Fire Damper

What Are Flashback Arrestors and Fire Dampers?

In many gas systems and welding/cutting applications, flashback arrestors and fire dampers are often considered similar devices. However, in reality, they differ significantly in operating mechanisms and purposes. Understanding each device clearly helps you select the correct solution and ensure maximum safety for gas supply or welding systems.

What Is a Flashback Arrestor According to Technical Standards?

A Flashback Arrestor is a mechanical safety device installed in flammable gas pipelines. Its primary function is to prevent flames from traveling backward toward the gas source (gas cylinders, gas stations, or supply manifolds), thereby avoiding serious fire or explosion hazards.

Flashback arrestors operate based on three main mechanisms:

• Cutting off gas flow when temperature exceeds a safe threshold

• Rapid pressure drop to extinguish the flame

• Cooling the flame through internal metallic structures

International standards such as ISO 5175-1, EN 730, and ISO 10294 require flashback arrestors to:

• Stop flames instantly

• Withstand reverse pressure of ≥16 bar

• Operate reliably in high-temperature environments

Example: In metallurgical plants using oxygen–acetylene systems, the absence of flashback arrestors can allow flames to travel back into gas cylinders, potentially causing catastrophic explosions that endanger personnel and equipment.

What Is a Fire Damper and Its Role in Gas Systems?

A Fire Damper (Flame Arrestor) is a passive safety device installed in pipelines, vents, or tank inlets/outlets to prevent flame propagation along the direction of gas flow.

Unlike flashback arrestors—which mainly stop reverse flames—fire dampers can be designed to block flames in one or both directions, depending on installation location and gas characteristics.

Main components include:

• Metal discs or stainless-steel mesh cores for flame cooling

• High-temperature and pressure-resistant housing

• No fusible link or check valve (for standard types)

Common applications:

• Fuel storage tanks

• Flammable gas pipelines and chemical processing systems

• Ventilation and venting systems in hazardous areas

Key advantage: Fire dampers require no control system or power supply. They work purely mechanically and are highly effective in chemical and high-pressure gas environments.

Difference Between FD and MFD Fire Dampers

Both FD (Flame Arrestor Disk) and MFD (Multi-Function Flame Arrestor Disk) are variants of fire dampers, but they differ in performance and safety levels.

For simple residential or manual welding systems, FD models are usually sufficient. In industrial environments requiring high safety, MFD is mandatory.

When Should You Choose FD Instead of MFD?

FD is suitable when:

• The system is simple with low flashback risk

• Budget optimization is required

• Continuous operational supervision is available

MFD is recommended when:

• Operating in explosive or hazardous environments (chemical rooms, medical gas systems, industrial gas)

• The system is automated with no constant supervision

• Strict fire safety acceptance and inspection are required

QC06 and ISO Standards for Flashback Arrestors

Safety devices must be evaluated based on certified standards, not appearance or branding. In fire protection and gas systems, QC06, ISO 10294, and EI ratings define real protection levels.

Significance of QC06 in Fire Protection

QC06 is a Vietnamese fire safety certification standard for flame arrestors and flashback prevention devices, issued by the Fire Prevention Authority and effective since 2020.

According to QC06, flashback arrestors must:

• Withstand pressure ≥16 bar

• Block flames in both gas directions, with no leakage after 10 minutes of testing

• Maintain structural integrity at temperatures up to 110°C

QC06 applies to equipment used in:

• High-rise buildings (gas stations, technical floors)

• Industrial welding workshops and chemical plants

• Medical gas and specialty gas systems

Devices without QC06 certification may be rejected during fire safety acceptance inspections.

EI Rating and ISO 10294 in Fire Damper Testing

High-grade flashback arrestors such as FD-MFD QC06 must also comply with ISO 10294, which evaluates flame propagation resistance.

• E (Integrity): Prevents flame penetration

• I (Insulation): Limits heat transfer

Example:

• EI120 rating means the valve can block flames and maintain safe temperatures for 120 minutes

• Some FD-MFD models achieve EI180, suitable for oil refineries, clean rooms, and laboratories

Combining QC06 (Vietnam) and ISO (international) standards ensures full reliability in all emergency scenarios.

Practical Applications of FD-MFD Flashback Arrestors

Flashback arrestors are widely used not only in heavy industry but also in civil and medical systems.

Gas welding and cutting systems

Common risks include:

• Blocked torch tips

• Uneven gas pressure

• Incorrect operating procedures

Installing flashback arrestors:

• Prevents flame return into gas cylinders

• Protects operators and equipment

• Reduces explosion risks

Recommendation: Use MFD models with sensors for semi-automatic or CNC welding systems.

Industrial and residential gas systems

Installed at:

• Pressure regulating stations

• Near burners or heat-generating equipment

• Junction points between gas pipelines

Especially critical in enclosed kitchens or industrial cooking areas where gas leaks and flashback may occur silently.

Oxygen–gas systems and gas-specific selection

Each gas requires a specialized arrestor:

• Oxygen: Oil-free, oxidation-resistant materials

• Hydrogen: High-pressure, fast-response thermal resistance

• Acid gases & CO₂: Corrosion-resistant stainless steel or coated bodies

Some FD-MFD models integrate impurity filters to protect pipelines and reduce wear.

Comparing FD-MFD QC06 with Conventional Valves

FD-MFD QC06 valves are typically supplied with factory inspection certificates and authenticity labels for traceability.

What Makes Automatic Flashback Arrestors Different?

Automatic MFD models offer advanced safety features:

• Automatic shut-off during reverse flow

• Integration with alarm sensors and automatic gas cut-off

• Ideal for unattended systems (production lines, laboratories)

Their cost is typically 1.5–2 times higher than standard FD models, but safety performance is significantly enhanced.

Conclusion

Flashback arrestors are not optional accessories—they are critical safety components for protecting people and assets in high-risk environments. With FD-MFD QC06 models, users gain reliable flame blocking, long service life, and full compliance with fire safety standards. Selecting and installing the correct valve is an investment in long-term, sustainable safety for the entire system.