Honeywell Mini-AT User Manual

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Page 14
Mini-AT User Guide
Supercompressibility Factor Fpv
Gases actually behave in a manner slightly different from 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 Mini-AT automatically applies the
supercompressibility factor and therefore the equation for total volume correction which the Mini-AT
applies to metered volume, is expressed as:
Vb = Vm x Fp x Ft x (Fpv)
2
Where: Vb = volume corrected to base conditions
Vm = metered volume read from the meter index
Fp = pressure factor
Ft = temperature factor
Fpv = supercompressibility factor determined from AGA 3 /
NX-19 or AGA 8, from the AGA Manual for Determina-
tion of Supercompressibility Factors for Natural Gas. The
values of Fpv are derived in the tables for use with orifice
meters, which are square root function measurements. So
the flow equation for linear volume meters must square the
value of Fpv.
The Mini-AT automatically squares the supercompressibility factor displayed, which is based on the
pressure and temperature sensed at the meter. The resulting volume readout is corrected for pres-
sure, temperature, and supercompressibility.

Honeywell Mini-AT Specifications

General

Brand	Honeywell
Model	Mini-AT
Category	Controller
Language	English