Butterfly valve (lenticular disc $s/D=0.26$)
<img src="https://eng-calculations.com/SVG/Hydraulic_engineering/Valves/Butterfly valve (lenticular disc (and36)s(and47)D(and61)0(and46)26(and36)).svg" alt="Butterfly_valve_(lenticular_disc_(and36)s(and47)D(and61)0(and46)26(and36))" title="Butterfly_valve_(lenticular_disc_(and36)s(and47)D(and61)0(and46)26(and36))">
https://eng-calculations.com/SVG/Hydraulic_engineering/Valves/Butterfly valve (lenticular disc (and36)s(and47)D(and61)0(and46)26(and36)).svg