Page 224 - Water Loss Control

Contr olling Appar ent Losses—Customer Meter Inaccuracy 197

12.5.2 Evaluating Customer Meter Accuracy Test Results
Evaluating water meter performance requires both experience and confidence in the
operator’s skill and training in order to correlate testing results with appropriate correc-
tive actions for a given water meter. Included in the following discussion are examples
involving Sensus meters, including Table 12.10, which are provided for illustrative pur-
poses only.

Turbo Meter Evaluation
Meter Size Adj. Vane Test Data Possible Cause
4" W-1000 +15° 90% @ gpm • Broken Rotor Blades
97% @ 100 gpm • Rotor Bearings and/or thrust bearings worn
99% @ 700 gpm • Debris caught on blade
4" W-1000 +5° 100% @ 10 gpm • Jetting from debris (in strainer or caught
103% @ 100 gpm on flow strainer)
105% @ 700 gpm • Installation effects
• Air entrapped in line
• Coating on rotor and/or chamber
4" W-1000 +30° 94% @ 10 gpm • Adjusting vane moved to (−) from original test
98% @ 100 gpm • Installation effects
99% @ 700 gpm • Improper repair

This meter could be recalibrated by moving the value to 0°.

Compound Meter Evaluation
Meter Size Test Data Possible Cause
Low Flow Tests
3"SRH 105% @ 0.5 gpm • Leaking downstream isolation valve
102% @ 3.4 gpm
98% @ 10 gpm
High Flow Tests
3"SRH 88% @ 25 gpm • Damage to propeller
94% @ 55 gpm • High flow chamber wear
99% @ 280 gpm • Coordinator wear
• Vertical shaft binding and/or bushing wear
3"SRH 95% @ 0.5 gpm • High flow side geared too high
99% @ 3.4 gpm • Debris causing jetting
100% @ 10 gpm • Installation effects
106% @ 25 gpm
108.7% @ 150 gpm
108% @ 280 gpm

TABLE 12.10 Evaluating Customer Meter Accuracy Test Results (Continued)