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种小型通用破真空器，主要用于冷凝蒸汽（蒸汽）和液体系统。
用于在蒸汽系统压力低于大气压力时，破除管道真空。

· 保护设备不受真空损坏
· 同时，可有效排除管道和换热器中的冷凝水。
安装
VB21空阀必须安装于垂直位置，系统连接口位于破真空阀的底部。如用于蒸汽系统，排空阀必须安装于系统的zui高处，与防止阀被冷凝水侵没。