage class | API 609, ISO 5208, EN 593, and applicable fire-safe requirements |
| Oil, fuel, and hydrocarbon service | High-performance or triple-offset butterfly valve | Class 150, Class 300, or higher according to the piping design | Commonly -20°C to 180°C, subject to the selected materials | Carbon steel, stainless steel, or alloy steel body and disc | Nitrile, PTFE, graphite, or metal seats may be selected for hydrocarbon compatibility | Fire-safe construction, fugitive-emission control, anti-static continuity, and chemical compatibility | API 609, API 607 or ISO 10497, ISO 15848, and ISO 5208 |
| Corrosive chemical processing | Lined butterfly valve or alloy-bodied eccentric valve | Typically PN10 to PN16 or Class 150, depending on the chemical system | Usually 0°C to 120°C for lined designs; verify the liner rating | Lined carbon steel, stainless steel, or corrosion-resistant alloy construction | PTFE, PFA, EPDM, FKM, or other elastomers must be matched to the exact chemical concentration | Chemical compatibility, permeation resistance, abrasion resistance, and documented material certificates | ISO 5208, EN 593, API 609 where applicable, and the chemical compatibility specification |
| Compressed air and general gas | Resilient-seated or high-performance butterfly valve | PN10, PN16, Class 150, or as specified by the gas system | Approximately -20°C to 80°C for many general-service systems | Aluminum, ductile iron, carbon steel, or stainless steel according to pressure and corrosion conditions | NBR, EPDM, FKM, or PTFE selected according to gas composition and temperature | Low leakage, correct flow direction, actuator fail position, and compatibility with lubricants or condensate | ISO 5208, EN 593, API 609, and applicable gas-system safety requirements |