英文文献：年产万吨的苹果汁工厂设计

英文文献

2.5.

3. Design and construction of the building

Roofs and ceilings

Walls

Windows and doors

Floors

Lighting and power

Water supply and sanitation

Layout of equipment and facilities

In general, a building should have enough space for all production processes to take place without congestion and for storage of raw materials, packaging materials and finished products. However, the investment should be appropriate to the size and expected profitability of the enterprise to reduce start-up capital, the size of any loans taken out and depreciation and maintenance charges.

Roofs and ceilings

In tropical climates, overhanging roofs keep direct sunlight off the walls and out of the building. This is particularly important when processing involves heating, to make working conditions more comfortable. Fiber-cement tiles offer greater insulation against heat from the sun than galvanized iron sheets do. High level vents in roofs both allow heat and steam to escape and encourage a flow of fresh air through the processing room. The vents must be screened with mesh to prevent insects, rodents and birds from entering the room. If heat is a serious problem, the entrepreneur could consider fitting electric fans or extractors, although this clearly increases capital and operating costs.

Rafters or roof beams within the processing and storage rooms are unacceptable. They allow dust to accumulate, which can fall off in lumps to cause gross contamination of products. Similarly, insects can fall from them into products. They also allow paths for rodents and birds, with consequent risks of contamination from hairs, feathers or excreta. It is therefore essential to have a paneled ceiling fitted to any processing or store-oom, with careful attention when fitting them to ensure that there are no holes in the paneling. Care should also be taken to prevent birds, rodents and flying insects gaining access to the processing room through gaps in the roof structure or where the roof joins the walls.

Walls

As a minimum requirement, all internal walls should be rendered or plastered with a good quality plaster to prevent dust forming in the processing room. An experienced plasterer should be used to ensure that no cracks or ledges remain in the surface finish, which could accumulate dirt and insects. The lower area of walls, to at least 1.08 metres (four feet) above the floor, is most likely to get dirty from washing equipment, from product splashing etc. and special attention should be paid to ensure that this area is easily cleaned. Higher areas of walls should be painted with a good quality emulsion. The lower parts of walls should be either painted with a waterproof gloss paint, preferably white, to allow them to be thoroughly cleaned, or ideally they should be tiled with glazed tiles. If tiling a process room is too expensive, it is possible to select particular areas such as behind sinks or machinery and only tile these parts. In some countries there is a legal requirement for specified internal finishes and this should be checked with the Ministry of Health or other appropriate authority (see also Section 2.4.2)

Windows and doors

Window sills should be made to slope for two reasons: to prevent dust from accumulating and to prevent operators from leaving cloths or other items lying there, which in turn can attract insects. Windows allow staff to work in natural daylight, which is preferable to and cheaper than electric lighting. However, in tropical climates there is a natural inclination for workers to open windows to allow greater circulation of fresh air. This provides easy access for flying insects, which can readily contaminate the product. Windows should therefore be fitted with mosquito mesh to allow them to be left open.

Normally doors should be kept closed, but if they are used regularly there is again a tendency for them to be left open with similar consequences of animals and insects entering the plant. In this case, thin metal chains or strips of material that are hung vertically from the door lintel may deter insects and some animals, while allowing easy access for staff. Alternatively mesh door screens can be used. Doors should be fitted accurately so that there are no gaps beneath them and all storeroom doors should be kept closed to prevent insects and rodents from destroying stock or ingredients.

Floors

It is essential to ensure that the floors of processing rooms and storerooms are constructed of good quality concrete, smooth finished and without cracks. In some developing countries, it is possible to buy proprietary floor paints or vinyl based coatings, but these are usually very expensive. Generally, it is not adequate to use the red wax floor polishes that are commonly found in households, as these wear away easily and could contaminate either products or packages. Over time, spillages of acidic fruit products react with concrete and