作用及運用原理：
當管(guan)(guan)內(nei)(nei)開始注水(shui)(shui)(shui)時(shi)，塞(sai)頭(tou)(tou)停(ting)(ting)留在開位(wei)置(zhi)，進行大(da)量排(pai)氣，當空(kong)(kong)氣排(pai)完時(shi)，閥體內(nei)(nei)腔(qiang)積水(shui)(shui)(shui)浮球被浮起(qi)，傳動(dong)塞(sai)頭(tou)(tou)至關閉位(wei)置(zhi)，停(ting)(ting)止大(da)量排(pai)氣；當管(guan)(guan)內(nei)(nei)水(shui)(shui)(shui)正常輸送時(shi)，如 有(you)少量空(kong)(kong)氣聚集在閥內(nei)(nei)至相當程度，閥內(nei)(nei)水(shui)(shui)(shui)位(wei)下(xia)降，浮球隨之下(xia)降，此(ci)時(shi)空(kong)(kong)氣則由小孔排(pai)出。當帛水(shui)(shui)(shui)機停(ting)(ting)止，管(guan)(guan)內(nei)(nei)水(shui)(shui)(shui)流(liu)空(kong)(kong)時(shi)，或遇管(guan)(guan)內(nei)(nei)產(chan)生(sheng)負壓時(shi)，此(ci)時(shi)塞(sai)頭(tou)(tou)開啟， 吸入空(kong)(kong)氣確保管(guan)(guan)線安全(quan)。

SCAR污水復(fu)合(he)式排氣閥為圓桶(tong)式閥體，其(qi)內部主要有(you)不(bu)(bu)銹(xiu)鋼浮球及塞(sai)頭(tou)。污水復(fu)合(he)式排氣閥裝設計于泵(beng)浦(pu)出(chu)水口處或送配水管(guan)線中，用以大量(liang)排除管(guan)道中的集結之(zhi)空氣，以增進水管(guan)及抽水機使(shi)用效率，管(guan)內一旦出(chu)現負壓(ya)(ya)時，此(ci)閥能迅速吸(xi)入空氣，以確保管(guan)線不(bu)(bu)會因負壓(ya)(ya)面被損壞。