Procedure. The following procedures shall apply to the testing and adjusting of meters and associated devices: General. The test of any unit of metering equipment shall consist of a comparison of its accuracy with the accuracy of a standard. Adjusted to Zero. All meters and associated devices, when tested, shall be adjusted as closely as practicable to the condition of zero error. Use of Tolerances. All tolerances are to be interpreted as maximum permissible variations from the condition of zero error. In making adjustments, no advantage of the prescribed tolerance limits may be taken. Test Flows. For determination of minimum test flow and other normal test flows, the Commission will use as a guide the appropriate standard specifications of the American Water Works Association for the various types of meters. These flows for displacement type cold water meters are as follows: Tests to Determine Error in Registration. Meters shall be tested at the following three flows: Minimum test flow; Approximately 10 percent of the maximum normal flow; Approximately 50 percent of the maximum normal flow, or at the maximum flow available at normal system pressure.