Guardian™ 407/412 Combo Pressure/Vacuum Valve, 3″ and 4″ NPS Connection

The Betts’ Guardian™ combination valve is a spring-loaded reclosing pressure and vacuum relief device/valve for use on a cargo tank’s primary pressure and vacuum relief system. The combination relief valve 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.

  • Vibration Resistant Magnetic Seat
  • Available ECTFE (Halar®) lined/coated
  • 3” or 4” NPS mounting
  • Compact optimized flow design
  • Seal tabs on shroud and body
  • Multiple seal material options

 Minimum Bursting Pressure: 200 psi [13.8 bar]

Parts List

Product Details

Part NumberSize and ConnectionWeight
RVC3N*-**3” Combo Valve w/ 3” NPS Mount14.9 lbs. [6.8 kg]
RVC4N*-**4” Combo Valve w/ 4” NPS Mount14.5 lbs. [6.6 kg]
• An example part number for a 3” Valve for a 25 MAWP tank with PTFE seals would be RVC3NT-25.
• 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. RVCL3NT-25).
* 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]
Valve Size** Code
Tank MAWP
Set PressureRated Pressure Air Flow Capacity
(out-breathing)
Water Flow Rate (Out)Set VacuumRated Vacuum Air Flow Capacity
(in-breathing)
3"25 psig. [1.72 bar]30 psig [2.06 bar]360,569 SCFH @ 40 psig [10,210 SCMH @ 2.75 bar]

409,559 SCFH @ 45 psig [11,597 SCMH @ 3.10 bar]
980 gpm @ 40 psig.

1,050 gpm @ 45 psig.
1.5 psig [10.3 kPa]12,500 SCFH @ 3.0 psig
[353 SCMH @ 206.8 kPa]
3"30 psig. [2.06 bar]36 psig [2.48 bar]409,559 SCFH @ 45 psig [11,597 SCMH @ 3.10 bar]1,050 gpm @ 45 psig.1.5 psig [10.3 kPa]12,500 SCFH @ 3.0 psig
[353 SCMH @ 206.8 kPa]
3"35 psig. [2.41 bar]42 psig [2.89 bar]457,740 SCFH @ 52.5 psig [12,961 SCMH @ 3.62 bar]1,075 gpm @ 52.5 psig.1.5 psig [10.3 kPa]12,500 SCFH @ 3.0 psig
[353 SCMH @ 206.8 kPa]
3"40 psig. [2.75 bar]48 psig [3.31 bar]514,539 SCFH @ 60 psig [14,570 SCMH @ 4.13 bar]1,100 gpm @ 60 psig.1.5 psig [10.3 kPa]12,500 SCFH @ 3.0 psig
[353 SCMH @ 206.8 kPa]
4"25 psig. [1.72 bar]30 psig [2.06 bar]365,828 SCFH @ 40 psig [10,359 SCMH @ 2.75 bar]

421,629 SCFH @ 45 psig [11,939 SCMH @ 3.10 bar]
1,000 gpm @ 40 psig.

1,100 gpm @ 45 psig.
1.5 psig [10.3 kPa]12,500 SCFH @ 3.0 psig
[353 SCMH @ 206.8 kPa]
4"30 psig. [2.06 bar]36 psig [2.48 bar]421,629 SCFH @ 45 psig [11,939 SCMH @ 3.10 bar]1,100 gpm @ 45 psig.1.5 psig [10.3 kPa]12,500 SCFH @ 3.0 psig
[353 SCMH @ 206.8 kPa]
4"35 psig. [2.41 bar]42 psig [2.89 bar]487,967 SCFH @ 52.5 psig [13,817 SCMH @ 3.62 bar]1,150 gpm @ 52.5 psig.1.5 psig [10.3 kPa]1.512,500 SCFH @ 3.0 psig
[353 SCMH @ 206.8 kPa]
Replace ** in Part Number to Designate Cargo Tank MAWP in PSIG
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-RVCT

*Mounting gasket not included in seal kit

Spanner wrench part number: 75825EY

Dis-assembly T-wrench part number : 75819ZC