Catalog

3 1/2" Aluminum Vapor Valve
Sequential Interlock

• Air Actuated Sequential Operation
• Stainless Trim with PTFE Seals
• Inward Opening

Betts 3 1/2" Sequential Vapor Valves are designed for use as positive vapor recovery valves on cargo tanks during loading and unloading. Sequential interlock design allows the vapor valve to be plumbed in series with the emergency valve to ensure the vapor valve is open before the emergency valve. Vapor valves can also be plumbed to operate independently of the emergency valves, if desired. Internal interlock device guarantees that all vapor valves and emergency valves will close fully when air pressure is released, regardless of their location in the plumbing system.

Available in two configurations - bolted design mounts in 20" offset PAF manhole cover using eight 3/8-16UNC bolts (included), while threaded design mounts in 16" offset PAF manhole. Both versions meet all requirements for loading/unloading venting devices on MC306 and DOT406 cargo tanks and are tested and marked with a test pressure of 36 psig in accordance with 49CFR178.345-5(f).

Inward opening action prevents loss of lading due to surge pressure during a roll-over accident. All moving parts are internal to minimize chance of freeze-ups during cold weather. Aluminum bodies with stainless trim minimize corrosion and PTFE seals in contact with vapors ensure compatibility with a wide variety of products.

Service Temperature Ratings (ºF)
Standard Valves -20 ºF to 200 ºF
w/ '023' suffix (fluorosilicone) -80 ºF to 400 ºF

Note: Temperature ratings are based on published information and may vary due to actual conditions.