What is a spelled arrestor
A Flame Arrestor is a device fitted to the opening of an enclosure or to the connecting pipe work in a system of enclosures and which allows gases, liquids, etc. to pass through it but prevents the transmission of a flame in order to prevent a larger fire or explosion. In process operations with combustible gases, flame arrestors help in mitigating the risk of spreading of fire and thus limit the impact of an explosive event. When used properly, flame arrestors can prevent catastrophic damage and loss of life. Anyone involved in selection and purchase of flame arrestors needs to understand how these products work, their advantages and their performance limitations. In this article we will try to cover the basics of the technology and terminology of flame arrestors and the types available.
Uses of a Flame arrestor
The uses of a flame arrester include:
- Stopping the spread of an open fire
- Limiting the spread of an already occurred explosion
- Preventing potentially explosive mixtures from igniting
- Confining fire within a controlled location
- Stopping the propagation of a flame traveling at subsonic velocities
Why Use a Spelled Arrestor?
One of the greatest dangers involved with the transport or storage of flammable liquids or gases is that ignition of the flammable vapor may occur, resulting in fire or worse, an explosion.
Accidental ignition of the flammable mixture will result in a flame that will travel through the unburnt mixture until the fuel is consumed by the reaction. In an enclosed space, such as a vessel or a pipe, the significant temperature increase of the mixture caused by the combustion process will lead to a rapid increase in the volume of the gas mixture. Resulting in a increase in pressure which will further accelerate the flame front. Failure to stop a flame can result in catastrophic damage to equipment, loss of production.
Types Of Arrestors
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 Arrestor
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 Arrestor
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.
MATERIAL OF CONSTRUCTION
| CODE | AL | C.I. | C.S | . S.S. 304 | S.S. 316 | |||
| BODY | ALUMINIUM A | 126 CL B | A 126 WCB | A 351 CF 8 | A 351 CF 8M | |||
| ELEMENT RING | S.S. 304 | S.S. 304 | S.S. 304 | S.S. 304 | S.S. 316 | |||
| ELEMENT | S.S. 316 L | S.S. 316 L | S.S. 316 L | S.S. 316 L | S.S. 316 L | |||
FOR FLAME IN LINE ARRESTOR
| SIZE | 2” | 3” | 4” | 6” | 8” | 10” | 12” | |
| DN | 50 | 80 | 100 | 150 | 200 | 250 | 300 | |
| A | 233 | 260 | 270 | 335 | 360 | 380 | 470 | |
| B | 220 | 250 | 287 | 450 | 550 | 610 | 850 | |
FOR FLAME END OF LINE ARRESTOR
| SIZE | 2” | 3” | 4” | 6” | 8” | 10” | 12” | |
| DN | 50 | 80 | 100 | 150 | 200 | 250 | 300 | |
| C | 230 | 283 | 283 | 410 | 500 | 650 | 750 | |
| D | 210 | 235 | 240 | 290 | 340 | 360 | 400 | |
| TYPE / FLOW | FLAME ARRESTER NM3/H X 1000 AIR | |||||||
| DIA | 50 (2”) | 80 (3”) | 100 (4”) | 150 (6”) | 200 (8”) | 250 (10”) | 300 (12”) | |
| DIFF. PRESS mb(p) | ||||||||
| 3 | 0.09 | 0.18 | 0.28 | 1.02 | 1.32 | 1.75 | 3.14 | |
| 4 | 0.10 | 0.20 | 0.31 | 1.13 | 1.45 | 1.93 | 3.45 | |
| 5 | 0.11 | 0.22 | 0.34 | 1.24 | 1.60 | 2.12 | 3.80 | |
| 10 | 0.15 | .30 | .48 | 1.73 | 2.23 | 2.96 | 5.32 | |
| 15 | 0.18 | 0.37 | 0.57 | 2.07 | 2.68 | 3.56 | 6.38 | |
| 20 | 0.21 | 0.43 | 0.67 | 2.43 | 3.14 | 4.16 | 7.47 | |
| 25 | 0.25 | 0.49 | 0.77 | 2.80 | 3.61 | 4.79 | 8.59 | |
| 30 | 0.27 | 0.53 | 0.83 | 3.02 | 3.89 | 5.17 | 9.28 | |
| 35 | 0.28 | 0.56 | 0.87 | 3.17 | 4.09 | 5.43 | 9.74 | |