CHAPTER XVII 

 TESTING ELECTRIC FANS AND BLOWERS 



Blowers 



This test is made in accordance with Government 

 specifications issued by the Navy Department under 

 the cognizance of the Bureau of Construction and Repair. 

 Use of Air Tube 



When making a fan test the temperature of the air 

 near the fan should be taken by two Fahrenheit ther- 

 mometers, one hanging free in the air and the other 

 with the bulb wrapped in thin cloth, this cloth being 

 saturated by having its lower end placed in a small 

 receptacle filled with water. The water must be at the 

 maximum temperature which it will naturally attain 

 in the room. Corrected barometer reading must also 

 be recorded on the test sheet. 



The method of finding the weight of air from the air 

 tables (mentioned in the specifications) is as follows: 

 On the page containing the dry bulb reading, as given 

 by the test sheet, is noted the corresponding barometer 

 reading. In the column under the dry bulb temperature 

 and opposite the barometer reading, the corresponding 

 weight of air is given. The weight of air found in the 

 table must then be corrected to correspond with the 

 corrected barometer reading found in test; this correc- 

 tion being found in the second line from the top of the 

 page. Correction must also be made for the difference 

 between the wet and dry bulb temperatures by adding 

 to the weight of air already obtained the number corres- 

 ponding to the numerical difference between the wet and 

 dry bulb reading, found in the third sub-division under 

 dry bulb temperature. The numerical differences are 

 tabulated in the second sub-division of the column. 



Example: 



Given barometer reading 30. 15 in. 

 Dry bulb reading 67 deg. F. 

 Wet bulb reading 59 deg. F. 

 1147] 



