Flash Back Arresters

About Flash Back Arresters

Flash back arresters are critical safety devices designed to prevent dangerous reverse gas flow and flame propagation in oxy-fuel gas welding, cutting, and heating equipment. These essential protective devices are fitted between the gas supply (cylinder or manifold) and the hoses or equipment, acting as a one-way valve that stops flames from travelling back up the gas line towards the cylinder. In the event of a flashback - where flames travel back through the torch or hoses - these arresters quickly shut off the gas flow and extinguish the flame, preventing potentially catastrophic explosions or cylinder damage.

Our range of flash back arresters includes models specifically designed for different gas types, including oxygen and fuel gases such as acetylene, propane, and LPG. Available from trusted brands including Draper and Sealey, these arresters comply with relevant British and European safety standards (BS EN ISO 5175), ensuring reliable protection for professional tradespeople and serious DIY enthusiasts. Flash back arresters typically feature robust brass construction with sintered flame arrestor elements that can withstand the extreme conditions of a flashback event whilst maintaining uninterrupted gas flow during normal operation.

Whether you're a professional welder working on site or in a fabrication workshop, or a metalworker using oxy-fuel equipment for cutting and heating applications, installing appropriate flash back arresters on both oxygen and fuel gas lines is not just good practice - it's an essential safety requirement mandated by HSE guidelines and workshop insurance policies throughout the UK.

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• Flashback: A dangerous condition where flames travel backwards through the torch, hoses, or regulator towards the gas cylinder, potentially causing an explosion. Flashbacks can be caused by incorrect gas pressures, overheating, or blockages in the torch tip.
• Sintered Filter: A porous metal element created by compressing and heating metal particles until they bond together. This filter acts as a flame barrier whilst allowing gas to pass through, and is the key component that stops flame propagation in a flash back arrestor.
• Non-Return Valve: A one-way valve mechanism within the arrestor that prevents reverse gas flow, stopping oxygen from entering fuel gas lines (or vice versa) which could create explosive mixtures inside hoses or regulators.
• Thermal Cut-Off: A temperature-sensitive component that automatically shuts off gas flow if excessive heat from a sustained flashback is detected, providing an additional layer of protection beyond the flame barrier.
• Inline Arrestor: A flash back arrestor installed in the hose line between the regulator and torch, as opposed to regulator-mounted arrestors. Inline models provide protection closer to the point of use.
• BS EN ISO 5175: The British and European safety standard that specifies requirements and testing procedures for flash back arrestors used with oxy-fuel gas welding and cutting equipment.

Who Uses Flash Back Arresters?

• Welders and Fabricators: Professional welders working with oxy-acetylene equipment in workshops, factories, and on-site construction projects
• Metal Workers and Blacksmiths: Tradespeople using gas torches for heating, forming, and joining metal components
• Plumbers and Heating Engineers: Professionals using oxy-fuel equipment for pipe cutting, brazing, and soldering applications
• Agricultural and Plant Engineers: Maintenance engineers working on farms and industrial sites where gas cutting and welding equipment is used for repairs
• Vehicle Restoration Specialists: Classic car restorers and body shop professionals using gas welding and cutting equipment
• Automotive Workshops: Mechanics and fabricators working on exhaust systems, chassis repairs, and custom modifications
• Sculptors and Artists: Metal artists and sculptors using oxy-fuel equipment for creative metalwork
• Demolition and Salvage Contractors: Professionals using cutting torches for dismantling metal structures and equipment
• Maintenance Departments: In-house maintenance teams in manufacturing, utilities, and facilities management who maintain welding equipment

How to Choose the Right Flash Back Arresters

Gas Type Compatibility: The most critical consideration is selecting arrestors specifically designed for the gas you're using. Oxygen flash back arrestors must only be used on oxygen lines, whilst fuel gas arrestors (acetylene, propane, LPG) must be matched to your specific fuel type. Never interchange these as they have different specifications and safety characteristics. For complete protection, you'll need arrestors for both your oxygen and fuel gas lines.

Installation Location: Flash back arrestors can be fitted at the regulator outlet (immediately after the cylinder regulator) or inline within the hose system. Many professionals install arrestors at both locations for maximum protection - regulator-mounted arrestors protect the cylinder and regulator, whilst torch-mounted or inline arrestors provide additional protection closer to the point of use. Check the thread sizes and connections to ensure compatibility with your existing equipment.

Standards Compliance: Only purchase flash back arrestors that comply with BS EN ISO 5175 standards. This ensures the device has been properly tested and certified for use in the UK. Reputable brands like Draper and Sealey manufacture their arrestors to meet these stringent safety requirements, giving you confidence in their protective capabilities.

Flow Rate and Pressure Rating: Ensure the flash back arrestor can handle the gas flow rates and pressures required for your specific applications. Higher capacity torches and cutting equipment may require arrestors with greater flow capacity to avoid restricting gas supply during operation. Check the manufacturer's specifications against your equipment requirements.

Build Quality and Maintenance: Look for robust brass construction with replaceable or serviceable components. Quality flash back arrestors should have clear visual indicators (often a red flag or button) that pop up when activated, alerting you that a flashback has occurred and the device needs attention. Consider whether replacement parts are readily available and whether the manufacturer provides clear maintenance guidance.

Popular Accessories

• Welding and Cutting Hoses: High-quality twin hoses specifically designed for oxy-fuel applications, available in various lengths
• Gas Regulators: Oxygen and acetylene regulators with accurate pressure gauges for precise gas control
• Torch Sets: Complete welding and cutting torch assemblies with interchangeable nozzles for different applications
• Hose Clips and Protectors: Securing devices and protective sleeves to prevent hose damage and ensure safe connections
• Cutting and Welding Nozzles: Replacement tips in various sizes for different material thicknesses and applications
• Striker Lighters: Spark-generating lighters designed specifically for safely igniting gas torches
• Cylinder Trolleys: Mobile storage and transport solutions for gas cylinders used on site or in workshops
• Welding Goggles and Face Shields: Essential PPE with appropriate shade ratings for oxy-fuel work
• Heat-Resistant Gloves: Protective welding gauntlets for handling hot materials and torches
• Leak Detection Fluid: Specialist solutions for checking gas connections and identifying potential leaks

Safety Information

Flash back arresters are mandatory safety equipment when using oxy-fuel gas welding and cutting equipment, and their installation is strongly recommended by the Health and Safety Executive (HSE). Under the Pressure Systems Safety Regulations and general workplace safety duties, employers must ensure gas equipment is properly protected against flashback hazards. Even for DIY users, installing flash back arresters is essential - gas cylinder suppliers and insurance companies may refuse coverage if equipment isn't properly protected.

Installation Requirements: Always install flash back arresters on both oxygen and fuel gas lines. Fit them according to the manufacturer's instructions, ensuring threads are clean and connections are gas-tight. Use appropriate spanners - never overtighten as this can damage sealing faces. After installation, conduct a leak test using approved leak detection fluid, never soapy water which can freeze or cause corrosion.

Regular Inspection and Maintenance: Check flash back arresters before each use for any signs of damage, corrosion, or previous activation (indicated by a popped-up red flag or button on many models). If an arrestor has been activated during a flashback event, it must be inspected, serviced, or replaced according to the manufacturer's guidance - never simply reset and continue using without proper checks. Keep arrestors clean and free from oil, grease, and contamination.

Understanding Limitations: Whilst flash back arresters provide crucial protection, they are one component of a comprehensive safety system. Always maintain correct working pressures, use properly maintained equipment, ensure adequate ventilation, keep torches and nozzles clean, and follow proper lighting and shutdown procedures. Regular training in oxy-fuel equipment use and flashback prevention is essential for all operators.

Emergency Procedures: If a flashback occurs, immediately close the torch valves (fuel gas first, then oxygen), then close the cylinder valves. Allow the equipment to cool before inspection. Check that flash back arresters have operated correctly and investigate the cause of the flashback before resuming work. Common causes include blocked nozzles, incorrect pressures, or overheating from prolonged use.

Frequently Asked Questions

Do I really need flash back arresters on both gas lines?

Yes, absolutely. Both oxygen and fuel gas lines require their own specific flash back arresters. A flashback can occur on either line, and each gas type requires an arrestor designed for its particular properties and pressures. Installing arrestors on both lines provides comprehensive protection for your equipment and, more importantly, for you. This dual protection is considered best practice by the HSE and is required by most workplace safety policies and insurance providers.

How do I know if a flash back arrestor has been activated?

Most modern flash back arresters feature a visual indicator - typically a red flag or button that pops up when the device has been triggered by a flashback event. You may also notice that gas flow has stopped or is significantly restricted. If your arrestor has been activated, you must not simply reset it and carry on working. The device should be inspected according to the manufacturer's instructions, and you should investigate what caused the flashback before resuming work.

Can flash back arresters be serviced or do they need replacing after activation?

This depends on the specific model and manufacturer. Some flash back arresters are designed to be serviceable with replaceable filter elements and seals, whilst others are sealed units that require complete replacement after activation. Quality brands like Draper and Sealey provide clear guidance in their documentation. Even serviceable models should be professionally inspected after a flashback event to ensure all components remain in safe working condition.

Where should flash back arresters be installed - at the regulator or torch end?

For optimal protection, many professionals install flash back arresters at both locations. Regulator-mounted arrestors (fitted immediately after the cylinder regulator) protect the cylinder and regulator assembly, whilst torch-mounted or inline arrestors provide additional protection closer to the point of use. At minimum, arrestors should be fitted at the regulator end, but the dual-location approach offers the highest level of safety, particularly in professional or high-use environments.

Are all flash back arresters the same or do different gases need different types?

Different gases absolutely require different flash back arresters. Oxygen arrestors are specifically designed for oxygen service with materials and specifications suited to high-pressure oxygen environments. Fuel gas arrestors for acetylene, propane, or LPG have different internal components and pressure ratings appropriate to those gases. Never use an oxygen arrestor on a fuel line or vice versa - they are not interchangeable and using the wrong type compromises your safety and invalidates the device's certification.