94225 Emergency Vent & Manhole Cover (Pressure & Vacuum)

The Shand & Jurs 94225 Emergency Vent and Manhole Cover provides emergency relief of excessive internal pressure and vacuum beyond that provided by tank conservation vent requirements.

The weight loaded pressure vent section employs a flexible diaphragm or an Expanda-Seal diaphragm (option), which provides a tight seal between the pallet and seat. Special diaphragm materials are available for most product environments. Corrosion resistant pressure/vacuum seat is standard.

The pressure pallet starts to lift when set pressure is approached. Flow efficiency rises rapidly to approximately 60% of a perfect orifice at 40% excess of the set pressure. At higher overpressure, the flow efficiency approximates 75%.

Vacuum relief is spring operated and adjustable, which permits a wide range of vacuum settings without affecting the pressure set point.

For tank venting or examination, the entire hinged cover may be lifted open in a matter of seconds, offering clear passage through the unobstructed opening. Since no gasket replacement or unbolting is necessary, this vent eliminates the expensive manpower needed to put conventional manhole covers back in operation.

Model 94225 is available for standard ANSI and API flat face flange connections. Raised face connections and special flanges are available including EN1092-1.

Pallet construction permits a wide variety of pressure settings. See specifications for various pressure settings of all vent sizes.


  • Design incorporates pressure and adjustable vacuum relief
  • 16″, 18″, 20″, 24″, and 30″ ANSI sizes
  • 20″ and 24″ API roof manhole sizes
  • “Self-energizing” Expanda-Seal diaphragm (optional) assures a tight seal
  • Hinged cover provide precise sealing and safety
  • No unbolting of vent for seal replacement or tank examination

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94221 Emergency Vent And Manhole Cover (Pressure And Vacuum)