Illinois Administrative Code
Title 83 - PUBLIC UTILITIES
Part 501 - STANDARDS OF SERVICE FOR GAS UTILITIES AND ALTERNATIVE GAS SUPPLIERS
Subpart A - GENERAL
Section 501.10 - Definitions and Incorporations by Reference

a) Definitions

"Act" means the Public Utilities Act [ 220 ILCS 5 ].

"AGA" means the American Gas Association.

"Alternative Gas Supplier" has the same meaning as in Section 19-105 of the Act.

"ANSI" means the American National Standards Institute.

"Answer Time" means a measurement from the point the customer dialed the last digit of the natural gas public utility's or alternative gas supplier's telephone number and a natural gas public utility or alternative gas supplier representative or automated system is ready to render assistance or accept information to process calls.

"Auxiliary Equipment" means an integral device attached directly or remotely to a gas meter. The function of auxiliary equipment is to adjust gas meter usage measurements to account for changes in gas temperature or pressure.

"Bell Prover" means a cylindrical metal tank open at the top and nearly filled with liquid, in which a smaller calibrated cylindrical tank called the bell, open at the bottom and having a dome-shaped top, can be raised or lowered. As the operator raises (negative pressure) or lowers (positive pressure) the bell, the bell will displace a known volume of air.

"British Thermal Unit" or "BTU" means the quantity of heat required to raise the temperature of one pound of water one degree Fahrenheit from 58.5 °F to 59.5 °F under a standard pressure of 30 inches of mercury at 32°F, or 1054.804 Joules.

"Complaint" means an objection made to a natural gas public utility or alternative gas supplier, by a customer or another entity, as to its charges, facilities or service. Complaints include a customer or other entity identifying and asking a natural gas public utility or alternative gas supplier to address or resolve a problem or concern and shall not include contacts that are limited to inquiry or seeking information.

"Compressibility" means a gas volume correction factor calculated by using the parameters of natural gas composition, flowing gas temperature, and flowing gas pressure. The compressibility correction factor compensates for the deviation of gases from the ideal gas laws with increased pressure and with variations in temperature and gas composition. Compressibility is not to be confused with "supercompressibility", which is also defined in this Section.

"Coriolis Meter" means a gas meter that infers mass flow rate by measuring tube displacement resulting from the Coriolis effect.

"Corrector" means a device that corrects uncorrected gas meter volume according to the gas laws (Boyle's Law, Charles' Law, and Real Gas Law).

"Commission" means the Illinois Commerce Commission.

"Commission Referee Test" means the accuracy test of any gas meter made in the presence of one or more members of Commission Staff.

"Cubic Foot" means the unit of volume for purposes of measurement at a base temperature of 60°F at a base pressure of 14.73 pounds per square inch absolute.

"Custody Transfer Meter" means the meter, auxiliary equipment and tertiary equipment a utility uses to measure a customer's gas usage.

"Diaphragm Meter" means a positive displacement, bellows-type gas meter that alternately fills and empties compartments of known volume and totals the number of times the cycle occurs to determine the volume of gas passing through the meter.

"Defective Meter" means a meter whose condition is impairing service to a customer or a meter that has failed the requirements of Sections 501.170, 501.180, 501.190, 501.200, 501.210, 501.220 or 501.230.

"Flow Computer" means a device that electronically converts signals from a gas measurement system to a useful form such as flow rate.

"Fixed Factor" means the use of a gas pressure regulator to control gas pressure within an allowable pressure band over the required flow rate range considering the variation of inlet pressures and results in the application of a pressure correction factor applied via an arithmetic application or special index to a customer's measured usage.

"Master Bell" means a primary bell prover used as a reference standard for target proof correlations and bell prover interface recertification.

"Measurement Error" means an error in the calculation of a customer's gas usage due to the inaccuracy or improper setup of a utility's meter or other equipment whose function directly or indirectly affects the utility's measurement of a customer's gas usage.

"Meter Accuracy" means the overall performance of a particular meter in relationship to a known reference or portable standard.

"Meter Soaking Room" means a room maintained at the same atmospheric conditions as the meter proving room. The purpose of a meter soaking room is to store and acclimatize meters prior to testing to ensure meter testing accuracy that is not affected by temperature variations.

"Multi-path Ultrasonic Meter" means a device that derives gas flow rate by measuring the transit times of high-frequency sound pulses. Sound pulses transit between pairs of transducers located on or in the gas pipe.

"Natural Gas Supplier" means an alternative gas supplier or any other natural gas supplier providing the natural gas commodity to a customer under a gas utility tariff or rider.

"Orifice Meter" means an inferential meter that consists of an orifice plate perpendicular to the gas flow in a pipe. When gas flows across the orifice, it creates a pressure differential. Transmitters and transducers measure the pressure differential, static pressure, and other variables to determine the flow rate. The flow rate is proportional to the square root of the differential pressure across the orifice plate.

"Portable Standards" means instruments that utilities use in the field or the meter shop to test the accuracy of auxiliary and tertiary equipment, transmitters, and other equipment associated with correcting a meter's output.

"Proving Room" means a temperature-controlled room where the utility uses equipment to determine the accuracy of meters.

"Rated Capacity" or "Badged Capacity" means the hourly gas throughput of a meter as defined by the meter manufacturer.

"Reference Standards" means instruments that utilities use only for verifying the accuracy of portable standards, and whose accuracy is traceable back to the national standard maintained by the National Institute of Standards and Technology (NIST) or its successor.

"Rotary Meter" means a positive displacement meter that alternately fills and empties rotating compartments of known size and totals the number of times the cycle occurs to determine the volume of gas passing through the meter.

"Service Applicant" means a person who applies for residential or non-residential utility service for a location where the utility has not yet installed the meter.

"Small Commercial Customer" has the same meaning as in Section 19-105 of the Act.

"Sonic Nozzle Automatic Prover" means a device containing a parallel bank of sonic flow nozzles that it uses to determine actual gas volume passed through a gas meter in order to determine the gas meter's accuracy.

"Sub-metering" means the placement of a meter downstream of a custody transfer meter.

"Supercompressibility" means a value used in some flow equations for differential pressures (for example, orifice metering). In general, the supercompressibility factor is equal to the square root of the quotient of gas compressibility at base conditions divided by the gas compressibility at flowing conditions. Supercompressibility is not to be confused with "compressibility".

"Tertiary Equipment" means a device that electronically converts signals from a gas measurement system (meter or auxiliary equipment or both) to a useful form such as flow rate (for example, flow computers).

"Therm" means a unit of measurement representing a quantity of heat equivalent to 100,000 BTUs and expresses the energy content of natural gas.

"Transducer" means a sensing element capable of transforming values of physical properties such as pressure or temperature into equivalent electrical signals.

"Transmitter" means a device designed to enhance the transmission of information from a transducer to a flow computer by the addition of an electrical circuit that converts the transducer output to a standard signal in analog, digital or frequency form.

"Turbine Meter" means an inferential meter that measures gas flow by counting the revolutions of a rotor with blades, which turn in proportion to the gas flow velocity.

b) Incorporations by Reference. The following materials are incorporated by reference as of the date stated and include no later editions or amendments.

American Gas Association, 400 North Capitol Street, NW, Washington DC 20001

AGA Report No. 3, Orifice Metering of Natural Gas - Part 2: Specification and Installation Requirements, XQ0002 (April 2000)

AGA Report No. 7, Measurement of Natural Gas by Turbine Meter, XQ0601 (February 2006)

AGA Report No. 9, Measurement of Gas by Multipath Ultrasonic Meters, XQ0701 (April 1, 2007)

AGA Report No. 11, Measurement of Natural Gas by Coriolis Meter, XQ1301 (February 1, 2013)

AGA Gas Measurement Manuals - Part 15: Electronic Corrector, XQ9901 (May 1999)

AGA Gas Measurement Manuals - Part 8: Electronic Flow Computers and Transducers, Revised (1988), XQ8805 (May 1988)

American National Standards Institute and American Society for Quality (American National Standards Institute, 25 West 43rd Street, 4th Floor, New York, New York 10036)

Sampling Procedures and Tables for Inspection by Attributes, ANSI/ASQ Z1.4 -2008 (January 1, 2008)

American National Standards Institute and American Gas Association (American National Standards Institute, 25 West 43rd Street, 4th Floor, New York, New York 10036)

Diaphragm-Type Gas Displacement Meters (Under 500 Cubic Feet Per Hour Capacity), ANSI B109.1 -2000, AGA XQ0008 (June 2000)

Diaphragm-Type Gas Displacement Meters (500 Cubic Feet Per Hour Capacity and Over), ANSI B109.2 -2000, AGA XQ0009 (June 2000)

Rotary-Type Gas Displacement Meters, ANSI B109.3 -2000, AGA XQ0010 (June 2000)