FOR RAILWAY applications such as engine compartments and equipment cubicles, Brush Traction is distributing Pyrogen, a fire suppressant derived from solid fuel developed for the Russian space programme. When activated by an electrical signal or a pyrotechnic fuse, the Pyrogen canister produces an aerosol of potassium carbonates in carbon dioxide, nitrogen and water vapour which extinguishes the fire by removing the flame chain carriers of oxygen and hydrogen, and by absorbing heat.

Trials at Brush have included a simulated engine room fire in a Class 47 locomotive, where a 0·5m2 tray of diesel fuel on water and a spray representing a broken fuel line were ignited, generating a temperature of 560í C. Eight Pyrogen MAG-4 canisters, each weighing 4·5 kg and measuring 350mm long and 95mm in diameter, extinguished the fire within 15sec. A reserve battery of eight canisters had also been installed.

As demonstrated by this test where an access door and other openings were left unclosed, Pyrogen is effective in areas other than sealed enclosures. It has a low toxicity and has been certified as having zero ozone-depletion potential by the US Environmental Protection Agency. In addition to their compact size and low weight, the self-contained Pyrogen canisters are unpressurised, requiring little maintenance. They are simply replaced once discharged.

Brush Traction, Great Britain

Reader Enquiry Number 139