Pressure Base Conversions

Natural gas volumes or Btu Factors (Heating Values) can be converted from one pressure base to another pressure base using the following formulas or conversion factors shown in Table 1 and Table 2 below.

General Rule: An MMBtu is an MMBtu regardless of the pressure base. Accordingly, as the pressure base increases, the natural gas volume (Mcf) decreases and the Btu Factor increases.

Formula Definitions:

P_F = pressure base at which volume or Btu factor is being converted from

P_T = pressure base at which volume or Btu factor is being converted to

Volume Conversion Formula:

Mcf@P_F times (P_F divided by P_T) = Mcf@P_T

TABLE 1 - Conversion factors for converting Mcf volume from one pressure base to a different pressure base.

From Pressure Base of

To Pressure Base of

14.65

14.696

14.73

15.025

14.65

1.000000

0.996870

0.994569

0.975042

14.696

1.003140

1.000000

0.997692

0.978103

14.73

1.005461

1.002314

1.000000

0.980366

15.025

1.025597

1.022387

1.020027

1.000000

Volume Conversion Calculation Examples:

1000Mcf @14.65 times (14.65 divided by 14.73) = 995Mcf @14.73

1000Mcf @14.65 times .994569 = 995 Mcf @14.73

Heating Value Conversion Formula:

Btu@P_F times (P_T divided by P_F) = Btu@P_T

TABLE 2 - Conversion factors for converting heating values (Btu factors) from one pressure base to a different pressure base. Note: the factors in Table 2 are the inverse (or reciprocals) of the factors shown in Table 1 (i.e. 1 divided by the Table 1 factor equals the Table 2 factor).

From Pressure Base of

To Pressure Base of

14.65

14.696

14.73

15.025

14.65

1.000000

1.003140

1.005461

1.025597

14.696

0.996870

1.000000

1.002314

1.022387

14.73

0.994569

0.997692

1.000000

1.020027

15.025

0.975042

0.978103

0.980366

1.000000

Heating Value Calculation Examples:

1010Btu/Cf @14.65 times (14.73 divided by 14.65) = 1016Btu/Cf @14.73

1010Btu/Cf @14.65 times 1.005461 = 1016Btu/Cf @14.73