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What is a Flame Arrester and How Does it Work?
- 4 days ago
- 7 min read
If you work in a chemical plant, petroleum storage terminal, pharmaceutical facility or distillery, you have almost certainly seen a flame arrester installed on a storage tank or pipeline — even if you did not know what it was called. It is one of the most important passive safety devices in any facility that handles flammable liquids or gases, yet it is one of the least understood.
This guide explains what a flame arrester is, how it works, what types are available, where they are required and how to choose the right one for your application.
What is a Flame Arrester?
A flame arrester — also written as flame arrestor — is a passive safety device designed to allow the free flow of gas or vapour through a pipeline or vent while completely stopping the transmission of flame. It does this without any moving parts, without any external power supply and without any operator intervention.
In simple terms: gas flows through freely, flame cannot pass through.
Flame arresters are installed on storage tank vents, process pipelines, vent headers and equipment handling flammable vapours to prevent a flame from travelling from one side of the device to the other. Without a flame arrester in the correct location, a single ignition event — a spark, a lightning strike, static discharge or an open flame near a vent — can travel back through the vapour path and cause a catastrophic explosion inside a storage tank or process vessel.
How Does a Flame Arrester Work?
The working principle of a flame arrester is based on heat absorption and flame quenching. Inside every flame arrester is a flame element — a matrix of very narrow channels, most commonly made from stainless steel crimped ribbon wound into a compact disc or cylinder shape.
When a flame front enters the flame element, it is forced to travel through thousands of these tiny channels simultaneously. The channels are engineered to be narrower than the quenching diameter of the flammable gas — this is the critical dimension below which a flame simply cannot sustain itself. As the flame enters each narrow channel, the heat energy of the flame is absorbed by the stainless steel element walls faster than the flame can generate new heat. The flame cools below its ignition temperature and is extinguished — quenched — before it can pass through to the other side.
The gas itself continues to flow through the same channels without restriction. Only the flame is stopped.
This is why flame arresters require no power, no control signal and no moving parts — the physics of heat transfer do all the work passively and continuously.
Key Components of a Flame Arrester
Understanding the parts of a flame arrester helps when specifying or maintaining one.
The flame element is the heart of the device. It is the stainless steel crimped ribbon matrix through which all gas flow passes. The element is the component that actually quenches the flame. It must be kept clean and free of blockage at all times — a fouled or blocked element provides zero protection.
The body or housing is the outer shell that contains the element and connects to the pipeline or vent nozzle. Bodies are available in cast aluminium, carbon steel, stainless steel SS 304 and SS 316 depending on the service conditions and the fluid being handled. Cast aluminium is the most common for atmospheric tank vent applications because it is lightweight and corrosion resistant in most environments. Carbon steel and stainless steel are used for higher pressure pipeline applications and corrosive service.
The end connections are the flanged or screwed connections that attach the flame arrester to the pipeline or tank nozzle. Standard connections include ANSI 150#, ANSI 300#, BS, DIN flanged and BSP/NPT screwed ends. The connection standard must match your pipeline or nozzle specification exactly.
The inspection and drain ports are optional features on larger pipeline flame arresters that allow the element condition to be checked and the body to be drained without removing the unit from the line.
Types of Flame Arresters
Not all flame arresters are the same. The type you need depends on where it is installed, the length of pipeline between the ignition source and the arrester, and the nature of the flame event it needs to stop. There are four main types used in industrial applications in India.
End-of-line flame arresters are installed at the open end of a vent pipe or storage tank vent nozzle. They face the atmosphere directly. Their job is to stop an atmospheric flame — from an external ignition source such as a spark or open flame near the vent — from entering the tank through the vent opening. End-of-line flame arresters are the most commonly used type and are found on the vast majority of fixed roof storage tanks handling flammable liquids. They are designed for deflagration protection — stopping subsonic flame events.
Inline flame arresters are installed within a pipeline between two points in a process system. Unlike end-of-line types, inline arresters must handle continuous process flow in both directions and withstand operating pressure. They are used where flame must be stopped mid-pipeline — for example between a process vessel and a flare header, or in a vapour recovery system. Inline arresters are designed for bidirectional flame protection and are available in both deflagration and detonation rated configurations.
Deflagration flame arresters stop subsonic flame propagation — where the flame front travels slower than the speed of sound. The majority of flame events in chemical plants and storage facilities are deflagrations. End-of-line arresters are always deflagration type. Short inline runs close to the ignition source are also deflagration type.
Detonation flame arresters stop supersonic flame propagation — where the flame front has accelerated to greater than the speed of sound, producing a powerful pressure shock wave known as a detonation. This can happen in longer pipelines where a deflagration accelerates through the DDT process — Defla
gration to Detonation Transition. Detonation arresters are required on pipeline runs longer than approximately 3 metres between the ignition source and the arrester, and on fuel gas distribution systems. They have a more complex narrow-channel element design and a heavier-duty body to withstand the shock pressure of a detonation event.
Where Are Flame Arresters Required?
Flame arresters are required by process safety standards and statutory regulations in any location where flammable vapours are vented to atmosphere or transported through pipelines. In India, the Petroleum Act, the Factories Act and PESO (Petroleum and Explosives Safety Organisation) regulations require flame arresters on petroleum storage tanks. International standards including API 2000, EN 12874 and ISO 16852 define where and how flame arresters must be installed.
In practice, flame arresters are required on the following installations.
Storage tank vent nozzles on any tank storing flammable liquids — crude oil, petrol, diesel, naphtha, solvents, alcohol and chemical intermediates all require flame-arrested tank vents. A breather valve alone is not sufficient — the breather valve controls the pressure and vacuum but the flame arrester prevents ignition of the escaping vapour.
Pipeline vents and vent headers on process systems carrying flammable vapours — including distillation column vents, reactor vessel vents, vapour recovery lines and flare headers.
Loading and unloading gantries at petroleum terminals and chemical plants where tanker loading creates vapour displacement that must be vented safely.
Biogas and landfill gas pipelines where the fuel gas is transported over long distances and detonation risk must be controlled.
Fuel gas distribution systems at industrial facilities, power plants and refineries where natural gas or LPG is piped to burners and furnaces.
How to Choose the Right Flame Arrester
Selecting the correct flame arrester requires answering four questions.
Where is it installed — end of line or inline? If it is on a tank vent nozzle open to atmosphere, you need an end-of-line type. If it is mounted within a pipeline between two connected points, you need an inline type.
How long is the pipeline between the ignition source and the arrester? For runs under 3 metres, a deflagration-rated arrester is generally sufficient. For runs over 3 metres, always specify a detonation-rated device because DDT is possible in longer runs.
What is the gas or vapour group? Flammable gases and vapours are classified into groups based on their ignition properties. Group IIA includes propane, butane, hexane and most petroleum vapours. Group IIB includes ethylene, ethanol and many chemical solvents. Group IIC includes hydrogen, acetylene and carbon disulphide — the most difficult to arrest, requiring specially designed elements. You must specify the correct gas group when ordering a flame arrester.
What size and connection is required? Match the flame arrester size to the pipeline or vent nozzle size. Standard sizes range from 1 inch (DN25) to 12 inch (DN300) for most industrial applications. The end connection — ANSI, BS, DIN flanged or screwed — must match your existing pipeline or tank nozzle exactly.
Flame Arrester Maintenance — What You Must Know
A flame arrester is a passive device but it is not a fit-and-forget device. The stainless steel element can become blocked over time due to product polymerisation, dust, ice formation in cold climates or liquid carryover from the process. A blocked flame arrester allows no gas flow and provides no flame protection — it is effectively useless and dangerous.
Flame arresters should be inspected at least once every 12 months in clean service and every 3 to 6 months in dirty or fouling service. During inspection the element should be removed, visually checked for blockage, corrosion or mechanical damage, cleaned with compressed air or a compatible solvent wash, and reinstalled securely. Any element that is damaged, corroded through or cannot be cleaned to free flow condition should be replaced immediately.
Always keep a spare element in stock for your critical flame arresters. A storage tank without a functioning flame arrester on its vent is a serious process safety violation.
Summary
A flame arrester is a simple, reliable, passive safety device that prevents flame from travelling through a pipeline or vent by quenching the flame front in a matrix of narrow stainless steel channels. It requires no power, no moving parts and no operator action. It works continuously and silently every day.
Selecting the right type — end-of-line or inline, deflagration or detonation rated — depends on the installation location, pipeline length and gas group. Regular annual inspection and element cleaning is essential to maintain protection.
Flow Industries manufactures a complete range of flame arresters in Ankleshwar, GIDC, Gujarat, India — including end-of-line, inline, detonation and deflagration types in sizes 1" to 12". ISO 9001:2015 certified with over 20 years of manufacturing experience. Trusted by Sun Pharma, Pidilite, GFL, Navin Fluorine, Hindalco and 100+ leading industries across Gujarat and India.
📞 +91 98244 66603 / +91 98245 66603 📍 Plot No. 115, Yogi Industrial Estate, GIDC, Ankleshwar — 393002, Dist. Bharuch, Gujarat
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