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Portland Natural Gas Transmission System   Original Sheet No. 320 : Effective
FERC Gas Tariff
Portland Natural Gas Transmission System


                   GENERAL TERMS AND CONDITIONS (Continued)
   
  6.   MEASUREMENT OF GAS AND MEASUREMENT EQUIPMENT
   
       6.1 The volume and the Total Heating Value of the Gas made available
to Transporter at the Receipt Point(s) and made available to or on behalf of
Shipper at the Delivery Point(s) shall be determined as follows:
   
            (a)  Unit of Measurement.  The unit of Gas, for the purpose of
measurement, shall be one (1) Mcf.
   
            (b)  Heating Value per Cubic Foot.  The Total Heating Value of the
Gas per Cubic Foot shall be determined for any Month by taking the weighted
average of the heating values as recorded each Day by an on-line gas
chromatograph or as determined by chromatographic analysis of a sample of Gas
collected Daily during the Month, or any other method mutually agreed upon by
Shipper and Transporter.
   
            (c)  Determination of DTH Delivered.  The DTH delivered shall be
determined by multiplying the Mcf delivered by the ratio of the BTU per Cubic
Foot delivered to 1,000.  For purposes of this determination, the specific
gravity (relative density) and heating value shall be determined at the same
time, as described in Section 6.1(b) herein.
   
            (d)  Determination of Temperature.  The temperature of the Gas
passing through each meter shall be determined for any Day by the continuous
use of a recording thermometer so installed that it may properly record the
temperature of the Gas flowing through each meter.  The arithmetical average
of the temperature recorded each Day shall be used in computing Gas
quantities.  Where electronic gas measurement is used, live flowing
temperature values shall be used.
   
            (e) Specific Gravity.  The specific gravity of the Gas shall be
determined by the use of a recording gravitometer, which shall be checked by
Transporter at least once each Month, or any other method mutually agreed upon
by Shipper and Transporter.
   
            (f)  Deviation from Boyles Law.  The deviation of the Gas from
Boyles Law shall be determined by the use of the table of formulas published
by the American Gas Association Par Research Project NX-19 corrected for
carbon dioxide and nitrogen, or any superseding applicable tables or
calculation methods published by the American Gas Association.  Determinations
of the molecular percentage of N2 and CO2 in the Gas shall be made within
thirty (30) Days after







Issued by: David J.Haag, Rates And Tariff Specialist
Issue date: 07/28/06 Effective date: 09/01/06