Meter Shop. Each utility shall maintain or designate a meter shop where meters may be inspected, tested, and repaired. The shop shall be open for inspection by authorized representatives of the Commission at all reasonable times, and the facilities and equipment, as well as the methods of making measurements and tests, shall be subject to the approval of the Commission. Accuracy of Test Equipment. The accuracy of the test equipment and of the test procedures shall be such that the overall error will not exceed 0.3 of 1 percent. Requirements. Each meter shop maintained or designated by a utility shall have at least one calibrated tank for volumetric measurement or a tank mounted upon scales for weight measurement. The tank shall be of sufficient capacity to insure an acceptable determination of the accuracy of the utilities' meters. Calibration. Working standards shall be checked periodically (see Regulation .09B of this chapter) by comparison with approved secondary standards. Certificates. Each standard shall be accompanied at all times by a certificate or calibration card, duly signed and dated, on which are recorded the corrections required to compensate for errors found at the customary test points at the time of the last previous test. Care in Handling. Extreme care shall be exercised in the use and handling of standards to assure that their accuracy is not disturbed. 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. Pre-Installation Tolerances. A meter may not be placed in service if it registers less than 90 percent of the water passed through it at the minimum test flow or over-registers or under- registers more than 1-1/2 percent at the other test flows. Calculation of Error. The percentage by which the correct registration varies from the meter registration is derived by stopping the meter test hand at the starting point and then determining the percentage variation in registration as indicated by the working standard. The formula for determining the percentage error in registration is: Error in Registration for Billing Adjustments. The error in registration of a meter for billing adjustments shall be the algebraic average of the error in registration at the following two rates of flow: Approximately 10 percent of maximum normal flow; Approximately 50 percent of maximum normal flow, or at the maximum flow available at normal system pressure. Application of Error for Billing Adjustments. The meter error derived in §C, of this regulation, shall be used to calculate the correct consumption of water by applying the derived error in registration to the volume of water consumption indicated by the meter. If the meter is fast then the volume of water indicated by the meter registration shall be reduced by applying the calculated error in registration. If the meter is slow then the volume of water indicated by the meter registration shall be increased by applying the calculated error in registration. Approval. A meter may not be placed in service unless: Its type and design first has been approved by the Commission; It has been inspected and tested by the utility, or has been certified by the manufacturer to be correct; Its registration is within the tolerances specified in Regulation .04A of this chapter; and It has been sealed by the utility. Re-Installation. When any meter is removed from service it shall be repaired if necessary so that it conforms to the registration tolerances specified in Regulation .04A before being placed in service again. Request For Test. Upon request by a customer and at no charge, the utility shall make a test of the accuracy of registration of the meter serving the customer, provided that these tests need not be made more frequently than once in 24 months. Customer May Observe. The customer, or his representative, may be present when the meter is tested. Report to Customer. A report of the results of the test shall be made to the customer within a reasonable time after the completion of the test, and a record of the report, together with a complete record of the test, shall be kept on file at the office of the utility for at least 3 years. Application For Test. Upon written application to the Commission by a customer or a utility, a test will be made of the customer's meter as soon as practicable by a representative of the Commission. Deposit For Test. The application shall be accompanied by a deposit as indicated: Water meter—$10. Notice to Utility. On receipt of a request from a customer the Commission will notify the utility and the utility may not knowingly remove or adjust the meter until instructed by the Commission. The utility shall furnish to the Commission's representative such reasonable assistance as may be required to make the test. Customer May Observe. The customer, or his representative, may be present when the meter is tested. Report to Customer. A written report of the results of the test will be sent to the customer and to the utility. Disposition of Deposit. If the meter is found to over-register more than 2 percent, calculated in accordance with Regulation .04C, the deposit shall be refunded by the Commission and the utility billed the amount of the deposit. Otherwise the deposit will be retained and disposed of according to law. Each meter shall be tested before the meter is adjusted or repaired. Each utility shall make periodic tests of meters and standards to assure their accuracy. These tests shall be scheduled within the calendar year, or earlier, when the interval is stated in years, or within the calendar month, or earlier, when the interval is stated in months. The basic periodic test interval may not be longer than provided for in the following schedule: (Note: Maintenance programs suggested by manufacturers of the following meters and devices should be carefully followed.) Meters. 5/8 in. ------------------------------10 years 3/4 in. ------------------------------ 8 years 1-in. -------------------------------- 6 years 1-1/2 in. and 2-in. ------------------4 years 3-in. and 4-in. ----------------------2 years 6-in. and larger --------------------12 months Working Standards. Volumetric tank ---------------------- 5 years Scales ------------------------------ 12 months Public Utilities Article, §§2-121, 5-101, and 5-303, Annotated Code of Maryland Effective date: July 1, 1968 (Order No. 57171) Regulation .07B amended effective April 13, 1992 (19:7 Md. R. 747) Regulation .08 amended effective May 14, 2001 (28:9 Md. R. 889)