Spirax-Sarco valve mechanism for B4 series bucket steam trap. Spirax-Sarco valve mechanism less bucket is the device that allows the condensate and air to drain from the trap. The mechanism is a lever and seat operation, it is held in place by screwing the seat into the outlet port within the trap. With the inverted bucket attached to this mechanism, the steam pressure within the bucket keeps the lever up in turn keeping the seat closed when steam is present. When the steam cools and turns to a liquid state (condensate), the trap fills with condensate causing the bucket to drop and this opens the seat to allow the condensate and air to drain.斯派莎克直接作用式減壓閥BRV73閥門機制B4系列吊桶式疏水閥。 斯派莎克直接作用式減壓閥BRV73機構少鏟斗裝置，使冷凝水和空氣從陷阱排出。該機構是一個杠桿和座椅的操作，它在適當的位置通過螺紋連接在座椅進入出口端口陷阱內舉行。與連接到這個機制倒斗，斗內的蒸汽壓力保持桿，反過來保持座位關閉時蒸汽存在。當蒸汽冷卻并變成液體狀態（冷凝），陷阱充滿冷凝水造成杯水車薪，這將打開座椅，讓冷凝水和空氣排出。