About Gas Quality Information

California Gas Transmission continuously monitors gas quality at selected points on its system using the gas SCADA system. For customer convenience, daily snapshots of this information are available on Pipe Ranger. To view these snapshots of gas quality data for a particular customer, find and click on the customer's Btu area on the Gas Quality Information page.


For most Btu areas, Pipe Ranger provides the Btu content, specific gravity (relative density), and gas composition data (mole percent for carbon dioxide, nitrogen, etc.). The level of detail available varies from area to area.


Gas quality data is not monitored on a real time basis in all Btu areas so information for some locations is not available. Sample data is gathered around 10 a.m. daily. CGT uses this data for operational purposes but generally not for billing or OFO compliance monitoring. Please read the important disclaimer below.



Btu Content

Also known as higher heating value, Btu content is Btus per standard cubic foot measured on a dry basis at 14.730 PSIA and 60 Degrees Fahrenheit.


Btu Area

Btu areas are geographic areas where customers receive a uniform gas quality. Btu areas are also used in the billing process. The Pacific Gas and Electric Company billing system uses data from the Therm Factor Table to calculate the gas energy delivered to customers in each Btu area.


Gas Composition

In addition to the Btus and specific gravity, carbon dioxide (CO2) and nitrogen (N2) content are available for most areas. In a few areas, methane, ethane, propane, I-butane, N-butane, I-pentane, N-pentane, and C6+ content are also available. These measurements are all in mole percent.


Specific Gravity

The specific gravity is the density of the gas mixture relative to air.



Disclaimer: The data on these pages is a representative sample of gas quality information only. It is raw, unreviewed, real-time data provided solely for informational purposes, and not for billing purposes. Pacific Gas and Electric Company makes no claim or representation that the data provided is accurate. No party should rely on such data, including, but not limited to, for billing purposes. Data may be subject to adjustments and corrections prior to being used for billing or record keeping.