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FIG 748A

Pressure Vacuum Vent - 2” Aluminum

Pressure vacuum vent designed for installation on top of the vent pipe of an aboveground or underground storage tank. Poppets seal vapors in the tank when pressure is equalized. The vent allows the tank to “breathe” during filling and dispensing operations. This vent must be used in conjunction with an emergency vent. It is recommended that the opening pressure setting is set below that of the emergency vent so the normal vent operates first. Settings are approximate.

NOTE: Normal vents such as pressure vacuum and updraft vents for aboveground storage tanks should be sized according to NFPA 30 (2012) 21.4.3.

WARNING: DO NOT FILL OR UNLOAD FUEL FROM A STORAGE TANK UNLESS IT IS CERTAIN THAT THE TANK VENTS WILLOPERATE PROPERLY. Morrison tank vents are designed only for use on shop fabricated atmospheric tanks which have been built and tested in accordance with UL 142, NFPA 30 & 30A, and API 650 and in accordance with all applicable local, state, and federal laws. In normal operation, dust and debris can accumulate in vent openings and block air passages. Certain atmospheric conditions such as a sudden drop in temperature, below freezing temperatures, and freezing rain can cause moisture to enter the vent and freeze which can restrict internal movement of vent mechanisms and block air passages. All storage tank vent air passages must be completely free of restriction and all vent mechanisms must have free movement in order to insure proper operation. Any restriction of airflow can cause excessive pressure or vacuum to build up in the storage tank, which can result in structural damage to the tank, fuel spillage, property damage, fire, injury, and death. Monthly inspection, and immediate inspection during freezing conditions, by someone familiar with the proper operation of storage tank vents, is required to insure venting devices are functioning properly before filling or unloading a tank.

Product Features

Standard Features

Vents outward and upward in compliance with NFPA 30

Tri-polar mounting screws for mounting exhaust hood in any of three positions

Optional dryer connections accommodate the installation of desiccant dryers on vacuum connection

Optional pressure discharge hood facilitates piping pressure relief to desired discharge point


Construction Details

  • Body and hood: Aluminum
  • Poppets: Brass
  • Seats: Passivated aluminum
  • Screens: Stainless steel

Product Ordering Instructions

Figure Suffix Size Description Weight (lbs)
748A 0100 AV 2” 2oz/sq.in. Pressure Vacuum Vent - Brass Internals 6.75
748A 0200 AV 2” 4oz/sq.in. Pressure Vacuum Vent - Brass Internals 7.5
748A 0300 AV 2” 6oz/sq.in. Pressure Vacuum Vent - Brass Internals 8.25
748A 0400 AV 2” 8oz/sq.in. Pressure Vacuum Vent - Brass Internals 9.25
748A 0500 AV 2” 12oz/sq.in. Pressure Vacuum Vent - Brass Internals 10.5
748A 0600 AV 2” 16oz/sq.in. Pressure Vacuum Vent - Brass Internals 11
748A 0700 AV 2” 2oz/sq.in. Pressure Vacuum Vent-Brass Internals w/Dryer Connection
6.75
748A 0800 AV 2” 4oz/sq.in. Pressure Vacuum Vent-Brass Internals w/Dryer Connection 7.5
748A 0900 AV 2” 6oz/sq.in. Pressure Vacuum Vent-Brass Internals w/Dryer Connection 8.25
748A 1000 AV 2” 8oz/sq.in. Pressure Vacuum Vent-Brass Internals w/Dryer Connection 9.25
748A 1100 AV 2” 12oz/sq.in. Pressure Vacuum Vent-Brass Internals w/Dryer Connection 10.5
748A 1200 AV 2” 16oz/sq.in. Pressure Vacuum Vent-Brass Internals w/Dryer Connection 11