環境污染的標準嚴格執法，已對易燃液體儲存罐的巨大影響。而不是驅逐蒸氣進入大氣，這種趨勢已經對連接或多個坦克歧管通過共同管道到一個中央處理單元。這些已關閉的管道系統，或蒸氣回收/收集系統，創造了獨特的易燃氣體的安全隱患。管道運行在這些汽體回收系統往往是更長，更復雜。點火的潛在來源，實際上可能是在蒸汽收集系統本身存在。一個管道系統內可以導致點火火焰前面，可以加速非常迅速，并產生極高的壓力。低速，低壓密閉爆燃可以很容易地進入一個高速，高壓密閉爆燃和過渡然后到爆炸，這是一個在火焰前在蒸氣/空氣混合物的聲音速度移動。“爆炸”避雷器是專門設計來阻止和撲滅爆炸，爆燃和潛水承壓爆燃。認為是對尾線和排氣線/直插式阻火器放置的位置就點火源的限制不適用于引爆避雷器。

FLAME & DETONATION ARRESTERS

Flammable liquids are volatile in nature. As they evaporate, they may produce ignitable vapor/air mixtures. Such hazardous conditions are commonly encountered in chemical, petrochemical, petroleum and pharmaceutical plants where the storage, transfer and collection of flammable liquids are part of their daily operations.

Flame arresters and detonation arresters are passive, mechanical device installed on a storage tank nozzle or in a flammable vapor piping system. The arresters' functions are: (1) to allow the passage of vapor under normal operating conditions and (2) to stop and extinguish any flame front propagating through the flammable vapor/air mixture under emergency conditions. Stopping the flame protects the storage tank, or the equipment located in the piping system, from the catastrophic damage that may result from an uncontrolled ignition. A variety of arrester designs are available. The choice of a proper arrester depends on factors such as the location of the arrester with respect to the ignition source and the flammable properties of the vapor/air mixture.

The Protectoseal Company recommends that the National Electric Code (NEC) Article 500, rankings of various chemicals be used, whenever possible, to determine the suitability of a flame or detonation arrester for use which a particular chemical.

One common flame arrester configuration is mounted at the end of a storage tank vent pipe and is identified as an "END-OF-LINE" flame arrester. This arrester permits normal tank breathing, while preventing the flashback of an unconfined deflagration (the ignition of the vapor cloud in the open atmosphere) from flashing back past the arrester into the piping and the tank's vapor space.

Flame arresters are at times mounted directly upstream of pressure / vacuum relief vents, or are connected to short runs of open vent outlet piping. These devices, known as "VENT-LINE / IN-LINE" flame arresters are designed with flanged or threaded mounting connections on both the inlet and outlet. It is possible for a flammable vapor / air mixture to ignite within the confined space of the short outlet pipe or within the vent body. Such an ignition is referred to as a confined deflagration. The flame speed is slow and pressures within the vent piping are relatively low. The Vent-Line / In-Line Flame Arrester is designed to stop this type of flame front. Note: these arresters have very specific limitations as to where they can be properly located within the system.

Strict enforcement of environmental pollution standards has had a dramatic impact on tank storage of flammable liquids. Rather than expelling vapors into the atmosphere, the trend has been toward the connecting or manifolding of multiple tanks through common piping to a central processing unit. These closed piping systems, or vapor recovery / collection systems, have created unique flammable vapor safety hazards. The piping runs in these vapor recovery systems tend to be longer and more complex. Potential sources of ignition may actually be present within the vapor collection system itself. An ignition within a piping system can result in a flame front that accelerates very rapidly and generates extremely high pressures. A low speed, low pressure confined deflagration can readily transition into a high speed, high pressure confined deflagration and then to a detonation, which is a flame front moving at the speed of sound in the vapor/air mixture. "DETONATION" arresters are specifically designed to stop and extinguish detonations, confined deflagrations and unconfined deflagrations. The limitations that are placed on the location of end-of-line and vent-line / in-line flame arresters with respect to the ignition source do not apply to detonation arresters.