Arrestors

Some conservation vents (pressure-vacuum) have built-in flame arrestors on a single compact unit mounted on the tank vent. Refer to API Safety Data 2210, Flame Arrestors for Tank Vents. 

A special study [74] was commissioned by the American Petroleum Institute (API) entitled Mitigation of Explosion Hazards of Marine Vapor Control Systems. The report examines the effects of deflagrations and detonations in pipes in the region of detonation flame arrestors. The primary objective was to resolve potential 

Applied Process Design for Chemical and Petrochemical Plants 

A = wetted surface area, in square feet (see Table 3, Footnote a). 

The Code [26] allows pilot operated vent control valves provided the vent valve can operate automadcally in case the pilot valves/system failed. 

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Storage of Flammable Materials. The preferred storage for flammable Hquids or gases is in properly designed tanks. Floating roof tanks frequently are used in the petroleum industry for flammable cmdes and products (see Tanks and pressure vessels). The vents on cone roof tanks should either be equipped with flame arrestors or the vapor space above the contents should be inerted with a nonflammable gas or vapor, unless the flash point is weU above the maximum ambient temperature, the contents are not heated above the flash point, and the tank is not exposed to other tanks containing flammable Hquids. 

A high temperature thermocouple uses sihcon carbide (146). It is also used in lightning arrestors to protect high tension power lines, and in high loss factor microwave attenuators (147). 

When acetylene is recovered, absorption—desorption towers are used. In the first tower, acetylene is absorbed in acetone, dimethylformarnide, or methylpyroUidinone (66,67). In the second tower, absorbed ethylene and ethane are rejected. In the third tower, acetylene is desorbed. Since acetylene decomposition can result at certain conditions of temperature, pressure, and composition, for safety reasons, the design of this unit is critical. The handling of pure acetylene streams requires specific design considerations such as the use of flame arrestors. 

Water hammer arrestors, if correctly sized, placed, and maintained, will reduce water hammer by providing a controlled expansion chamber in the system. As the forward motion of the water column in the pipe is stopped by the valve, a portion of the reversing column is forced into the water hammer arrestor. The water chamber of the arrestor expands at a rate controlled by the pressure chamber and gradually slows the column, preventing hydraulic shock. 

If a check valve is used in a system without an arrestor, excessive pressure may be exerted on the system when the reversing water column is violently stopped by the check valve. If a float-type air vent is located between the check valve and the closing valve, the float could easily be ruptured. 

Appropriate gas/vapour/fume/pressure venting, e.g. flame arrestors, scrubbers, absorbers, stacks Ensure adequate natural or forced general ventilation of the storage area Provide adequate, safe lighting... 

Arc Extinguishing Plastics 1964 E Injection or compression molded and extruded Fuse tubing, lightning arrestors, circuit breakers, panel boards... 

The hazard tree also helps identify protection devices to include in equipment design that may minimize the possibility that a source will develop into a condition. Examples would be flame arrestors and stack arrestors on fire tubes to prevent flash back and exhaust sparks, gas detectors to sense the presence of a fuel in a confined space, and fire... 

Vessel is final scrubber in a flare, relief, or vent system, is designed to withstand maximum built-up back-pressure, and has no internal or external obstructions, such as mist extractors, back-pressure valves, or flame arrestors. 

A fire in a bulk storage facility at Coode Island, Melbourne, Australia, in August 1991 caused extensive damage and many complaints about the pollution caused by the smoke plume, but no injuries. The tank vents were connected together and piped to a carbon bed vapor recovery system. There were no flame arrestors in the pipework. Whatever the cause of the initial fire or explosion, the vent collection system provided a means of spreading the fire from one tank to another. 

In the past it was difficult to prevent the spread of explosions through vent systems, as flame arrestors were effective only when located at the ends of pipes. Effective inline detonation arrestors are now availabe. Like all flame arrestors they will, of course, need regular cleaning, something that is often neglected. In other cases, when tanks have been over-... 

There are, however, two cases in which flame arrestors in vent stacks are justified ... 

If the gas being vented can decompose without the addition of air an example is ethylene oxide. Whenever possible, such gases should be diluted with nitrogen. If this is not always possible, a flame arrestor may be used. 

In the vent pipes of storage tanks containing a flammable mixture of vapor and air (Section 5.4.1). Such flame traps should be inspected regularly and cleaned if necessary. Section 5.3 a described how a tank was sucked in because the flame arrestors on all three vents had not been cleaned for two years. 

A type of flame arrestor that can be easily removed for inspection without using tools is described in Reference 4. 

The common theme of many of these items is that blowdown lines and flare and vent stacks should be kept simple because they are part of the pressure relief system. Avoid flame arrestors, molecular seals, water seals, and U-bends. Avoid steam, which brings with it laist and scale and may freeze. 

Open vents, especially those on storage tanks, are often fitted with flame aiTestors. If the vents, and in particular the flame arrestors, are not... 

Figure-8 plate Flame arrestor Flashlight Fractionation Gasoline... 

CASE III IGNITION ( ) NEAR ARRESTOR FIGURE 5-12. Effect of ignition source location—nonflowing system. 

Langford, B., Palmer, K. N., and Tonkin, P. S. 1961. The Performance of Flame Arrestors Against Flame Propagating m Various Fuel/Air Mixtures. Fire Research Station Note No. 486. Fire Research Station, Borehamwood, Herts., England. 

Climate and natural litizards should be evaluated. Lightning arrestors should be installed to prevent lighuiing from directly striking flammable areas. For outdoor operations, temperatures must be considered. 

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