By definition, a flame arrester or also spelled flame arrestor and fire arrestor is a passive device that allows gas to pass through it but stops the propagation of a flame.
The unit is a passive device with no moving parts.
But before we start to describe flame arresters and how they work, it’s a good idea to start with a little background information. So let’s go back to how they first came to exist.
Modern Flame Arresters
Since Sir Humphrey's time, flame arresters of numerous varieties have been applied in many industries. All of them operate on the same principle: removing heat from the flame as it attempts to travel through narrow passages with walls of metal or other heat-conductive material. For instance, flame arresters made by most manufacturers employ layers of metal ribbons with crimped corrugations.
Flame arresters are used in many industries, including refining, pharmaceutical, chemical, petrochemical, pulp and paper, oil exploration and production, sewage treatment, landfills, mining, power generation, and bulk liquids transportation. In some cases, the flames involve exothermic (heat-producing) reactions other than oxidation. Processes which generate the combustible or reactive gases include blending, reacting, separation, mixing, drilling, and digesting. These processes involve numerous equipment configurations and gas mixtures.
Flame Arresters Element Design
To go into more detail, the flame arrester element is made up of a matrix of channels the walls of which quench the flame as it passes through by removing heat energy from the reaction. (The quenching mechanism of Maximum Experimental Safe Gap (MESG) is the principal on which flame arrester elements are designed.)
Basically, flame arrester elements are made up from a matrix of channels. The height and length of these channels is tuned offering the least resistance to gas flow whilst still quenching a flame.
There are a variety of element designs available in the market today with the most common being crimped ribbon. The main thing to remember is that the quench gap of an element will be different to the MESG of the explosion group it is certified for.
This product is designed and manufactured in rugged construction for extended life.
Unitized design with jackscrews for easy inspection and maintenance.
The standard body constructions are available in A216-WCB (Carbon Steel), A351-CF8 (SS304), A351-CF8M (SS316), and B26-319.F (Aluminum) materials suitable for most environments.
Cast carbon steel bodies are supplied in Epoxy finish coated, and stainless steel bodies are supplied in naturally uncoated.
Standard sizes range are from 1” to 16”, and available upon request.
Flanges are ANSI, JIS, and DIN standard, and other designs are available upon request.
The standard flame cell is suitable for NEC group D or IEA IIA gases.
Cells for other gas groups are available as additional extras.
Periodic inspections, maintenances, and replacements of the element is easily accomplished by simply removing tie-bolts and expanding the remaining jack screws.
Once the upper and lower body sections are expanded, the element is easily removed with the aid of a handle.
For distances or gas classifications outside these limits, the detonation arrester should be used.
Proper application of flame arresters is crucial for plant safety.
For corrosive applications, body and shell construction of stainless steel is suitable.
The Different Types of Flame Arresters
In function and performance of protection, basically flame arresters are available in two different major types/categories, they are Deflagration Flame Arresters and Detonation Flame Arresters.
In the kinds of installation, basically available in two different major types, they are Inline Flame Arresters and End of Line Flame Arresters.
And in the construction design, basically available in two different major models, that they all are advanced designed for the systems, as follows:
1. Model SFI
In-line Deflagration Flame Arresters
2. Model SFH
Inline Deflagration Flame Arresters
This model is designed to be better and smarter in maintenance, with quick and easy removable element.
Very easy to open up for maintenance and cleaning, that no need forced push out pipelines for removing element.
Freely able to be vertical and horizontal position of installation.
But the price is a little higher than the SFI model above.
Selecting In-Line Deflagration 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 20995 kPa(g) (3000 psig). Thus, the arrester must be structurally superior to standard low pressure deflagration arresters.
3. Model SFE
End of Line (Vent to Atmosphere) Deflagration Flame Arresters
End of line or vent-to-atmosphere type flame arresters work to prevent an atmospheric fire or explosion from entering an enclosure.
It allows 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 1920, 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.
Model SFE is designed to perform as an extinguishing barrier, which absorbs and dispels heat, reduces fire temperature and the oxygen level to stop the fire through layers of metal ribbons shaped with spiral-wound crimped-corrugated metal ribbons around a solid core inside a strong metal shell, maximizes ?ow capacity with minimum pressure drop.
This model is designed to provide a positive ?ame stop on low pressure tanks or piping systems containing ?ammable liquids or solvents having a low ?ash point.
This model not only provides exceptional protection against ?re from external ignition, but also offers maximum ?ow capacity.
It is mounted on the end of a vent pipe from the tank, or used with pressure vacuum vent on storage tanks either horizontally or vertically.
This model is designed, manufactured, and tested according to API 2000.
They are installed where it is not necessary to conserve vapors but where low flash point liquids must be protected against fire and explosion from exterior sources of ignition. Vapors are allowed to escape into the atmosphere and air can be drawn into the tank through the specially designed flame arrester grid assembly. If an ignition source outside the tank (unconfined deflagration) is encountered, the flame arrester provides protection for the tank's vapor space. Arresters are not for use in stabilized burning situations.
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.
The main points of concern when selecting a flame arrester for end-of-line applications are as follows:
• Hazardous group designation or MESG value of the gas
• Flame stabilization performance characteristics of the arrester compared to the system potential for flame stabilization for sustained periods of time
• Process gas temperature
• Pressure drop across the arrester during venting flow conditions, relative to the system's maximum allowable pressure and vacuum
• Materials of construction that meet the ambient and process conditions - for example, extremely cold climate, salt spray, chemically aggressive gas, etc.
• Connection type and size
• Instrumentation requirements
4. Model UFD
Inline Detonation Flame Arresters
Model UFD In-line Detonation Flame Arresters are designed for installation in gas pipelines. Detonation occurs when a flame travelling through the pipeline reaches supersonic velocities, usually as a result of the pipeline configuration or pipeline surface roughness. Changes in gas density and pressure causes the flame velocity to metamorphose from subsonic to supersonic.
The flame quenching element is designed to be three or four times the area of the pipe in which it is installed, and is assembled between two flanged reducing spools. The element comprises a tightly rolled scroll or scrolls of crimped stainless steel ribbon to form passages through which the vapor passes. The area of each passage determines level of protection that the element provides. This model has a maximum experimental safe gap (MESG) as per the standard, and is suitable for gas groups IIB and IIA.
The detonation flame arrester is more robust than the deflagration flame arrester, and contiguous scrolls have smaller MESGs to withstand higher pressures and to quench detonations. It should be installed in the pipeline where there is a significant distance between the unit and the potential source of ignition.
The unit is supplied with an earth point. Temperature sensor can be provided upon request. The element can easily be removed for cleaning or replacement.
Explosion level: IIA, IIB, IIC
Wide range of standard size 1” ~ 16”, with flange drilling according to ANSI, JIS, DIN, or API650.
Complete range of standard construction materials.
Easy inspection and maintenance, due to simple removal of element.
The net free area through all our flame arrester banks is three to four times the unit pipe size.
The design reduces surface friction, therefore, optimizing flow capacity and minimizing pressure drop.
The large surface area of the bank also improves heat dissipation.
Designed for deflagration proof.
Maximum protection, capacity, and ef?ciency with minimum pressure drop.
Capability of bi-directional flow and flame arresting.
Quick and easy removable element.
Very easy cleaning and maintenance.
Applicable for vertical and horizontal installation.
High quality corrosion and chemical resistance.
Maintenance of the bank element assembly is as simple as follows:
• Unit is provided with a handle for easy handling.
• Remove the tie rod bolts, and expand the remaining jackscrews.
• This extends the end housings allowing the bank assembly to be easily removed.
• The bank element is quickly inspected or cleaned and replaced between the end housings.
1. Deflagration or detonation protection
2. Inline or end of line type
4. Body material
6. Type of connection flange
7. Flange standard based on ANSI, JIS, DIN, or API
8. Rating class of flange