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RUSKA 2465A-754
Users Manual
A-6
EQUATION A-4
Air Density
Air Density (
ρ
air
) in units of g/cm
3
, is calculated as follows;
( ) ( )
( ) ( )
( )
t e x U x P x
t
air
+ − =
+ −
15 . 273 / 6 . 4990221 0004646 . 0
15 . 273 / 56 . 5315
ρ
where:
P = Barometric Pressure, (mmHg)
t
= Air Temperature, (ºC)
U = Relative Humidity, (%RH)
Nitrogen Density - English Units (0 to 1000 PSIG)
To calculate the density of Nitrogen at pressures from 0 psig to 1000 psig, use the
following equation;
( ) ( )
P x x in lbm DENSITY
6 3
10 826 . 2 /
− =
where;
PRESSURE P
=
in psi absolute (if
P
is in gauge, convert it to an absolute
value by adding barometric pressure, e.g.
7 . 14
+
P
)
Nitrogen Density - English Units (1,000 to 15,000 Psig)
To calculate the density of Nitrogen at pressures from 1,000 psig to 15,000, use the
following equation;
( ) ( ) ( ) ( )
2 11 6 4 3
10 46069 . 9 10 74396 . 2 10 37465 . 2 / P x P x x in lbm DENSITY
− − −
− + =
where;
PRESSURE P
=
in psi absolute (if P is in gauge, convert it to an absolute value
by adding barometric pressure, e.g.
7 . 14
+
P
)
Nitrogen Density - SI Units (0 to 6.9 MPa)
To calculate the density of Nitrogen at pressures from 0.01 MPa gauge to 6.9 MPa, use
the following equation;
( )
P x E m kg DENSITY 05 1347 . 1 /
3
− =
where;
PRESSURE P
=
in Pa absolute (if P is in gauge, convert it to Pa absolute by
adding barometric pressure, e.g.
101325
+
P
)