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Coal, Boilers, Chimney and Smoke

Coal

Coal for Crofton was originally delivered by canal from the Somerset Coal field. it was unloaded on a specially constructed wharf just below Crofton Lock and then brought up to the Station via an iron tramway. The boiler ash was taken out by the reverse process. A piece of rail from the old iron tramway remains at Crofton in the yard by the Boiler House entrance.
Later, when GWR took over, the coal was delivered by rail/road. To this end, a railway siding was created about half mile to the west of Crofton. The final part of the coal’s journey was then by road. In order to get the horse drawn waggons into the site, GWR had to create a driveway around the end of the building which previously has sloped directly down to the railway line below. This driveway was made of boiler ash, a large quantity of which had accumulated at Crofton as the process of removing the ash by canal had been discontinued some time earlier.
Nowadays, the coal is delivered by road from a pit in the Midlands. When in steam, Crofton consumes about 1¼ tonnes of coal per day. Allowing for the extra coal needed for warming up and the necessary private trials at the beginning of each season, Crofton’s annual consumption is about 30 tons.
Child visitors are frequently fascinated by the sight of the coal in the bunker, as many have never seen it ‘in the flesh’ so to speak. Its not unknown to see a small child leaving Crofton carefully clutching a piece of coal wrapped in one of Crofton’s souvenir paper bags!

Boilers

Since it was built, Crofton has had three designs of boiler, reflecting the developments of stationary boiler technology.
In 1807 when the first engine was installed, boiler technology was in its infancy. Sustainable steam pressures were very low because little was known about pressure vessel design and because suitable material for their manufacture was only available in small sheets of variable quality. The first boilers at Crofton were to the Waggon design, (described here). Waggon boilers were so called because they were shaped like farm carts. These boilers operated at a steam pressure of only 0.35 bar (5 psi). Waggon boilers were not very energy efficient.
The second type of boiler installed at Crofton was the Cornish Boiler. Cornish boilers (described here) were much more efficient than Waggon boilers, and capable of sustaining much higher pressures. The first Cornish boilers at Crofton were installed by Harvey’s of Hayle in 1844, and ran at a pressure of 1.4 bar (20 psi).
The final type of boiler installed at Crofton was the Lancashire Boiler. Lancashire Boilers represent the ultimate and final development of the stationary steam boiler.
Two boilers to the Lancashire design were installed at Crofton by GWR in 1896 and 1903. These provided the steam for the station right through until the 1970’s when they were condemned. The front of one of these boilers still exists at Crofton at the entrance to the shop, giving the visitor the opportunity to examine both the outside of the front piece, and, from within the cafe, to see what such a boiler looks like inside. It was fortunate that when these boilers were condemned, a suitable replacement became available from a company which was demolishing one of its factories in Bristol which was equipped with a Lancashire boiler in good condition. This is the boiler now used to provide the steam at Crofton. It is, in itself, no youngster, having been made by Beeleys of Hyde, Manchester in 1899. But it was obviously well looked after when it was in service, and having been designed to run at 12.4 bar (180 psi) it is now enjoying a relaxed retirement running at Crofton’s present operating pressure of a delicate 1.4 bar (20psi). Given its present condition, we believe that it has many more years of life left but we do have a ‘back stop’ thanks again to same company, who made another Lancashire Boiler available to us when they demolished their factory in Swindon. This one was made by the Vulcan Works in 1914. It is now preserved on site and can be seen near the entrance by the Warden’s cottage. Both of these boilers are 2.3 m (7.5 ft) in diameter by 8.5 m (28 ft) long and weigh about 22 tonnes. They have a working water capacity of 18,000 litres (4,000 gallons/18 tonnes).
In order to prolong the life of such a boiler, it is imperative that it be warmed up gently. To be ready to run the engines at 10:30 a.m. on a typical Saturday of a steaming weekend, Crofton’s boiler is lit with a small fire at about 9:30 a.m. on the preceding Thursday, burned gently throughout that day and allowed to go out overnight. The fire is then relit on the Friday morning and again burned gently throughout the day.
On the Saturday morning, the duty boiler man arrives at 7:00 a.m., rakes out the ashes, relays and relights the fire and builds it up to ensure a reasonable head of steam is available for the engine warm though to be started at 9:00 a.m. (in order to avoid damage, steam must be blown through the pipes, valves and cylinders for at least an hour before they are run). From this point, the fire is built to produce a full head of steam for the first engine run at 10:30 a.m.

Chimney

The history section describes how in 1959, the chimney had to be truncated because of structural instability. In fact it had developed a most pronounced banana like curve! This is quite common with tall chimneys. The side facing the prevailing wind becomes colder than the other side, resulting in a larger build up of combustion acids in the mortar on that side. Eventually this mortar crumbles due to the dissolving effects of the acids and the chimney begins to bend. Before the new top was built onto the old stump, a series of stainless steel anchor rods were fixed between the top of the stump and the foundation and these were tensioned to provide stabilisation.
At the end of the steaming week end, the fire is allowed to go out and the boiler given several days to cool down before it is completely filled with treated water to become ‘water wedged’. The purpose of water wedging is to exclude as much air as possible from the boiler shell to prevent corrosion.

Smoke

There is a section in the Act of Parliament relating to  The Kennet & Avon Canal, dated 1794 which, in modern language, stipulates the following:- The Engines must consume their own smoke’.
Should any engine man employed by the canal company cause smoke to rise from the pumping station and a complaint be made by the Earl of Ailesbury from Tottenham Park House, then the person responsible for the nuisance will be discharged and never employed in the service of the company’.
Here is the actual wording used, which makes interesting reading in its own right :
ANNO REGNI TRICESIMO SEXTO Cap. 44.VII
And whereas it is intended that One or more Steam Engine or Steam Engines shall be created near the House of the Earl of Ailesbury, in the Parish of Great Bedwin aforesaid, called Tottenham Park House, and used for raising Water for the Supply of the Summit Level, and the Smoke which would arise from the same, if such Engine or Engines was or were constructed and used in the common Way, would be a great Nuisance to the Inhabitants of the said House; be it enacted, That no Steam Engine or Steam Engines, or other Engine or Engines worked by Fire, shall be erected or used at any Time for ever hereafter by the said Company of Proprietors within the Distance of Two Miles from the said House, unless the same shall be constructed, made, and used, so as to burn and consume the Smoke of the Coals or other Combustibles and Fire with which such Engine or Engines shall beworked, in as complete a Manner as the Nature of the Case willadmit; and that the same, if erected, shall be so worked, and theCoals so placed in the Furnace or Furnaces of such Engine orEngines, as to make as little Smoke, and be as small a Nuisance as possible; and that if the Person or Persons, at any Time or Times employed by the said Company of Proprietors to superintend such Engine or Engines, shall refuse or neglect to use the same, or place the Coals in the Furnace or Furnaces of such Engine or Engines, in such Manner as to make as little Smoke as possible, the said Company of Proprietors, upon Complaint made thereof to the Principle Clerk to the said Company of Proprietors, by the Owner or Owners of the said House for the Time being, shall, within Thirty Days after such Complaint made, discharge such Person or Persons from the Service of the said Company, and never afterwards employ him or them.

This maybe explains why a constant supply of volunteers is urgently needed at Crofton to fire the boiler…….

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