Wis. Admin. Code Public Service Commission PSC 134.27
All meters shall be set as close to 100% accurate as possible. Diaphragm meters shall be considered correct for service if the results of the multiple tests called for agree within 1% and no test shows an error of more than 1% fast or slow. Turbine and rotary displacement type meters shall be considered correct for service when tested at approximately 10% of rated flow with accuracy between 2% slow and 2% fast, and at approximately 100% flow with accuracy between 1% slow and 1% fast and in the case of turbine type meters, have a spin test time equal to or greater than that on file with the commission under s. PSC 134.28(6). In orifice type meters, the deviations in the diameter of the orifice shall not exceed the following:
PRACTICAL TOLERANCES FOR ORIFICE DIAMETERS
Orifice Size | Tolerance Plus or Minus | Orifice Size | Tolerance Plus or Minus |
.2500 ..... | .0003" | 1.2500 ......... | .0014" |
.3750 ..... | .0005" | 1.5000 ......... | .0017" |
.5000 ..... | .0006" | 1.7500 ......... | .0020" |
.6250 ..... | .0008" | 2.000 to 5.000 .. | .0025" |
.7500 ..... | .0009" | over 5.000..... | .0005" |
.8750 ..... | .0010" | per inch of diameter | |
1.0000 . . .. | .0012" |
In orifice type meters the sharpness of the orifice edge shall be maintained in such a condition that the upstream edge of the orifice shall not appreciably reflect a beam of light when viewed without magnification. No meter which is mechanically defective shall be placed in service or allowed to remain in service after such defect has been discovered. The inlet and outlet of diaphragm type meters shall be capped when not connected in service.
Wis. Admin. Code Public Service Commission PSC 134.27