Flashback arrestors and check valves are safety devices designed for oxy-fuel systems to prevent or control damage from an occurrence like a flashback. They are used to prevent damage to equipment, but more importantly, to prevent personal injury. By now you probably have read the Safety Guidelines and you already know what safety devices are available and their features, etc. The intent of this article is to discuss the proper selection, and recommended placement and maintenance of these safety devices. This additional information will help you to maximize the benefits of using flashback arrestors and other safety devices.

Selection:Choose the proper size device, paying particular attention to required equipment gas flow rates and the flow information supplied with the flashback arrestors like P charts. Features like thermal shut offs may also influence device selection. The aggregate number of safety devices in a system can also create an issue. Each safety device used creates a restriction in flow, so always follow the equipment manufacturer’s recommendations. Check valves alone create little restriction; however, as little as one extra flashback arrestor may render the system unsafe to operate.

Flashback arrestors on a Harris torch


The best place to install the equipment for the most protection is as close to the designed or potential problem area as conditions permit. Sometimes physical size and inherent flow restrictions limit the placement, so check with the equipment manufacturer for suggestions as to the placement and or combination that will provide the most personal protection and expose the equipment to the least potential damage in case of an incident.

Maintenance and Testing:

All equipment, especially safety equipment like flashback arrestors and check valves, must be in good working order to function properly. Check with the manufacturer for suggestions regarding periodic testing and maintenance. In the absence of the specific manufacturer’s instructions, a general rule would be to check the safety devices every 6 months when used in average conditions, more often in abusive and/or extremely dirty environments.

Check valves alone or those incorporated in most flashback arrestors are generally easy to test. Contact The Harris Product Group for a copy of the instructions. Flashback arrestors with flame barrier devices are to be tested only by methods and or equipment recommended by the manufacturer – if at all.

Never try to repair check valves or flashback arrestors unless authorized by the manufacturer – replace when found defective.

Select the device with the features providing the most protection given the specific conditions, application, and environment the equipment will be used in. Place safety device(s) within the system at the location that provides the most protection for both the operator and the equipment without creating additional hazards or issues that may discourage their continued use. Once chosen and installed, maintain the safety equipment by not exposing it to excessively dirty conditions or abuse. Test or inspect the equipment according to the manufacturer’s recommendations. Harris recommends testing and/or inspection periods every 6 months for average conditions and more often in abusive or extreme conditions.