Ignited vents

RADIATION AND SPACING FROM FLARES AND IGNITED VENTS... 

A simplified graphical procedure is presented for the determination of (horizontal) and (vertical), the flame mid-point coordinates for flares and ignited vents.Figures 12 and 13 provide graphs, one for and one for Z,., which... 

Figure 12. Flare center for flares and ignited vents.

Step 2 Select the appropriate flame emissivity factor F, based on flare gas composition. For ignited vents, lower values are recommended. The following are emissivity values reported from the literature ... 

Catch basins and manholes should have a vent of 4-inch minimum size. In areas of furnaces or other fired equipment or sources of possible ignition, vents should be run underground at least 100 ft. from the source of possible ignition and 10 feet above grade in a safe location. 

Dust deposits Static electricity and self-ignition Venting or suppression for toxic dust... 

Figure 4.19 Flame center for flares and ignited vents vertical distance (SI units). (Courtesy American Petroleum Institute, 1220 L Street, NW, Washington, D.C.)...

Vented risers should be provided on most cooling towers to release only light hydrocarbon leakage from the cooling water before the spray header. No ignition or source of spark should be within 30 m of the vented riser. 

Occurrence. Carbon monoxide is a product of incomplete combustion and is not likely to result where a flame bums in an abundant air supply, yet may result when a flame touches a cooler surface than the ignition temperature of the gas. Gas or coal heaters in the home and gas space heaters in industry have been frequent sources of carbon monoxide poisoning when not provided with effective vents. Gas heaters, though properly adjusted when installed, may become hazardous sources of carbon monoxide if maintained improperly. Automobile exhaust gas is perhaps the most familiar source of carbon monoxide exposure. The manufacture and use of synthesis gas, calcium carbide manufacture, distillation of coal or wood, combustion operations, heat treatment of metals, fire fighting, mining, and cigarette smoking represent additional sources of carbon monoxide exposure (105—107). 

Detonation arresters are typically used in conjunction with other measures to decrease the risk of flame propagation. For example, in vapor control systems, the vapor is often enriched, diluted, or inerted, with appropriate instrumentation and control (see Effluent Disposal Systems, 1993). In cases where ignition sources are present or pre-dic table (such as most vapor destruct systems), the detonation arrester is used as a last-resort method anticipating possible failure of vapor composition control. Where vent collec tion systems have several vapor/oxidant sources, stream compositions can be highly variable and... 

Locate explosion vents as close as possible to the most likely ignition sources. 

Eliminate turned-down vents from safety relief valves, i.e., upside down U. Possible accidental ignition of releases from such vents wiU likely result in flame impingement on the top external surface of the tank, above the internal wetted surface. BLEXT Some means to handle rainwater from a desirable upward vertical vent have been listed by Bodurtha (ibid., April 1988). Moreover, a safety relief valve must function properly when required and must be sized properly to help prevent an explosion. 

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