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BASIC GAS LAWS
MichaelMcCarthy
RegionalSales
Manager
GEMooney/Becker
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Understandingthe
Basic
Gas
Laws
Systemdesignandmaintenancearegoverned
bythe
physical
behavior
of
natural
gas.
Jobperformancerequiresknowledgeoftechnicallanguageoftheindustry.
SafetyisdirectlyrelatedtotheBasicGasLaws.
Customerserviceissuesandmeasurementaccuracy
require
proper
use
of
the
Basic
Gas
Laws.
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3BASIC
GAS
LAWS
BoylesLaw
(pressure)
Charles
Law
(temperature)
Supercompressibility(fudgefactor)
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BOYLESLAW
Ataconstanttemperature,thevolume
ofan
ideal
gas
decreases
when
an
increaseinpressureisapplied. (Wikipedia)
P1xV1 = P2xV2
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Atypicalscubatankcontainsapproximatelycubicfootvolume
displacementandcanbepressurizedupto4,000poundspersquare
inch.
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4TYPES
OF
PRESSURE
1) AtmosphericPressure affectedbyweatherand
altitude
2) GaugeorlinePressure pressureinthepipingsystem
3) AbsolutePressure sumofatmosphericplusgaugepressure
4) BasePressure arbitrarytariffvalue
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PRESSUREFACTOR
Anumberthatreflectsthechangeingas
volumethat
results
from
achange
in
pressure.
Atm.pressure(14.4)+linepressure(2)
= pf(1.113)
Basepressure(14.73)
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COMMONPRESSURE
FACTORS
PSIG Pf
1
1.045
2 1.113
5 1.317
10 1.656
20 2.335
30 3.01460 5.051
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MAOP
Maximum
Allowable
Operating
Pressure
(Governedbyavarietyoffactors,includingtheageand
typeofpipeinthesystem,typesofmetersand
regulatorsin
use,
physical
condition
of
the
piping,
maintenancehistory,andoperatinghistory.)
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CHARLESLAW
(temperature)
Ataconstantpressure,thevolumeofagiven
massof
an
ideal
gas
increases
or
decreases
by
thesamefactorasitstemperatureonthe
absolutetemperaturescale. (Wikipedia)
V1xT2 = V2xT1
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USEFULRULES
OF
THUMB
1) TemperatureconversionsaredoneinR
(Rankin)
2) R=F+460(e.g.60F=520R)
3) A5F
change
in
temperature
produces
a1%
changeinvolume.
4) Foreach
100psig
reduction
in
pressure,
temperaturedrops7F.
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SUPERCOMPRESSIBILITY
Therearenoidealgasesinthereal
world.
Highpressures
and
high
temperatures
causedeviationfromBoylesandCharlesLaw
calculations. At60psig,thesuper
compressibilityeffect
is
~1%;
at
higher
transmissionpressuresitcanbeover10%.
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COMMONGAS
DEFINITIONS
Cf : thevolumeofacontainerthatis1
tall,1
wide,
and
1
deep
Scf :
thevolume
of
acontainer
that
is
1
tall,1wide,and1deepata
constanttemperatureof60Fand
basepressure
conditions
of
14.73
psia.
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COMMONGAS
DEFINITIONS
Btu : Britishthermalunitrepresentsthe
amountof
heat
required
to
raise
the
temperatureofonepoundofwateronedegreeF.
Heat : 1scfofnaturalgascontains~1,028Value : Btus.
Therm:
=100,000
Btus,
which
is
~=
to100
cf
or1ccf
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FINALEXAM
QUESTION!!!
InwhatunitofvolumedoU.S.gasmeters
recordgas
consumption?
1) Cf cubicfeet
2) Scf standardizedcubic
feet
3) Ccf 100sofcubicfeet
4) Cm cubicmeters
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EXAMANSWER
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QUESTIONS?
