Guardian™ 407/412 Vacuum Breaker, 3″ and 4″ NPS Swivel Connection

The Betts’ Guardian™ vacuum breaker is a spring-loaded reclosing vacuum relief valve for use on a cargo tank’s vacuum relief system. The vacuum breaker is designed, tested and marked in accordance with US DOT 49CFR §178.345-10, §178.347-4 and §178.348-4.  The body and O-ring holder are constructed of 316L stainless steel with PTFE standard seals for compatibility with a wide range of products and temperatures.  The simplistic design allows for easy tear-down and maintenance.

  • Vibration resistant magnetic seat
  • Available ECTFE (Halar®) lined/coated
  • Body includes 1” and ¼” NPT ports
  • 3” or 4” NPS swivel mounting
  • Compact optimized flow design
  • Seal tabs on shroud and swivel nut
  • Multiple seal material options

MAWP: 50 psi [3.4 bar]
Minimum Bursting Pressure: 200 psi [13.8 bar]

Parts List

Product Details

Part NumberSize and ConnectionWeightMounting Details
RVV3S*3” Vacuum Valve
with 3” NPS Swivel Mounting
4.5 lbs. [2.0 kg]PTFE face seal on top of pipe nipple
RVV4S*4” Vacuum Valve
with 4” NPS Swivel Mounting
5.9 lbs. [2.7 kg]PTFE face seal on top of pipe nipple
• An example part number for a 3” Vacuum Breaker with PTFE seals would be RVV3ST.
• Vents can be specified with ECTFE (Halar®) lined/coated wetted components for aggressive chemical applications by adding an ‘L’ in the part number, as shown (e.g. RVVL3ST).
* Seal Material CodeMaterialTemp. Range
TPTFE-40°F to +400°F [-40°C to +204°C]
FFluorosilicone-50°F to +350°F [-45°C to +176°C]
KKalrez-20°F to +400°F [-28°C to +204°C]
VBFKM BLT-15°F to +400°F [-26°C to +204°C]
Set Pressure and Air Flow Capacity
SizeSet VacuumRated Air Flow Capacity
3"1.5 psig
[10.3 kPa]
18,000 SCFH @ 3.0 psig
[509 SCMH @ 206.8 kPa]
4"1.5 psig
[10.3 kPa]
18,000 SCFH @ 3.0 psig
[509 SCMH @ 206.8 kPa]
Notes: 1) Values shown are test values. Actual results may vary due to service conditions.
2) Set pressure is defined as point at which continuous flow is seen, felt or heard around the seat area. (nomenclature per ASME Section XII Part TR-110 and TTMA TB-126.)



Seal Kits & Accessories

Seal Kit part number: SK-RVVT

*Mounting gasket not included in seal kit

Spanner wrench part number: 75825EY