Spirax Sarco VB21 kinds of small general-breaking vacuum, mainly for condensing vapor (steam) and liquid systems. 
For, when the steam system pressure below atmospheric pressure, the vacuum pipe break. 
 
· Protect equipment from damage to the vacuum 
· At the same time, can effectively exclude pipes and heat exchanger condensate. 
Installation 
VB21 air valve must be installed in a vertical position, the system connector located on the bottom of the vacuum break valve. As for the steam system, emptying valve must be installed on the highest point of the system, and to prevent condensation of water valve is not invaded.
VB21種小型通用破真空器，主要用于冷凝蒸汽（蒸汽）和液體系統。
用于在蒸汽系統壓力低于大氣壓力時，破除管道真空。

· 保護設備不受真空損壞
· 同時，可有效排除管道和換熱器中的冷凝水。
安裝
VB21空閥必須安裝于垂直位置，系統連接口位于破真空閥的底部。如用于蒸汽系統，排空閥必須安裝于系統的zui高處，與防止閥被冷凝水侵沒。