 Bellow akara ụwa valvụ, ndị dị oké mkpa akụkụ nke nke-metal nokpuru, akpaka mpịakọta ịgbado ọkụ ala nke bellow na azuokokoosisi akụrụngwa, akpaka mpịakọta ịgbado ọkụ nelu bellow na ejikọta efere, nke bụ metal mgbochi betweeen ọmụmụ na ikuku, hụ esiwe na efu-ehi ehi. 