Valavu ya butterfly, yomwe imadziwikanso kuti flap valve, ndi mtundu wa valve yowongolera yomwe imagwiritsidwa ntchito kwambiri m'mafakitale osiyanasiyana powongolera kutuluka kwamadzi. Zili ndi zigawo zingapo zofunika, kuphatikizapo thupi la valve, tsinde la valve, mbale ya butterfly, ndi mphete yosindikiza. Zigawozi zimagwirira ntchito limodzi kuti zitsimikizire kuti valve ikugwira ntchito moyenera komanso molondola.