connections, as it is accurate for very low flow. A flow above normal causes rapid wear. The disk type of meter contains a measuring chamber of definite content in which a disk is actuated by the passage of water. Each cycle of motion of the disk marks the discharge of the contents of the measuring chamber. By means of gearing, the motion of the disk is translated into units of water volume on the register dial.

When installing a water meter, make sure it is horizontal and that it operates under back pressure. The meter should be located near the pressure- reducing valve at underground level; so in freezing temperatures, ensure the meter is protected from exposure.

Water is measured in terms of rate-of-flow (volume passing in a unit of time) or total volume. Units and equivalents usually are as follows:

NOTE:

IN READING A METER, YOU SHOULD FIRST DETERMINE WHETHER IT IS MEASURING THE WATER FLOW IN CUBIC FEET OR IN GALLONS.

METER DIALS

Two general types of meter dials are used: the straight-reading type and the circular-reading type. Each type is discussed in the following paragraphs.

The STRAIGHT-READING DIAL shown in figure 4-17 may be read in the same way as mileage on an automobile. When the meter register has one or more fixed zeros, always be sure to read them in addition to the other numerals.

In the CIRCULAR-READING DIAL, when the hand on a scale is between two numbers, the lower number is read. If the hand seems exactly on the number, check the hand on the next lower scale. If that hand is on the "1" side of zero, read the number on

Figure 4-17. - Straight-reading meter dial.

which the hand lies; otherwise, read the next lower number. The procedure for reading the circular- reading dial, shown in gallons in figure 4-18, is to begin with the "1,000,000" circle and read clockwise to the "10" circle, the scales registering 9, 6, 8, 7, 2, and 1; respectively, making a total of 968,721 gallons.

Figure 4-18. - Reading the circular-reading meter dial in gallons.