Request a Project Discussion: or Flame arresters consist of screens, perforated plates, and slots that are enclosed in a frame. The case helps to absorb the heat of a flame and extinguish it.
A standard flame arrester has many small tubes that help to produce the required venting capacity while preventing the passage of flame. Selecting in-line flame arresters The various dynamic states explained earlier for confined flames can be very dangerous for a process system due to the tremendous energies associated with detonation pressure and flame velocity.
Things happen fast and can turn catastrophic. These multiple dynamic states increase the challenge of providing a flame arrester product or products which stop the flame and withstand the enormous pressures caused by explosions within the confined piping. The very wide range of possible behavior for a confined flame causes two particular problems for flame arrester products.
First, the high-pressure deflagration and stable detonation states have very stable kinetics of burning, and the flame is moving very fast. Therefore the arrester must be able to absorb the flame's heat much faster than is required by standard low-to-medium-pressure deflagration conditions. Second, the instantaneous impulse pressures caused by the shock waves of overdriven detonation subject the arrester to forces of up to kPa g psig.
Thus, the arrester must be structurally superior to standard lowpressure deflagration arresters. End of line or vent-to-atmosphere flame arresters allow free venting in combination with flame protection for vertical vent applications. They prevent flame propagation by absorbing and dissipating heat using spiral wound crimped ribbon stainless steel flame cells. End-of-line flame arresters are used in applications such as petroleum storage tank vents.
The classic application is in preventing fire in the atmosphere from entering an enclosure. Around , for instance, flame arresters began to be installed on vents on oilfield storage tanks. They keep the tanks from exploding when gas flowing from the vents is struck by lightning.
Conversely, some end-of-line flame arresters prevent fire in an enclosure from igniting an explosive atmosphere such as in a refinery. For instance, flame arresters may be installed in furnace air inlets and exhaust stacks.
Selecting end-of-line flame arresters End-of-line deflagration flame arresters are designed for unconfined flame propagation, also referred to as atmospheric explosion or unconfined deflagration. They simply bolt or screw onto the process or tank connection. These designs incorporate well-established but simple technology.
Most use a single element of crimped wound metal ribbon that provides the Heat Transfer needed to quench the flame before it gets through the arrester element. A flame arrestor mainly consists of a housing, an element and connections to secure it to pipe work or equipment.
Because of its construction, the element will cause a pressure drop or an obstruction to process flow. In order to mitigate this increased resistance to flow, the element area is usually larger than the cross sectional area of the pipe work. Larger elements also have a greater heat capacity. All flame arrestors are designed to allow gases or liquids to pass through while preventing flames or sparks from creating an explosion or expanding into a larger fire.
However, their range of style and size varies tremendously to fit each application. End-of-line flame arrestors are fitted to the end of a pipe line or exit to a vessel to prevent flames from entering, and not, as is sometimes believed, to prevent the flame exiting the pipe or vessel. Without a weather-hood, they may be mounted in almost any orientation, but inverted mounting is not recommended as this increases the risk of heat being trapped thus causing a flash back.
With a weather-hood incorporated, they should be fitted in a conventional vertical orientation and be used outside exposed to rain and snow. In-line flame arrestors are fitted in piping systems to protect downstream equipment. The layout shown below is typical although it is also possible that the source of ignition could cause the flame to travel with the gas flow.
If the flame could come from either direction then a bi-directional flame arrestor is required. In-line flame arrestors can be either deflagration or detonation arrestors depending on the conditions under which they are to be used. Pipe orientation is usually not a problem unless liquid is entrained in the gas flow and would tend to collect in the arrestor. In such situations, an eccentric flame arrestor housing may be fitted to allow collection and drainage of the liquid.
These are so called because they are designed to protect systems in which a flame may start within a container whose cross sectional area is somewhat larger than the flame arrestor element or the vent pipe and the desire is to prevent the flame leaving the container. They may be simply an element, an end-of-line arrestor or an in-line arrestor. Extreme care must be taken when considering such a situation as it is not possible to predict the conditions that the flame arrestor will have to handle because the volume of hot gases passing through the arrestor will exceed the volumes produced for conventional in-line arrestor flame testing.
These systems, commonly used in many industries, may be called vapor control systems. The gases which are vented to atmosphere or controlled via vapor control systems are typically flammable. If the conditions are such, that ignition occurs, a flame inside or outside of the system could result, with the potential to do catastrophic damage.
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