A ball valve uses a rotating ball with a bored passage through the middle - when aligned with the pipe, flow passes straight through with minimal restriction. A butterfly valve uses a rotating disc mounted on a shaft across the flow path.
Both operate on a 90° quarter-turn and can be manual or pneumatically actuated. The choice between them usually comes down to bore size, shut-off tightness and installation weight.
At a glance
| Ball Valve | Butterfly Valve | |
|---|---|---|
| Shut-off | Very tight (Class VI achievable with soft seats) | Good, generally less tight than a full-port ball valve |
| Flow path | Full-port designs offer minimal flow restriction | The disc remains in the flow path even when open, causing some pressure drop |
| Weight & size | Heavier per given bore, especially at larger sizes | Lighter and more compact - the standard choice for larger bores |
| Typical duty | Tight on-off isolation, smaller-to-mid bores | On-off and throttling, larger bores, weight-sensitive installations |
Rule of thumb
For smaller bores (up to roughly 100–150mm) needing bubble-tight shut-off, a ball valve is usually specified. For larger bores, or where valve weight and installed cost matter more than absolute shut-off tightness, a butterfly valve is the more common choice.
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