Why Can't a Flame Arrester Operate Alone?

A Flame Arrester Only Prevents Flame Propagation

The primary function of a Flame Arrester is to extinguish flames and prevent flame flashback from traveling back into storage tanks or process piping.

However, it does not:

• Regulate system pressure
• Relieve excessive pressure
• Admit air during vacuum conditions
• Control flow rate
• Prevent reverse flow

Therefore, installing only a Flame Arrester does not protect a system from overpressure, vacuum collapse, or reverse flow hazards.

Industrial Safety Requires Multiple Layers of Protection

Modern industrial facilities are designed according to the Layer of Protection (LOPA) principle, where each safety device performs a specific function.

Typical responsibilities include:

• Flame Arrester – Prevents flame propagation
• Breather Valve – Controls tank pressure
• Emergency Vent Valve – Provides emergency pressure relief
• Check Valve – Prevents reverse flow

Only when these devices work together can a storage system achieve maximum operational safety.

Breather Valve – The Most Common Companion Device

What Is a Breather Valve?

A Breather Valve, also known as a Pressure Vacuum Relief Valve (PVRV), maintains safe pressure conditions inside a storage tank by:

• Releasing excessive internal pressure
• Admitting air during vacuum conditions
• Protecting tanks from deformation or structural failure

It is considered essential for petroleum, chemical, and solvent storage tanks.

Why Is It Installed with a Flame Arrester?

Whenever a Breather Valve allows vapor to exit or air to enter a tank, the vent opening becomes the most vulnerable point for flame intrusion.

Installing a Flame Arrester together with the Breather Valve provides several benefits:

• Prevents external flames from entering the storage tank
• Protects personnel and equipment during fire incidents
• Meets the requirements of API 2000 and ISO 16852

This is the most common configuration used in fuel storage facilities.

Emergency Vent Valve

When Is an Emergency Vent Required?

An Emergency Vent Valve is designed to protect storage tanks during abnormal operating conditions, such as:

• External fire exposure
• Sudden pressure increase
• Excessive temperature rise
• Situations where the Breather Valve cannot discharge sufficient flow

It rapidly releases pressure to prevent catastrophic tank failure.

How Is It Different from a Flame Arrester?

Although often confused, these two devices serve completely different purposes.

Flame Arrester

• Stops flame propagation

Emergency Vent Valve

• Relieves excessive pressure

One cannot replace the other.

Check Valve

Function

A Check Valve allows fluid or gas to flow in only one direction.

Whenever reverse flow occurs, the valve automatically closes.

Why Combine It with a Flame Arrester?

In systems handling:

• LPG
• Natural Gas
• Hydrogen
• Biogas
• Industrial gases

Combining a Check Valve with a Flame Arrester provides dual protection by:

• Preventing reverse flow
• Preventing flame flashback
• Protecting upstream equipment

This combination is widely used in industrial gas piping systems.

Vent Lines and Vent Piping

What Is a Vent Line?

A Vent Line is a pipeline that releases vapor from a storage tank either to the atmosphere or to a vapor recovery system.

Because it is directly exposed to the surrounding environment, it is one of the highest-risk locations for:

• External ignition sources
• Sparks
• Flame propagation

Where Is a Flame Arrester Installed?

A Flame Arrester is typically installed:

• At the end of the vent line
• On atmospheric vent outlets
• On vapor discharge piping
• Upstream of VOC recovery systems

This location ensures that any external flame is extinguished before entering the storage system.

Typical Installation Configurations

Petroleum Storage Tanks

A typical storage tank safety system includes:

• Breather Valve
• Flame Arrester
• Emergency Vent Valve

This arrangement provides pressure regulation, fire protection, and emergency pressure relief.

LPG and Industrial Gas Systems

Typical components include:

• Flame Arrester
• Check Valve
• Pressure Relief Valve

These devices work together to prevent flame propagation and reverse gas flow.

VOC Recovery Systems

A standard VOC recovery installation often includes:

• Pilot Operated Breather Valve
• Flame Arrester
• Vapor Recovery Piping
• VOC Treatment System

This configuration minimizes product loss while improving environmental protection.

Welding and Cutting Systems

Flashback arrestors commonly integrate:

• Flame Arrester
• Check Valve
• Thermal Shut-Off Valve
• Automatic Safety Shut-Off Mechanism

These integrated devices protect gas cylinders and hoses from flashback.

Common Mistakes When Selecting Safety Equipment

Installing Only a Flame Arrester

This is one of the most common mistakes.

Without additional protection:

• No Breather Valve → Tank may experience overpressure or vacuum collapse
• No Emergency Vent → Increased risk of tank rupture during fire
• No Check Valve → Reverse flow remains possible

A Flame Arrester alone cannot provide complete system protection.

Incorrect Installation Location

Even the correct equipment can become ineffective if installed improperly.

Common installation errors include:

• Flame Arrester not installed at the vent outlet
• Check Valve installed in the wrong flow direction
• Incorrect installation distance from the protected equipment
• Failure to periodically inspect and clean the flame element

Proper installation and maintenance are just as important as equipment selection.

Conclusion

A Flame Arrester is one of the most important safety devices in storage tank and process systems, but it is only one component of a complete protection strategy.

An effective safety system should integrate:

• Breather Valves
• Emergency Vent Valves
• Check Valves
• Pressure Relief Valves
• Proper Vent and Vapor Recovery Systems

Selecting the appropriate equipment, installing it correctly, and complying with standards such as API 2000, ISO 16852, and NFPA 30 are essential for minimizing fire hazards, product losses, environmental emissions, and equipment damage.

Frequently Asked Questions (FAQs)

1. Should a Flame Arrester always be installed with a Breather Valve?

Yes. In most petroleum, chemical, and solvent storage tanks, a Flame Arrester is installed together with a Breather Valve to provide both pressure control and flame protection.

2. Is an Emergency Vent Valve mandatory?

For large storage tanks or systems containing flammable products, an Emergency Vent Valve is highly recommended and is often required by applicable engineering standards.

3. Can a Check Valve replace a Flame Arrester?

No. A Check Valve prevents reverse flow, while a Flame Arrester prevents flame propagation. Their functions are entirely different and complementary.

4. Where should a Flame Arrester be installed?

It is typically installed at the end of a vent line, on atmospheric vent outlets, or on vapor piping to prevent flames from entering storage tanks or process systems.

5. Can a single safety device fully protect a storage tank?

No. A safe storage system requires multiple layers of protection, combining Flame Arresters with Breather Valves, Emergency Vent Valves, Check Valves, and other safety devices to ensure comprehensive protection.