Problem Statement

What is the standard state for volume?

Solution

The standard state for vapor and liquid volume are different. In addition, vapor volume can depend on the units.

Standard State for Vapor Volume

Standard vapor volume flows are entered on streams as MOLE flows by choosing the appropriate units.

Standard conditions are ideal gas at 1 atm and 0. C for SI and MET units. 0. C , 1 atm ---- 22.414 m3/kg-mol (or 359.03 cuft/lbmol)

Standard conditions are ideal gas at 14.696 psi and 60F for ENG units. 60.F , 14.696 psi ---- 379.49 cuft/lbmol (or 23.69 m3/kg-mol)

For example:
MMSCF - Million standard cubic feet. Standard conditions are ideal gas at 14.696 psi and 60. deg F.

MMSCFD - Million standard cubic feet/day. Standard conditions are ideal gas at 14.696 psi and 60. deg F.

MMSCFH - Million standard cubic feet/hour. Standard conditions are ideal gas at 14.696 psi and 60. deg F.

MMSCM - Million standard cubic meters. Standard conditions are ideal gas at 1 atm and 0. C.

MMSCMH - Million standard cubic meters/hour. Standard conditions are ideal gas at 1 atm and 0 C.

MSCFD - Thousand standard cubic feet/day. Standard conditions are ideal gas at 14.696 psi and 60 deg F.

MSCF - Thousand standard cubic feet. Standard conditions are ideal gas at 14.696 psi and 60 degF

NCMH - Normal cubic meters (identical to standard cubic meters)/hour. Standard conditions are ideal gas at 1 atm and 0. C.

NCMD - Normal cubic meters (identical to standard cubic meters)/day. Standard conditions are ideal gas at 1 atm and 0. C.

SCFM - Standard cubic feet/minute. Standard conditions are ideal gas at 14.696 psi and 60. deg F.

SCM - Standard cubic meters. Standard conditions are ideal gas at 1 atm and 0. C.

SCMH - Standard cubic meters/hour. Standard conditions are ideal gas at 1 atm and 0. C.

There are property sets that can be used to report the standard vapor volume for a stream. These property sets are all at 0 C and 1 atm unless the temperature and/or pressure is otherwise specified on the Prop-Sets\Qualifiers sheet.

•  VVSTD - Pure Component Standard Vapor Volume
•  VVSTDMX - Mixture Standard Vapor Volume
•  VVSTDFR - Standard Vapor Volume Fraction

In addition, it is possible to use a mole flow property set with one of the standard vapor volume flow unit sets such as SCFM or SCMH. The conditions are the standard conditions of the units as listed above.

• MOLEFLOW - Pure Component Mole Flow
• MOLEFLMX - Mixture Mole Flow
• MOLEFRAC - Mole Fraction

Standard State for Liquid Volume

Standard liquid volume flows are entered on streams as STDVOL flows.

Standard volume conditions are 60 deg F, 1 atm ( 14.696 psia )

There are property sets that can be used to report the standard liquid volume for a stream. These property sets are all at 60 deg F and 1 atm.

• VLSTD - Pure Component Standard Liquid Volume
• VLSTDMX - Mixture Standard Liquid Volume
• VLSTDFR - Standard Liquid Volume Fraction

Note

In Aspen Plus 11.1 and earlier, when using the some of the stream formats (e.g. GAS_E or AIR_M), the stream summary indicates that the standard vapor volume is at 60 deg F. This is incorrect. It is at 0 C.

KeyWords

Standard State
Volume
Unit of Measure