Betts PAF manhole with integral 406-98 Surge Suppression Pressure Relief Valve is the proven leader for cargo tank longevity, protection and safety.
The 406-98 incorporates a 10” (254mm) reclosing pressure relief valve (PRV) that satisfies primary pressure relief for specification US DOT406 and TC406 cargo tanks. The PRV meets the dynamic pressure surge requirements of 49CFR§178.345-10(b)(3)(ii) with less than one liter leakage as tested per TTMA RP No. 81. The PRV cover also serves as a quick-open inspection hatch that incorporates a secondary safety catch. PPVL models include a 6496 P/V normal vent.
The 20” (508 mm) clamp ring style manhole is certified and marked in accordance with 49CFR178.345-5 with a test pressure of 36 psig.
PAF 406-98 is also available in a self-latch model by designating part number L763 in place of L720. On self-latch models, a stop bracket holds the PRV at a 91° position; if the cover is inadvertently left open, movement of the tank will cause PRV cover to drop and catch to a semi-closed position.
Stainless versions of the PRV are available. For manhole replacement on MC306 cargo tanks, see Betts’ line of PAF306 surge manholes.
BTS Manhole 20" Center PAF-406
