Iyo indekisi yekuita yemhepo sefa inonyanya kureva guruva rinobvisa kushanda zvakanaka, kuramba, uye guruva rinobata simba.Kubvisa guruva kushanda zvakanaka kunogona kuverengerwa maererano nenzira inotevera:
Kubvisa guruva kushanda zvakanaka=(G2/G1)×100%
G1: Avhareji yehuruva huwandu musefa (g/h)
G2: Avhareji yehuruva huwandu hunogona kusefa (g/h)
Iyo huruva inobvisa kunyatsoshanda zvakare zvinoenderana nehukuru hwechikamu.Resistance zvinoreva kudzvanyirira kwakasiyana.Pachimiro chekuve nechokwadi chekuti sefa yakatsetseka, iyo diki yekusiyanisa kudzvanywa ichave iri nani.Kuramba kunowedzera kunozopedzisira kwaguma nekushandiswa kukuru kwesimba.Kunyanya kupikisa kunopa kuzunguzika kwemhepo compressor.Naizvozvo, iwe unofanirwa kutsiva iyo sefa chinhu kana iyo yekusefa kuramba yasvika kana iri padyo neinobvumidzwa vacuum pressure.Pamusoro pezvo, guruva rinobata simba rinoreva avhareji yakaunganidzwa guruva pachikamu cheyuniti.Uye chikamu chayo chiri g/m2.