3252 



STORAGE 



STORAGE 



flax fibers. It is prepared in sheets or quilts, from J4 

 to Yi inch thick, somewhat like cotton-batting. These 

 sheets are ordinarily quilted between water-proof 

 paper. This material is used largely for insulating 

 household refrigerators and refrigerator cars. 



Mineral wool is also known as rock-wool, rock-cot- 

 ton, rock-cork, or silicate cotton. This material is 

 usually made from the slag of blast furnaces with the 

 addition of limestone. Rock-wool is usually made from 



LAP SIDE WALL PAPER 



PAPER 



O 



^ 

 H 



Wo 



SIDE WALL PAPER 



3702. Diagram showing proper construction of wall insulated 

 with mill shavings. 



a mixture of granite particles and limestone. The 

 crushed rock is mixed with coke and fused in furnaces 

 at a temperature of about 3,000 F. ; the molten slag or 

 rock is run out through the bottom of the furnace by 

 a high-pressure steam blast. This blows the slag into 

 very fine shreds or fibers, much resembling fleece or 

 wool. The result is a material which contains from 

 92 to 96 per cent air spaces and, although consisting 

 primarily of a substance of high-heat conductivity, is 

 fairly efficient as insulation. It is practically vermin- 

 proof, fire-proof, and not liable to decay. It absorbs 

 moisture very easily, and one of the greatest disadvant- 

 ages is the difficulty of handling. The fibers are very 

 penetrating and are glass-like, which result in consider- 

 able inconvenience in handling the material. 



Lith is a manufactured insulation composed of flax 

 fibers, lime rock-wool, and water-proofing compound. 

 It is prepared in boards of standard sizes and thick- 

 nesses and is accepted as a standard insulation by 

 refrigerating engineers. It is a very efficient insulating 

 material. 



Common forms of insulating material which are 

 usually at hand or can be easily obtained for the con- 

 struction of storage buildings are : straw, chaff, hay, dry 

 grass, dry leaves, hulls of various grains, sawdust, and 

 mill shavings. 



All except sawdust and mill shavings can be con- 

 sidered as suitable only for temporary structures. 

 These materials are ah 1 fairly efficient as non-conductors 

 of heat provided they are dry and means are used to 

 keep them in a dry condition after being built into the 



walls. There is also some danger from the depreda- 

 tions of rats, and the greatest possible care must be 

 used to prevent these rodents from gaining entrance. 

 Sawdust from different woods has about the same 

 insulating effect. The sawdust must be thoroughly 

 dried, otherwise its efficiency as insulation is very 

 greatly impaired and, in addition, there is danger of 

 fermentation and heating, and even spontaneous 

 combustion. It is more difficult to obtain dry sawdust 

 than mill shavings, and whenever sawdust is used 

 it should be very carefully dried before being placed 

 in the walls. It has not as great elasticity as mill 

 shavings and, consequently, is likely to settle after 

 packing unless very carefully pressed into place. 



Mill shavings consist of small chips and shav- 

 ings from planing mills. This material has largely 

 insulating purposes and is 

 is obtained easily in a dry 

 fact that the mills of this 

 lumber. It is much more 



elastic than sawdust and does not pack or settle 

 down. If thoroughly dry, and means are taken to 

 keep it so, it is a very efficient insulating material 

 and will remain in good condition for many years. 

 It should be packed in the walls at the rate of eight 

 or nine pounds to a cubic foot. 



Whenever walls are filled with insulating material 

 in loose condition, much will depend upon the 

 method of constructing the walls. Not only is it 

 necessary to use the lumber and insulating material 

 in a dry condition, but unless the walls are prop- 

 erly built, the insulation will not remain dry any 

 great length of time. Walls that are not practically 

 air-tight allow the outside air to gain entrance and 

 to mix with particles of insulating material; con- 

 densation of moisture takes place, and the insulating 

 efficiency of the material is seriously impaired. The 

 conditions for the condensation of moisture upon the 

 insulation particles are ideal unless special means 

 are used to prevent it. Contact with the inside walls 

 lowers the temperature of the insulation to such an 

 extent that when the warmer air from outside comes 

 into contact with it, the moisture is deposited and 

 absorbed. Therefore, it is necessary to build the walls 

 in such a way that they will be practically air-tight. 



This is accomplished by having layers of elastic water- 

 proof paper on the outside and inside of the walls. The 

 proper method of constructing such walls is shown in 

 Fig. 3702. The wall consists of two layers of matched 

 boards on each side, between which the water -proof 

 paper is placed. The figure also shows the proper 

 method of overlapping the paper at the corners. It is 

 very essential that these details be attended to; it is 

 also necessary to prevent the tearing or breaking of the 

 paper when placing it, and for this reason only elastic 

 paper should be used. The more brittle forms of paper 

 are so easily broken that it is almost impossible to 

 place them without seriously injuring them. Any 

 breaks at the corners or tears in the paper will allow 

 considerable air leakage into the walls and very seri- 

 ously impair their efficiency. This is probably one of 

 the most important details in the construction of stor- 

 age houses, both for cold-storage and for common-stor- 

 age purposes. Too great stress, therefore, cannot be 

 placed on this point. 



Storage temperatures; humidity. 



The general principles governing the application of 

 low temperatures to the preservation of fruit products 

 depend primarily on the fact that temperature is the 

 most important factor governing the life activities of 

 these products. A fruit or vegetable is a living organism 

 in which the functions or life processes are continually 

 proceeding as long as the body remains in a normal 

 condition. The various processes of ripening depend 

 upon the chemical and physiological changes within the 



