Food-Processing-Plant-Design-layout

Food Processing Plant Design & layout
Terrazo
Ceramic tiles
15.12 Wood
Wood is of two types – hard wood and soft wood. Hard wood is used for building
construction and soft wood is mostly used for packaging material and boxes. Plywood is
obtained from inferior quality wood after some processing, and it is used for making
furniture. Hardwood is seasoned to reduce moisture content and is also treated with
creosote oil. Hard woods are used in the room where moist conditions prevail and it is
properly seasoned to prevent any kind of mould growth and contamination. Soft woods are
used in the dairy for cold store doors and covered with stainless steel sheet.
Soft wood is obtained from trees of Deodar, Kali, Chir, Pine, Walnut and Spruce etc. Soft
woods are resinous and light in colour. It is general characteristics that trees having needle
like leaves give soft wood.
Sal, Teak, Shisham, Pyngado, Oak, Beach and Ash are some of the examples of hard wood
obtained from broad leaf trees. Hard woods are relatively darker in colour, heavy, close
grained and strong. They are non-resinous.
15.12.1 Timber wood
Timber wood is suitable for building or engineering purposes. When in living tree, the
timber is called „standing timber‟. When trees are cut down, it is called „rough timber‟ and
when it is sawn into various market sizes, such as beams, battens, posts, planks etc., it is
called „convert timber‟
15.12.2 Seasoning of wood
The growing tree contains a large amount of moisture which may be 150% of the dry
weight of the timber. The process of removal by drying the excess moisture from the wood
in a controlled manner to prevent the shrinkage which occurs, causing cracks and other
defects is called seasoning. Seasoning may be natural or artificial. Natural seasoning is best
but it takes long time. Artificial seasoning may be water seasoning, boiling or kiln
seasoning.
15.12.3 Preservation of wood
Timber is liable to attack by dry rot and other fungi. The function of a preservative is to
poison the food matter in the timber. But this poison should not be dangerous to carpenter
and must not wash out in rain. The best time to apply preservatives is the early summer.
The usual methods of preservation are tarring, charring, painting, creosoting, solignum
paints and Ascu treatment.
Tarring consists of coating the timber with hot coal tar. Tarring is adopted only for work of
rough character such as timber fences, ends of doors and window frames built into walls.
Charring is adapted to the portions which are embedded in the ground. The ends of posts
are charred over a wood fire to a depth of about ½” and then quenched with water.
Painting consists of applying 3 or 4 coats of an oil paint. Solignum paints are effective
preservatives against attack by white ants. The process of Ascu treatment for the
www.AgriMoon.com
108