Insulation

“ In this respect the phenomenon followed the same rule as that to which telegraph wires are subject—namely, that the loss of insulation is greater in damp, murky weather when the insulators are covered with wet dust than during heavy rains when the insulators are thoroughly washed by the action of the water. In like manner a heavy rain-storm cleaned the tracks from the accumulations due chiefly to the droppings of the horses, which otherwise served largely to increase the conductivity. ”

“ When the outgoing and incoming wires are both placed upon or underground the strain upon the insulation is very much increased, for then instead of the two lines being separated by fifteen or twenty feet of pole, which is a very fair insulator, they are separated by only a few inches of earth or perhaps metal, the first of which is a fairly good conductor, while the last is a nearly perfect one. It is evident, therefore, that the insulation proper in an underground or surface system must be of the highest order. ”

“ If the conduits in which the wires are located could be kept perfectly dry, there would be no difficulty in obtaining insulation that would withstand the strain it is subjected to; but rain in summer and snow in winter will at [566] times cover the tracks and fill the conduits, hence the securing of perfect insulation presents great difficulties. The manner in which inventors have sought to surmount the obstacles can be made clear by the aid of a few illustrations of typical designs.
Fig. 25.—Underground Conduit with Protecting Shield for the Conductor. ”

“ If the insulation per mile, i.e., the total insulation multiplied by the mileage of the wire loop, is found to be less than 200,000 ohms, the wire is considered to be faulty. The climatic conditions in the British Islands are such that it is not possible to maintain, in unfavourable weather, a higher standard than that named, which is the insulation obtained when all the insulators are in perfect condition and only the normal leakage, due to moisture, is present. ”

“ In the second, means had to be discovered for protecting it, when so cooled, from the influx of external heat, and since the rate at which heat is transferred from one body to another increases very rapidly with the difference between their temperatures, the question of efficient heat insulation became at once more difficult and more urgent in proportion to the degree of cold attained. ”

“ You say the cooler is perfectly dry inside, therefore, its construction must be very good, but the outside insulation is not just right, so the outside becomes too cool and the moist air coming in contact with the cold surface readily condenses. If the cooler can be insulated in such a way that the outside will not become so cold, we have no doubt your trouble can be overcome. ”

“ Pipes may be insulated to prevent freezing, but this is not a completely dependable method. Insulation does not stop the loss of heat from the pipe—merely slows it down—and the water may freeze if it stands in the pipe long enough at below-freezing temperature. ”

“ It was desirable in this instance to use the upper floors of the building for warm storage, consequently the top encasing insulation is placed on the ceiling of the sixth story, continuing to and meeting the wall insulation, which with the wall insulation encases the cold storage, as spoken of for the ideal. The floor construction is of flat ceiling type, there being no girders to contend with in piling product or installing piping. ”

“ Boilers and all steam-surfaces were covered with the magnesia covering.
So it appears that not alone is the man who pays for the coal interested in this question of most perfect insulation, but also the men who operate the plant as well. ”

“ The insulating joint may be omitted in conduit, armored cable, or metal molding systems with straight electric fixtures in which the insulation of conductors is the equivalent to insulation in other parts of the system, and provided that approved sockets, receptacles, or wireless clusters are used of a type having porcelain or equivalent insulation between live metal parts and outer metal shells, if any. ”

“ It is one merit of the low-temperature work, I repeat, to have called attention to the possibilities of heat insulation in application to "the useful purposes of life." If Professor Dewar's vacuum vessel can reduce the heat-transmitting capacity of a vessel by almost ninety-seven per cent., why should not the same principle, in modified form, be applied to various household appliances—to ice-boxes, for example, and to cooking utensils, even to ovens and cook-stoves? ”

“ To the passenger, the presence of the steel construction is apparent, but the insulation, which forms a vital factor in the car's construction, can be seen only during the process of building. Composed of a combination of cement, hair, and asbestos, this insulating material is packed into every cubic inch of space between the inner and outer shells of the roof and sides, forming a perfect non-conductor to protect the passengers against the biting cold of winter or the heat of summer sunshine. ”

“ Electrical inspection indicates that the winding is melted together in several places. You couldn't unwind the coil, let alone rewind it with fresh insulation. We've got a couple of gallons of insulation handy, if you get a good idea. ”

“ The ability to maintain a satisfactory temperature depends as much upon the construction of the house as upon the heating apparatus itself. Heat is readily lost through walls, roofs and windows. Most houses can be made more comfortable at small cost by applying insulation or by correcting defects in construction. ”

“ When the outside surface of an insulator is wet, as during a moderate rain, it seems that the under surface of the insulator, and the distance through air from the lower wet edge of the insulator to the pin or cross-arm, make up most of the insulation that prevents arcing over from the wire to the pin or cross-arm. It further appears that it is useless to extend the distance across the dry under surface of the insulator indefinitely without a corresponding increase of the direct distance through air from the lower wet edge of the insulator to the wood of cross-arm or pin. ”

“ If the potentials are so low that streamers do not form, then it is even disadvantageous to employ oil, for it may, principally by confining the heat, be the cause of the breaking down of the insulation. ”

“ In that treeless land the oven-birds look on telegraph-posts as specially provided by a benign Providence to afford them eligible nesting-sites, and from some perversity of instinct, or perhaps attracted by the gleam of the white earthenware, they invariably select one of the porcelain insulators as the site of their future home, and proceed to coat it laboriously with clay, thus effectually destroying the insulation. ”

“ The flat roof should be covered with good roofing and well-insulated for comfort in both summer and winter as described in the working drawings. The cost of the insulated flat roof should not be greater than that of an ordinary pitched roof without insulation. The accumulation of snow will help to keep the building warm. ”

“ Moist air also will spoil the insulation of non-conducting supports. All bodies are more or less hygroscopic, and the moisture condensed on their surfaces thus turns the best insulators into conductors. ”

“ While a commercial ice chest provides good insulation of both the samples/specimens and the coolant, it is best to place extra insulation and cushioning around the metal cans inside the chest. Newspapers, plastic bubble wrap, and foam rubber may all be used with almost equally good results except newspapers and standard ice do not mix well. ”

“ In pole and over-house lines, the wires are kept from each other and the current from escaping to the earth by insulators of glass. In Europe white porcelain and brown stoneware insulators are used, and the former substance, when of good quality, well glazed and well burned, is perhaps the most perfect of all insulating materials, and does not deteriorate with age. The fewer the poles on which the wires are suspended, the better is the insulation and the less the cost, but the liability to accident is greater. ”

“ A peculiar property of oils, and liquid insulation in general, when subjected to rapidly changing electric stresses, is to disperse any gaseous bubbles which may be present, and diffuse them through its mass, generally long before any injurious break can occur. ”

“ Two strain insulators having a tensile strength of 1,000 pounds suspend the aerial between two masts, besides providing a further insulation of 75,000 volts. One of the masts is a steel pole erected on the roof of the house, the top of which is 43 feet above ground. ”

“ As insulating materials, whether rubber, cotton, or paper, may be impaired or destroyed by heat, it is necessary that the temperature of underground cables under full load be kept within safe limits. Rubber insulation can probably be raised to 125° or 150° Fahrenheit without injury, and paper and cotton may go a little higher. For a given size and make of leaded cable the rise of temperature in its conductors above that of the surrounding air, for a given loss in watts per foot of the cable, may be determined by computation or experiment. ”

“ The more dense or heavier the material used in building, the more cold radiated from all surfaces unless effectually cut off. In ordinary type of construction the various floors rest on exterior walls and in no way is it possible to prevent a very great loss of cold being carried through the floors, thence to the walls and dissipated thereby. Such matters are not trivial in their importance. At one wholesale distributing market deterioration in insulation during six or seven years has necessitated the doubling of refrigerating machine service and the volume of business is practically the same. ”

“ If not insulated, your house can lose a quantity of heat at these points. Remember, heat rises and, after a storm, if the snow on the roof of your house melts quicker than on those of your neighbors, it is a clear demonstration that you are wasting heat by letting it ooze through certain minute apertures. Another way to combat this upward radiation is to pour a loose, featherlike insulating material into the space between the attic flooring and the plaster of the bedroom ceilings. ”

“ Between the bed of concrete, mentioned previously, and the foundation-masonry and between the foundation and the engine-frame, a layer of insulating material may well be placed. Preference is to be given to substances not likely to rot or at least not likely to lose their insulating property, when acted upon by heat, moisture or pressure. ”

“ As for directly storing up solar heat in good conductors or absorbents of heat which are then to be insulated—for instance, receiving the heat in porous black stones which are first exposed to the sun and afterward thrown into a great reservoir, just as snow is piled up in the ice-house—it involves no impossibility. ”

“ Ice; and how is this to be kept away either under ground, or under the shade of trees? Abundant experience has proved, that no thickness of wall, that no cement of any kind, will effectually resist moisture. Drops will, at times, be seen hanging on the under side of an arch of any thickness, and made of any materials, if it have earth over it, and even when it has the floor of a house over it; and wherever the moisture enters, the ice will quickly melt. ”

“ Straw, sawdust, wool, feathers, confined air, are insulating substances which retain heat. We might surround with a double envelope of this kind the reservoir holding the sun-heated stones, and in this way we might have our store of solar heat, as now we have our store of ice. It is one problem whether we have to retain cold or to retain heat. ”

“ It will be well to understand a little more in detail how to heat glass structures, as temperature is, next to moisture, the most important factor of success. If steam or hot water is used in the dwelling house and a greenhouse of the lean-to type is used, the problem becomes a very simple one, as additional pipes can be run through the greenhouse. But as this advantage is not always ready to hand, we will consider the heating of an isolated house, and the principles involved may be adapted to individual needs. ”

“ This comprises about the whole system of arrangements in the construction for warming the house with heat radiated from the floors and interior walls.
Its mode of operation simply consists in the body of warmed air passing from the heating-chamber upward, through the walls and under the floors, and in its passage giving up its surplus heat to the surfaces of these flues. As the air becomes reduced in temperature, it naturally descends through the pipe and trunk passage-ways provided for its return to the heating-chamber, where it is again recharged with heat. ”

“ In one case the heat is to be kept from penetrating, in the other from escaping, and both require the same treatment; not, perhaps, to the extent of stuffing with sawdust,—confined air is just as good,—but the walls and the floors, the roofs and the windows, should be made to prevent the escape of heat. He may think I underrate his scientific attainments, but it will do no harm to remind him that an air-tight house may be a very cold one. A man would freeze to death in a glass bottle, when a coarse, porous blanket would keep him comfortable. ”

“ All the heat used ought to be concerned in ventilation, and in that only. To secure air-tight walls and ceiling, the studding and joists should be boarded in, both on the inside and out, and the space between should be filled with shavings, straw, dry moss, or any similar fibrous substance. The outside sheathing must be well laid and must be water-tight in order that rain shall not penetrate to the inside of the wall, and the roof must be tight so that the ceiling filling does not get wet and rot. ”