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 FIGURE 4-1.
Oscillating Piston Meter With Inlet and Outlet Valves
2. LIMITATIONS. Rated maximum capacity for oscillating piston and nutating
disk meters is shown in Table 4-1. Normal flow for these meters should not
exceed approximately one-half of maximum capacity. Operating at maximum
capacity-should be limited to short periods or peak loads occurring after long
intervals. Maximum pressure loss for both types is from 8.5 to 10.0 percent
of maximum operating pressure as shown in Table 4-1. Mechanical drive and
some magnetic drive meters have two changeable gears in the geartrain.
Changing one or both of these gears allows the ratio between the motion of the
piston or disk and the register to be calibrated for maximum accuracy of
registration. When used for cold water service, the turndown ratio for these
u eters is approximately 80:1, depending upon manufacturer, model, and size.
Other limitations are as follows:
Temperature limit is 80F.
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Pressure limit is 150 psig.
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Installation is permanent.
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