These are used in factories containing continuous kilns. The kiln or kilns are placed in the centre of the building in such a way that the heat from them spreads to the different storeys by traps in the flooring. When necessary, vertical movable pipes are fixed to the holes in compartments which are cooling to conduct the heat to places where it is required. The bricks are arranged on the floor in hacks as previously described. Shelves are generally useless, except for bricks to be stamped, when the space at disposal is too limited.
The floors are strong enough to bear the weight of the bricks. Casements are placed in the walls, and are opened to produce draughts and hasten the drying of products which are not injured by air-currents. Such a drying-place can be constructed in various ways; above all things economy is desirable. Therefore any building which involves much masonry should not be considered; even iron is not economical enough, and we should recommend the erection of a simple one-storeyed or two-storeyed shed, according to the daily output. In order to avoid the use of pieces of large size which are always costly, we should substitute for them joists fastened together with bolts. Fig. 176 represents a drying - shed constructed in this way. The kiln has 20 compartments of 4 metres, and has a total length of 44 metres; the building over it is 48 metres long, and is divided into 12 bays of 4 metres. Its width is 20 metres, the height of the storeys is 3 metres for the ground-floor and 2 for the others. Not including the surface of the kiln, and reserving the ground-floor for the management of the kiln and repressing of bricks, the surface of the drying-rooms will be: first floor 48 x 20 - 44 x 10 = 5 20 square metres; second floor 48x20 = 960 square metres; third floor 48 x 14 = 672 square metres; making a total of 2152 square metres. From this surface we must take the passages necessary for circulation of vehicles and for ventila tion. We will suppose that the same system of stacking is used as in open-air drying, which is the quickest and most economical.
Fig. 176. Building in Storeys for drying Bricks. (Scale of 8 millimeters to the meter).
Allowing five "feuilles" thickness to the stack, that is about 1.15 metres, the empty space between each stack will be about one metre.
There will be then altogether: on the first floor 10/2.1 5 = 4 stacks; on the second floor 20/2.15 =9 stacks; and on the third floor 14/2.15 = 7 stacks; that is to say, a total of 20 stacks 48 metres in length, and each row in a stack will contain about 585 bricks. As two rows can be placed together, we see that by laying one row per day, 20 x 2 = 40 rows of 585 bricks each can be accommodated; this makes about 23,000 bricks. It is certain then that with a building of the dimensions stated above the daily production might be as much as 25,000 to 30,000, and this even under unfavourable circumstances; for it is rare, as we said on p. 172, that 3 or 4 layers cannot be stacked one over the other. But it must not be forgotten that in winter and in bad weather drying is a slow process.
The building shown in Fig. 177 is closed at the sides by a brick wall of 8 inches thick, provided with windows which allow of air-currents being produced. Some builders make the posts supporting the framework rest on the kiln (Fig. 231). This arrangement is not advisable, for, however strongly the kiln may be built, it undergoes expansion, which after a time would have a dangerous effect on the whole construction; besides, it is not worth while to be exposed to annoyances for such a slight economy.
In the flooring openings are made for the hot air to pass through; the communication between the storeys is effected by staircases or inclined planes, but the bricks are raised by machinery.
Fig. 177. Drying-rooms in Storeys - Elevation of the Gable-end (Scale of 6 1/2 millimetres to the metre].
Storeyed drying-buildings contain open-air or closed drying-rooms according to the season; from the dimensions we have given, it is evident that they occupy a large space, which increases with the daily production. In order to economise space, cost of installation, and labour, attempts have been made to carry out the drying in closed spaces by artificial means.