AGA 8 – Gas Density Computation


Form: K141 – AGA 8 – Gas Density Computation 85/94

Form Reference: C156

Calculation Details


The purpose of this test is to verify that the density is being correctly calculated by the flow computer.

Test Equipment

No test equipment is needed for this test to be carried out.


In this example the 1994 version of the AGA 8 standard is used.

Here the option is selected so that neo-pentane, if included in the composition, will be added to i-pentane.


The pressure and temperature at base and line conditions as well as the gas composition need to be input.

When setting up the form it is good practice to fix the base conditions so they can not be altered in error and to set the components to “User Entry With Default” as this means values that are zero or not represented in the composition do not need to be explicitly entered as zero every time a test is run. If using a fixed composition it would make sense to enter that while setting up the test so to avoid repeating the task and risk typing errors.


This form has several outputs.

The error mode will be percentage of calculated value.

The source type here is set as user entry, however, if the FM² system is set up to do so, OPC Server can be selected to automatically read the value being used by the flow computer.

The units are set as kg/m³ as default for density and compressibilities should be shown as decimal numbers.

The typical tolerance for this test is 0.001 %.

Outputs that are not needed to be displayed can be removed in the test form by clicking Manage on the Outputs section of the Configuration ribbon.