116 



AS TO SERVICES AND METERS 



of the size represented. They may even pass more than this 

 when installed on pipe of larger diameter. 



Manufacturers' ratings of the capacities of meters have been 

 somewhat arbitrary and are usually higher than the limits of 

 ordinary practice. Recently the practice has been adopted of 

 stating capacities as the quantities that will pass under 25 

 pounds loss of head in the meter. 



Different types of meters vary greatly in frictional resistance. 

 The following table shows approximate representative figures 

 for the sizes of meters in common use. 



CAPACITY AND RESISTANCE OF WATER METERS 



There is considerable variation in the frictional resistance 

 of meters of different makes and also in meters from the same 

 factory at different times, and the above is to be taken only as a 

 general approximate indication. These capacities have been 

 used for another purpose in Chapter IV, p. 34. 



It is further to be noted that there is a recent tendency to 

 introduce intermediate and odd sizes of meters and meters of 

 special capacities. 



Load Factor. In that which follows, the percentage which 

 the actual average sales from any meter is of the moderate 

 rating in the above table will be referred to as the " load factor." 

 Thus a 2-inch meter passing i ,000,000 gallons of water per annum, 



