In order to drain a boiler for maintenance or repair, some means of emptying the water is required. On Lancashire boilers a drain or blow-down valve, connected via an elbow underneath the front of the boiler, is fitted.  The valve is connected to a pipe below floor level, running the length of the boiler-house and discharging into a convenient culvert. 

 Although Lancashire boilers are fitted with a small man-hole at the bottom of the front plate to allow cleaning, before the advent of effective water-softening techniques accumulations of sludge in the bottom of the boiler occurred continuously and were cleared out of the boiler by regularly opening the valve for a short while. Hence the alternative name of “sludge cock”.

Lancashire boiler drain outlet

How the discharge from the boilers was handled prior to 1922 is unknown, but after that time it is believed to have passed into a culvert beneath the South heapstead which also carried the discharge from cylinder drains etc in the engine-house.  Prior to entering the culvert it passed into a small channel with a perforated steel plate at the end which filtered out the larger debris.  The eventual destination of the culvert is unknown, maybe it discharged into the South shaft below decking level, although this seems unlikely since it could wet the men riding in the cage.  

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05 May, 2009