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VENTS THAT PROVIDE EMERGENCY PRESSURE RELIEF
In addition to the normal venting capacity provided by Protectoseal's
Pressure / Vacuum Relief Vents and/or Flame Arresters, every large above
ground flammable liquid storage tank should be provided with some means
of relieving excessive internal pressure caused by exposure of the tank
to a fire. Depending upon the strength of the tank structure, a vent sized
to handle the normal venting requirements (for day-to-day operations)
may be inadequate to handle the abnormal vapor efflux generated by heat
from an exposure fire. When a fire occurs near a flammable liquid storage tank, heat transmitted through the tank wall to the contents will cause the liquid to vaporize readily. In the case of petroleum based products, this vaporization may amount to roughly 30 or more cubic feet of vapor for every gallon of solvent vaporized. This generates a relatively high pressure within the confined area of the tank's vapor space. In the absence of sufficient emergency relief a tank rupture could occur, with disastrous effect on life and property and the environment. Explosions caused by such conditions may be readily avoided by providing adequate emergency relief vents which permit the vapors to escape from the tank. These emergency vents usually include pallet assemblies (as illustrated above) which are weighted to stay closed under normal pressure conditions and which open only when a predetermined pressure is attained, thus relieving the abnormal volume of vapor generated under the fire conditions described above. Emergency relief venting capacity may be provided by additional Pressure / Vacuum Conservation Vents, Emergency Pressure Vents, or Pressure / Vacuum Manhole Cover Vents. Emergency Pressure Vents |
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| PRODUCTS
| KEY CONTACTS
| UNDERSTANDING TANK SAFETY |
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