1 About EC350
1.3 Theory of Operation
Honeywell 2024
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1.3.2 Pressure Factor Fp
The pressure factor (Fp) to apply to metered volume is expressed by the Boyle’s Law relationship as
follows:
Each increment of meter pressure represents a different pressure factor. As the flowing gas pressure (Pm)
changes, the EC350 automatically applies the pressure factor (Fp) to the metered volume (Vm).
1.3.3 Temperature Factor Ft
The temperature factor (Ft) to apply to metered volume is expressed by the Charles’ Law relationship as
follows:
Each increment of meter temperature represents a different temperature factor. Therefore, as the flowing
gas temperature changes, the EC350 automatically applies the temperature factor (Ft) to the metered
volume.
1.3.4 Supercompressibiity Factor Fpv
Gases actually behave slightly different than what the ideal gas laws indicate. This deviation depends on
the molecular composition of the gas and the specific gravity as well as the pressure and temperature.
Natural gas, for instance, compresses by a greater amount than that computed by Boyle’s law and hence
the term “supercompressibility” is used for this deviation. It is small at very low pressure, but becomes
substantial as the pressure increases. The EC350 automatically applies the supercompressibility factor
and therefore the equation for total volume correction that the EC350 applies to metered volume, is
expressed as:
Where:
Vb = gas volume (cu. Ft.) at base condition corrected
Vm = metered volume read from meter index
Fp = pressure factor
Ft = temperature factor
Fpv = supercompressibility determined from NX-19 or AGA-8
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