406 AND 306 PRESSURE/VACUUM NORMAL VENT

• Dual Purpose Vent
• Roll Over Protection
• Compact Design
• Interior Mount

The Betts’ Normal Vent is the proven standard of the fuel transport industry. Normal Vents (breather vents) are utilized to normalize internal tank vacuum and pressure, which is critical to keep the cargo tank pressure within safe design limits. This vent incorporates a unique weighted roll-over block which increases the set pressure of the vent in a roll over situation but does not act as a shutoff device like other manufacturer’s designs. This feature differentiates the Betts’ design and allows the vent to maintain its primary function as a pressure/vacuum relief device in all situations. The vent is flow tested and marked in accordance with DOT requirements.

Two standard vent styles are available; one for MC306 cargo tanks and the other for DOT406 cargo tanks. Model 6496, DOT406 style, has a pressure setting per 178.346-3(b)(2) of “not less than 1 PSIG” and a vacuum setting per 178.346-3(c)(2) of “no more than 6 ounces”.

NOTE: While normal vents provide limited vapor venting during loading/unloading, it is recommended that positive vapor valves (typically air operated) be provided when loading/unloading with the manhole closed. If positive vapor valves are not used, insure normal vent is functioning properly or open manhole cover before beginning loading/unloading. Failure to do so may result in head reversals or other tank failure.