Does ANYONE knows how to size a vacuum breakers in pipelines?

Replies

• 

  Rizvi

  I am also looking how to size a vacuum breakers in pipes. I would highly appreciate if some one can help us on this issue
  Thanks
  Rizvi
• 

  gohm

  Can you give a bit more detail about slurry lines? not familar with those, the vacuum breakers I know of are sized by pipe size, npt.
• 

  Ernesha

  Vacuum Breakers
  
  Compact, Self-Closing Vacuum Breakers Protect Tanks and Piping Systems Against Hazards, Damage and Financial Losses Caused by Vacuum!
  
  
  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 and avoids critical system downtime.
  • Patented diaphragm design assures dependable, repetitive, bubble-tight sealing in VBM and VB; PFA encapsulated spring and special poppet provide identical performance in VBS design.
  • For corrosive or ultra-pure liquid applications.
  • Sizes: ½", ¾", 1", 1½", 2" and 3".

  Materials of Construction:
  
  Series VBM Vacuum Breakers are molded of Geon® type 1, grade 1, PVC (Polyvinyl Chloride), Corzan® CPVC, Glass-filled Polypropylene and Kynar® PVDF in pipe connection sizes ½", ¾" and 1".
  A machined version, Series VB is available in PTFE in sizes ¾" and 1".
  Diaphragms are of EPDM or FKM (Viton). Fasteners are not used on Series VBM. Fasteners used on PTFE Series VB are stainless steel and are NOT in contact with process liquid.
  
  VBS Vacuum Breakers are available in Geon® PVC, Natural Polypropylene, Corzan® CPVC and Kynar® PVDF in sizes 1½", 2", and 3". Standard dust caps on PVDF models are natural polypropylene; PVDF dust cap is optional.
  Series VBS Seals are EPDM or FKM. No fasteners are used on Series VBS. The self-guided spring is completely encapsulated (not coated) with PFA. The encapsulation is not "adehered" to the spring. It flexes independently of the spring and does not crack or flake the way coatings can. This encapsulation has been tested for over 1,000,000 cycles in laboratory conditions with no ill effects.
  
  Connection Types:
  
  Threaded connections are standard on all models. Socket end connectors are available on all sizes and materials except PTFE VB. Outlet connection is shipped with standard dust cap. Cap is removable for applications where pipe connection is desired due to location, potential hazard, etc. The outlet connection is identical to the connection on the system side of the valve. If your application requires an unusual connection, custom material or configuration, please contact our Technical Team at 973-256-3000.
  Design:
  
  The Plast-O-Matic Series VB and VBM Vacuum Breakers have only one moving part - the patented self-sealing diaphragm, and this provides both design simplicity and maximum operating dependability. This normally-closed design seals in the identical location every time producing a very dependable, long-life seal.
  
  Series VBS Vacuum Breakers feature a corrosion resistant PFA encapsulated spring which acts on a poppet seal that neither sticks nor chatters. Maximum working pressure is 100 PSI @ 75°F (6,9 bar @ 24°C).
  Operation and Installation:
  
  Plast-O-Matic Vacuum Breakers feature a patented, normally-closed, design 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.
  
  
  
  
  
  Uses of Vacuum Breakers in a Typical Piping System
  
  
  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. Performance:
  
  These Vacuum Breakers will begin to break a vacuum at approximately 2 inches of mercury (1.0 PSI or 0,07 Bar negative pressure). Full vacuum is 29 inches of mercury. For applications either draining or pumping from enclosed tanks, the tanks must be able to withstand much more than 2 inches of mercury of vacuum, as illustrated in the chart below. The chart is based upon a 3.5 times safety factor, and it clearly shows that as the rate of liquid flow leaving the tank increases, the resulting vacuum in the tank also increases.
  
  Explanation of Graph:

  1. The above graph relates liquid flow leaving an enclosed tank to the resulting vacuum created in the tank as air is entering the tank through the Vacuum Breakers. A safety factor of 3.5 times is used in constructing the graph.
  2. To use the graph determine the rate of flow when draining the tank and from that location on the vertical axis read across to the graph of the proper vacuum breaker size. At this intersection of the graph read down to the horizontal axis and determine the vacuum for the tank. This is the recommended vacuum rating of the tank which must be checked with the tank manufacturer's rating to be sure the tank is strong enough.

  Anti-Siphon Applications:
  
  For these applications the Vacuum Breakers must be installed in a "U-bend" at least 30 inches (2½ feet or 76 cm) above the highest liquid level. Depending on the safety factor desired for Anti-Siphoning this height would become 60 inches (5 feet or 152 cm) at 2 times safety factor which is recommended by Plast-O-Matic.
  Use Caution in Dangerous Applications:
  
  In the event a diaphragm failure could cause spraying of a dangerous liquid onto nearby equipment or personnel, or simply into the atmosphere where breathing the vapors would be dangerous, it is strongly advised to use a Plast-O-Matic #-Link-Snipped-# in lieu of the Vacuum Breaker, and pipe the vent or inlet side of the check valve to a safe remote location. The Check Valve will have the same flow capabilities of the Vacuum Breaker, and contains the same design.
  Elimination of Vacuum in a System:
  
  To prevent instrument or system malfunction, the same considerations are involved as in the tank application. The vacuum breaker should be installed at the highest location in the system. Plast-O-Matic Vacuum Breakers can be mounted in any position since they are self-sealing and do not rely on gravity to operate; however, upright is preferred. #-Link-Snipped-#
  
  
  
  Dimensions:
  
  Series VBM - Molded Models: PVC, GPP, CPVC, PVDFPIPE
  SIZEABCDIn.mmIn.mmIn.mmIn.mm ½"4.31101.3332.4621.948 ¾"4.61171.6392.8722.359 1"5.11301.9482.8722.564
  Series VB - Machined Models: PTFE ¾" 4.51141.9483.0762.051 1" 4.51141.9483.0762.051
  Series VBS - PVC, PP, CPVC, PVDF1-½"7.91932.5644.11043.5892"8.52093.0764.11043.5893"10.52674.31095.51405.5140
• 

  Ernesha

  sources:
  connectworld.net