After 1922 the boilers were consolidated into a range of 12 on the east side and those on the west side were discontinued. The new boilers operated at 160 psi and it would appear that for a number of years, the North winder was fed at this pressure despite it being designed for 90 psi. In 1934, the 160 psi main in the East boiler house was tapped into and a feed was brought into the basement of the east wing of the engine-house. The concrete floor was broken into to allow an isolating valve to be inserted and an Auld’s type reducing valve was placed on the down-stream side of this valve, dropping the pressure to 90 psi for the North winder.

North winder 90 psi steam reducing valve - schematic

After the reducing valve, another feed with its own isolating valve was tapped off the main but the purpose of this is unknown. Beyond this, the incoming main connects with what appears to have been the original feed from the west boiler-house which then turns into the North winder drum-pit where the main throttle valve is located.

The pipe-work in the west wing carries a large trap for any water which may have condensed in the main. The drain in the base was connected to a steam trap which periodically discharged the water. Square bolt-heads on the main pipe-work flanges suggest an early date for this section.

Beyond the throttle valve, the pipe-work feeding the inlet valves was modified to incorporate two valves which were held closed by hydraulic pressure. They dumped the steam pressure from the engine if the winder had an emergency stop. The dumped steam was piped out and discharged behind the East chimney.

All the pipe-work between the throttle valve and the inlet valves has been fabricated from steel pipe and is relatively modern.

North winder steam valve and emergency dump valves from below

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29 Mar, 2010