Butterfly Valve
A butterfly valve is a quarter-turn on/off isolation valve where a disc rotates 90° in the bore to open or close flow. It is the low-cost choice for large-bore line isolation and tank outlets.
What is a Butterfly Valve
Butterfly valves use a central disc on a shaft; turning the shaft 90° moves the disc parallel (open) or perpendicular (closed) to flow. Soft-sealed designs use a resilient PTFE or EPDM seat for tight shut-off; triple-eccentric designs add a metal seat for high-temperature, zero-leakage duty.
Materials & standards
- 316L stainless steel body for hygienic and industrial duty
- PTFE or PFA seat/liner for aggressive chemicals
- EPDM or FKM elastomer seals by fluid
- ANSI / DIN / JIS flange faces
- 3A hygienic version for sanitary lines
Typical applications
- Large-bore line isolation and tank outlets
- HVAC and water treatment
- Pulp, mining and general process
- Hygienic 3A duty for food, dairy and beverage (soft-sealed)
- Corrosive chemical service (PFA/PTFE lined)
Butterfly Valve at a glance
| Sealing | Tight with resilient seat; bubble-tight in triple-eccentric metal design |
|---|---|
| Cleanability | Good; full-bore, low dead leg in hygienic versions |
| Relative cost | Lowest for large bore |
| Best use | Large-bore isolation where weight and cost matter more than bubble-tight shut-off |
Frequently asked questions
When is a butterfly valve the right choice?
For large-bore isolation and tank outlets where low weight and low cost matter more than bubble-tight shut-off. For small-bore tight isolation, a ball valve is usually better.
What is a triple-eccentric butterfly valve?
A metal-seated design with three offsets that eliminates seat rubbing and gives zero-leakage, high-temperature performance for steam, heat-transfer and fire-safe duty.
Which liner resists aggressive chemicals?
A PFA or PTFE lined butterfly valve isolates the metal body from the fluid and is specified for aggressive or pure-chemical service.
Last updated: 2026-10-08
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