Model PAF450, 16″ Offset Manhole, Non-DOT Pressure Relief Device


Model PAF450 incorporates a 10” (254mm) reclosing pressure relief valve (PRV) mounted to an offset 16” (406mm) clamp ring style manhole. It includes a P/V normal vent as well as provisions for mounting a vapor recovery valve and liquid level sensor. The PRV cover also serves as a quick open inspection hatch that incorporates a secondary safety catch. The manhole and clamp ring are certified and marked in accordance with 49CFR178.345-5 with a test pressure of 36 psig.

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.

PAF450 is also available in a self-latch model by designating part number 9842 in place of 9816. On self-latch models, stop bracket holds the PRV at a 91° position; if cover is inadvertently left open, movement of the tank will cause PRV cover to drop and catch to a semi-closed position. Standard model can be converted to a self-latching model with addition of 6807SL-KIT1.