ABSTRACT

Coffee Break Training: Hazardous Materials: 'Normal' Vents for Atmospheric Flammable and Combustible Liquid Tanks   [open pdf - 301KB]

"Vent devices are installed on some flammable and combustible liquid tanks to balance the pressure between the tank and atmosphere, and prevent damage when the tank is filled or emptied. These are known as 'vents for normal venting' or operating vents. (Coffee Break Training 2010-42 explained the purpose of emergency vents.) Tanks that store product at ambient pressure (or that operate at less than 2.5 psig [17.2 kPa]) are known as 'atmospheric' tanks. This category includes some aboveground and underground tanks. When tanks are filled, flammable and combustible vapors are expelled through the vent outlet. When an aboveground tank is warmed by the atmosphere, vapors also will escape. If vapors are heavier than air, they may accumulate on the ground and- depending upon atmospheric conditions-travel great distances where they may come into contact with an ignition source. The vent cap in today's photograph discharges downward, worsening the potential."

Report Number:
Coffee Break Training - Fire Protection Series No. FP-2011-9
Publisher:
Date:
2011-03-01
Series:
Copyright:
Public Domain
Retrieved From:
United States Fire Administration: http://www.usfa.fema.gov/
Format:
pdf
Media Type:
application/pdf
URL:
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