Flame arresting elements
In long uninterrupted lengths of pipe, flames can easily reach very high velocities – typically 2000 m/s for town gas-air mixtures. Correspondently, shorter lengths of pipe produce flames of lower velocity. In addition, gas type used for the flames also affects the flames’ velocity. The lower hydrocarbons (e.g. methane, butane), have a lower velocity than hydrogen or acetylene. Recemat metalfoam type NC-2733.13 has been shown to be capable of arresting flames in pipes containing ethylene-air mixtures, reaching velocities up to 550 m/s. It has proved, grade NC-4753 is capable of arresting hydrogen-oxygen flames where the initial gas pressure was 2.75 bar-g.
Furthermore, Recemat metalfoam can be used as a flame arrester. Long lengths of pipe that contain pre-mixed gas, are protected near to possible sources of ignition such as fan outlets, pumps and valves . This ensures that if ignition does occur, the flame does not have enough length of pipe to accelerate to high velocities. In these cases, metal foam type NC-2733.10 is the standard arrester material for gases other than hydrogen or acetylene. For low order hydrocarbons, metal foam type NC-1116.20 can be used as an arrester. Other applications for metal foam type NC-1116.20 are:
- Protection of pipelines carrying premixed flammable gas.
- Protection of duct systems, marine tankers etc.
- Protection of solvent recovery plants.
- Protection of fuel tanks of aircraft.
- Protection of gas detectors.
- Fuel lines for gas fired appliances.
- Weldingtorch feed lines.
- Venting of underground tanks.
Because of this wide range of applications and the many possible compositions of (mixed) gases and vapours, Recemat is not able to provide formal certificates or specified test-reports, along with the delivery of its flame arresting elements.