Carpentry and Contracting: A Practical Reference Work on Carpentry, Building Superintendence, Etc, Том 4

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American technical society, 1919
 

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Сторінка 2 - BAKER Professor of Civil Engineering, University of Illinois, Author of " A Treatise on Masonry Construction.
Сторінка 159 - British thermal unit is the amount of heat required to raise the temperature of 1 pound of water 1 degree Fahrenheit.
Сторінка 57 - BTU The temperature of steam at 3 pounds' pressure is 220 degrees, and 220 — 70 = 150, which may be taken as the average difference between the temperature of the steam and the air of the room, in ordinary lowpressure work. Taking the above results, we have 150 X 1 .7 = 255 BTU as the efficiency of an average cast-iron or pipe radiator. This, for convenient use, may be taken as 250. A circulation coil made up of pipes from 1 to 2 inches in diameter, will easily give off 300 BTU under the same conditions...
Сторінка 35 - For the best types of househeating boilers, we may assume a combustion of 5 pounds of coal per square foot of grate per hour, and an average efficiency of 60 per cent, which corresponds to 8,000 BTU per pound of coal, available for useful work. In the case of...
Сторінка 120 - The ordinary pet-cock air-valve is the most reliable for hot-water radiators, although there are several forms of automatic valves which are claimed to give satisfaction. One of these is shown in Fig. 104. This is similar in construction to a steam trap. As air collects in the chamber, and the water-line is lowered, the float drops, and in so doing opens a small valve at the top of the chamber, which allows the air to escape. As the water flows in to take its place, the float is forced upward and...
Сторінка 55 - The pipes are eitherconnected in pairs at the top by return bends, or each separate tube has a thin metal diaphragm passing up the center nearly to the top. It is necessary that a loop be formed, else a "dead end
Сторінка 58 - X 225 = 240; that is the efficiency varies directly as the difference in temperature between the steam and the air of the room. It is not customary to consider this unless the steam pressure should be raised to 10 or 15 pounds or the temperature of the rooms changed 15 or 20 degrees from the normal. From the above it is easy to compute the size of radiator for any given room. First compute the heat loss per hour by...
Сторінка 68 - Return. between the riser and radiator is above the floor; and the third, when the radiator has to be set close in the corner of a room and there is not space for the usual connection. A globe valve should never be used in a horizontal steam supply or dry return. The reason for this is plainly shown in Fig.
Сторінка 110 - Connections. temperature of 170 degrees in the radiators. Variations may be made, however, to suit the existing conditions of outside temperature. We have seen that an average...
Сторінка 125 - In schoolhouse and hospital work, where larger volumes of air are warmed to lower temperatures, an efficiency as high as 500 BTU may be allowed for radiators of good form. Flues and Casings. For cleanliness, as well as for obtaining the best results, indirect stacks should be hung at one side of the register or flue receiving the warm air, and the cold-air duct should enter beneath the heater at the other side. A space of at least 10 inches, and preferably 12, should be allowed for the warm air above...

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