Model PAF 450, 10″ Fill, Non-DOT Pressure Relief Device

Model PAF450 incorporates a 10” (254mm) reclosing pressure relief valve (PRV) mounted to weld-in 10” (254mm) collar. It includes a P/V normal vent. The PRV cover also serves as a quick open inspection hatch that incorporates a secondary safety catch.

The PAF450 was legal for installation on US DOT MC306 cargo tanks prior to August 31, 1998. Per 49CFR180.405(h)(2), a properly functioning PAF450 can be repaired and maintained but if the entire assembly needs to be replaced, it must be a PRV that meets the less-than 1 liter surge leakage requirement of 49CFR178.345(b)(3)(ii). Therefore, Model PAF450 is NOT permitted as a replacement on MC306 or DOT406 cargo tanks but can be installed on non-specification tanks or on tanks built and operated in countries where regulations permit. See Betts’ complete line of PAF406 and PAF306 PRV’s that meet requirements of less-than 1 liter surge leakage.

Product Details

Part NumberCollar MaterialStrongback and LatchPRV CoverNormal VentWeight
304 Stainless
316 Stainless
Steel Zinc-plated
Steel Zinc-plated
304 Stainless
304 Stainless
6238AL Aluminum
6238AL Aluminum
6238AL Aluminum
6238AL Aluminum
18.0 lbs (8.2 kg)
13.7 lbs (6.2 kg)
16.5 lbs (7.48 kg)
16.5 lbs (7.48 kg)
*Replace asterisk in part number to designate gasket material.

Example Assembly: FVA9710BAB

(10” PAF Pressure Relief Device, Zinc Steel Plated Strongback and Latch, Aluminum Collar + Black Nitrile Buna-N)
LetterGasket Material
BNitrile (Buna-N)
WWhite Hypalon
TPTFE (w/ Nitrile or Silicone Core)
  • Suffix “059” option for padlock loop installed in strongback.
  • Prefix “FSA” for both 6238AL normal vent & 6234AL inbreathing vent included.
  • Collar material should correspond with tank shell material. When welding collars to tank, care should be taken to insure collar remains flat and round with use of a welding fixture if necessary.

Technical Specifications

PAF450 Pressure Relief Valve6238AL Normal Vent (P/V Vent)
Set PressureRelated Air Flow Capacity
(Cubic feet per hour)
Pressure SetPressure Rated Flow CapacityVacuum SetVacuum Flow Capacity
Min 3.0 psig
(Min 20.7 kPa)
375,000 SCFH @ 5 psig
(10.618 SCMH @ 34.5 kPa)
Max 1.0 psig
(max 6.8 kPa)
1,750 SCFH @ 3 psig
(49 SCMH @ 20.7 kPa)
Max .375 psig
(Max 2.5 kPa)
3,350 SCFH @ 1 psig
(95 SCMH @ 6.8 kPa)