Butterfly Valves for gas 31150 (31050-31250) ... Can be used as an on-off or control valve. Tight to both directions of flow. Read more > 31350 Butterfly valv... Can be used as an on-off or control valve. Tight to both directions of flow. Read more > 31550 Butterfly valv... Can be used as an on-off or control valve. Tight to both directions of flow. Read more >