Vacuum Breaker is normally-closed valve, designed to prevent the vacuum when tank (vessel) is drained or to prevent siphon in the pipeline. Vacuum Breakers will open to allow air into a pipeline or tank (vessel) preventing siphoning, cavitation, or vacuum, when properly installed and used within the recommended ranges of pressure, temperature, and chemical compatibility.

Plast-O-Matic Vacuum Breakers are designed that can be mounted in any position; however, upright is recommended. For enclosed tank applications, mounting should be at the highest point of the tank.

In the diagram above, a vacuum breaker is positioned on top of the supply tank to prevent implosion when the tank is drained. A second vacuum breaker is shown on a tee to prevent siphon in a vertical drop. This creates a pocket of air in the riser, lateral line, and drop to "break" the suction that would otherwise be created in the drop when the pump is turned off. The blue color indicates liquid in the system when the pump is turned off. When the system is re-started, an air release valve positioned along the high point of the pipeline is necessary to expel the air pocket for safe and efficient operation. Additional air release valves may be necessary at other points, depending upon the size and complexity of the pipeline. Placement of degassing valves (not shown) varies from system to system.

Features/Benefits with Proper Installation:

• Designed to protect enclosed tanks from collapse or structural damage during draining.

• Eliminates siphoning of dangerous fluids.

• Prevents vacuum which can cause damage to sensitive instruments and filters.

• Normally-closed design prevents fugitive emissions from leaving system.

• Insurance against replacement of damaged expensive equipment... avoids critical system downtime.

• Patented diaphragm design assures dependable, repetitive, bubble-tight sealing in VBM and VB; PFA encapsulated spring and special poppet provides identical performance in VBS design.

• For corrosive or ultra-pure liquid applications.