BUILDING 173 



unsatisfactory as well as dangerous. If ample driving power is 

 not available a flywheel will assist materially. 



Slings, lifting devices, hooks, etc., should be designed with 

 ample safety factors and to allow safe, accurate and rapid assembly. 



Wire slings should be oiled to prevent rusting and protected 

 from kinking or cutting on sharp corners by pads or their equiva- 

 lent. Angle pieces made from boiler plate are good, cheap and 

 durable. Any slings that show wear or weakening should, of 

 course, be replaced. 



Ventilation. 1 Particular attention must be given to the ven- 

 tilating problem in the design of the building; especially for large 

 installations where the heat to be carried away from the generators 

 is very great. The oversight of this important feature in stations, 

 otherwise well designed, has led to considerable trouble from over- 

 heating the machines; for if no provision is made for admitting 

 fresh air, the air in the machine pit and in the space around the 

 machine is used over and over again. Fresh cool air can be taken 

 to the generator pit through ventilating ducts especially built for 

 this purpose below the floor, and from the pit the air is drawn up 

 through the machine by the fanning action of the rotor or forced 

 circulation may be provided by motor-operated fans, the heated 

 air escaping through openings in the roof. The size of the inlets 

 and outlets depends upon the losses to be dissipated, the allowable 

 difference in temperature between the inside and outside air and 

 the height of the building. 



Mr. R. C. Muir in the " General Electric Review " gives the 

 following recommendations: " The maximum difference between 

 inside or room temperature and outdoor temperature should not 

 exceed 20 F. (11.1 C.), during hot weather, since the air entering 

 the machine is taken from the room and the air leaving the machine 

 is considerably warmer than the room temperature. The ven- 

 tilation scheme should be laid out for most severe or hot weather 

 conditions. It is very important to make the difference in height 

 between inlet and outlet openings as great as the station will per- 

 mit, as is shown from Table XXXVII. 



The amount of air required for the generating room can be 

 easily calculated, as follows: 



One Kw.-hour will raise the temperature of 10,000 cubic feet 

 of air from 80 F. to 100 F., a rise of 20 F. (11.1 C.). 



1 See also "Generator Ventilation." 



