Filter
Top Products
6 Micro Motion 3098 Gas Specific Gravity Meter
Introduction
1.4.2 Standard (base or normal) density
Standard (base or normal) density (
ρ
s
) is the absolute density of a gas at standard (base or normal)
conditions of temperature and pressure and is commonly used for standard volumne flow
determination from mass flow measurement.
1.4.3 Relative density
Relative density (
ρ
r
) is the ratio of the weight of a volume of gas (or gas mixture) to the weight of an
equal volume of dry air (see Table 1-1), where the weights of both gas
(or gas mixture) and air are
taken under identical conditions of temperature and pressure.
Note: Except for the effects of Boyle’s Law deviation upon both the gas (or gas mixture) and the air, G
and
ρ
r are synonymous.
The relative density of mixed hydrocarbon gases at 1 bar (14.50377 lb/in
2
) absolute and 15.56°C
(60°F) by empirical equation is:
for example
where p = absolute pressure (bars)
T = absolute temperature (degrees Kelvin)
M = molecular weight
Z = supercompressibility factor
R = gas constant (taken as 0.0831434)
ρ
s
pM
ZRT
------------=
for example
where ρ
G
= density of the gas or gas mixture
ρ
A
= density of air
Z
G
= supercompressibility factor of the gas or gas mixture
Z
A
= supercompressiblity factor of air
G
M
G
M
A
--------=
ρ
G
Z
G
ρ
A
Z
A
---------------=
ρ
r
Z
G
Z
A
-------
⋅=
ρ
r
0.995899G 0.010096G
2
+=