Illinois Administrative Code
Title 83 - PUBLIC UTILITIES
Part 501 - STANDARDS OF SERVICE FOR GAS UTILITIES AND ALTERNATIVE GAS SUPPLIERS
Subpart B - NATURAL GAS MEASUREMENT REQUIREMENTS
Section 501.150 - Fixed Factor Delivery

a) A utility's regulator for fixed factor delivery shall control the delivery pressure at the outlet of the meter to ± 1% of the absolute billing pressure (delivery pressure (psi) + atmospheric pressure) over the range of expected regulator inlet pressures and customer load requirements. For example, for a 10 psig service and assuming an atmospheric pressure of 14.4 psi, the regulator shall control the delivery pressure at the outlet of the meter between 10.244 psig and 9.756 psig.

b) A utility may use fixed-factor delivery at delivery pressures of less than or equal to 15 psig. At pressures above 15 psig, a utility shall not use fixed factor delivery except for company-use metering that was in place on January 1, 2017.

c) A utility shall determine fixed factors for billing by measuring the pressure at the meter outlet with a calibrated pressure instrument while the regulator is delivering a steady flow to the meter, but at a flow rate that is less than 90% of the meter's capacity at the designated fixed-factor operating pressure.

d) Whenever a utility performs regulator or meter set maintenance that can affect the established fixed factor, the utility shall reestablish and reset the fixed factor if the reading falls outside of the allowable delivery pressure variations in subsection (a).

e) A utility shall verify that the regulator's delivery pressure meets the requirements of subsection (a) at least every 36 months. If a utility documents conditions at the meter that prevent verification, then the utility may delay verification until those conditions cease to exist or for four months, whichever is shorter. If a utility delays verification, it shall maintain for three years documentation of the conditions that prevented verification within the required 36 months and provide the documentation to an authorized representative of the Commission when requested.

f) A utility is not required to conduct the verification of the regulator's delivery pressure in subsection (e) for residential rate classes if those locations serve a customer at a pressure of 5.0 psi or less and the utility uses a meter with a rated capacity under 700 cubic feet per hour (at 1/2 inch differential) to measure the residential customer's usage.

g) A utility is not required to conduct the verification of the regulator's delivery pressure in subsection (e) for non-residential rate classes if those locations serve a customer at a pressure of 2.0 psi or less and the utility uses a meter with a rated capacity under 700 cubic feet per hour (at 1/2 inch differential) to measure the non-residential customer's usage.