Model 8920

Description:

The Model 8920 manway pressure and pressure /vacuum relief vents provide emergency pressure relief beyond that furnished by the normal pressure vent for atmospheric and low pressure tanks, as well as a convenient access for tank cleaning, inspection and repair. Emergency relief vents provide relief from excessive internal pressure which may be caused by an abnormal condition; such as ruptured internal heating coils, an external fire, a failure of the tank blanketing system, a sudden cooling of the tank or a break in the tank wall.

Available Sizes

• 16" (DN400)
• 18" (DN450)
• 20" (DN500)
• 24" (DN500)

End Connections

Flanged

Features

• Easy Inspection and Maintenance: The 8900 Series vents are rugged in design, yet light weight for easy handling, inspection and maintenance. The pressure pallet assembly can be removed to allow unobstructed access to the tank for tank entry, inspection and repairs.
• Maintains Accurate Pressure Settings: Vacuum setting ranges from 0.2 to 4 oz/in². Vacuum set point pressure can be easily changed without dis-assembly of the vent. Seat leakage meets or exceeds API Standard 2000.
• Air-Cushion Pallet Design: Utilizes a flat diaphragm in place of an O-ring for sealing. The thickness of the diaphragm is based on the vent size and the customer specified set point. It forms around the seat to provide a tight seal due to the air cushion pallet design.
• Modular: As part of the Valve Concepts, Inc. modular vent product line, the 8900 Series can be converted from pressure/vacuum to pressure only relief design. Available as either a top guided (spring loaded) or hinged (weight-loaded) vent.

Technique

The pressure pallet assembly provides an effective vapor-tight seal when the tank is not under emergency conditions. If the tank out breathing requirements exceeds the capability of the normal pressure relief vent, under emergency conditions, the pallet assembly lifts off the seat to allow escape of vapors, preventing damage to the tank due to excess pressure. When the excess pressure is relieved the pallet assembly will reseat to again provide a vapor-tight seal.