"Sludge"!


Photo: Angus Davis


In the days of steam, treatment of water for locomotives was important to reduce scaling, corrosion and the need for excessive locomotive maintenance. This helped to reduce costs and maximise performance. Regular boiler washouts of cooling locomotives with hot water took time and reduced motive power availability: cold water washouts took even longer. Both involved removal of washout plugs, handhole and mudhole doors for inspection purposes. Across Great Britain there were great variations in the quality of water available to locomotive depots and watering points. Locomotive depots, particularly in hard water areas, had their own water softening plants which treated water using lime-soda ash. The softening process resulted in a semi-liquid whitish “sludge” which needed to be collected, removed and dumped. Some sludge was hardened and taken away as solid matter. But old tenders were converted and pressed into service as sludge carriers and were seen at motive power depots where softening took place. The sludge tanks pictured here are believed to be derived from the tenders of Robinson-designed 2-8-0 locomotives built for the Railway Operating Division in 1917 and 1918 based on an earlier Great Central Railway design. After the Great War, many of these locomotive were bought and used by three of the “Big Four” companies. The first is seen at Southall MPD (81C) and the second at Bath Green Park MPD (82F), both of which had softening plants. Sodium and tannin substances also played a part in improving water quality and in later years briquettes or liquid chemicals were put into locomotive tenders and tanks. In addition, the blowdown valve on locomotives drained small quantities of water and harmful salts into the ashpan when the regulator was open or the injectors were working.

Photo: Mike Peart

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By Mike Peart

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