Triple Point (chemicals.triple)¶
This module contains lookup functions for a chemical’s triple temperature and pressure. The triple temperature is the unique co-existence point between a pure chemicals’s solid, gas, and liquid state.
For reporting bugs, adding feature requests, or submitting pull requests, please use the GitHub issue tracker.
Triple Temperature¶
- chemicals.triple.Tt(CASRN, method=None)[source]¶
This function handles the retrieval of a chemical’s triple temperature. Lookup is based on CASRNs. Will automatically select a data source to use if no method is provided; returns None if the data is not available.
Returns data from [1], [2] or [3], or a chemical’s melting point if available.
- Parameters
- CASRN
str
CASRN [-]
- CASRN
- Returns
- Tt
float
Triple point temperature, [K].
- Tt
- Other Parameters
- method
str
,optional
A string for the method name to use, as defined in the variable, Tt_all_methods.
- method
See also
Notes
Median difference between melting points and triple points is 0.02 K. Accordingly, this should be more than good enough for engineering applications.
The data in [1] is originally on the ITS-68 temperature scale, but was converted to ITS-90. The numbers were rounded to 6 decimal places arbitrarily and the conversion was performed with this library.
References
- 1(1,2)
Staveley, L. A. K., L. Q. Lobo, and J. C. G. Calado. “Triple-Points of Low Melting Substances and Their Use in Cryogenic Work.” Cryogenics 21, no. 3 (March 1981): 131-144. doi:10.1016/0011-2275(81)90264-2.
- 2
Shen, V.K., Siderius, D.W., Krekelberg, W.P., and Hatch, H.W., Eds., NIST WebBook, NIST, http://doi.org/10.18434/T4M88Q
- 3
Huber, Marcia L., Eric W. Lemmon, Ian H. Bell, and Mark O. McLinden. “The NIST REFPROP Database for Highly Accurate Properties of Industrially Important Fluids.” Industrial & Engineering Chemistry Research 61, no. 42 (October 26, 2022): 15449-72. https://doi.org/10.1021/acs.iecr.2c01427.
Examples
Ammonia
>>> Tt('7664-41-7') 195.49
- chemicals.triple.Tt_methods(CASRN)[source]¶
Return all methods available to obtain the triple temperature for the desired chemical.
- Parameters
- CASRN
str
CASRN, [-]
- CASRN
- Returns
See also
- chemicals.triple.Tt_all_methods = ('HEOS', 'STAVELEY', 'WEBBOOK', 'MELTING')¶
Tuple of method name keys. See the Tt for the actual references
Triple Pressure¶
- chemicals.triple.Pt(CASRN, method=None)[source]¶
This function handles the retrieval of a chemical’s triple pressure. Lookup is based on CASRNs. Will automatically select a data source to use if no method is provided; returns None if the data is not available.
Returns data from [1], [2], or [3].
This function does not implement it but it is also possible to calculate the vapor pressure at the triple temperature from a vapor pressure correlation, if data is available; note most Antoine-type correlations do not extrapolate well to this low of a pressure.
- Parameters
- CASRN
str
CASRN [-]
- CASRN
- Returns
- Pt
float
Triple point pressure, [Pa]
- Pt
- Other Parameters
- method
str
,optional
A string for the method name to use, as defined in the variable, Pt_all_methods.
- method
See also
References
- 1
Staveley, L. A. K., L. Q. Lobo, and J. C. G. Calado. “Triple-Points of Low Melting Substances and Their Use in Cryogenic Work.” Cryogenics 21, no. 3 (March 1981): 131-144. doi:10.1016/0011-2275(81)90264-2.
- 2
Shen, V.K., Siderius, D.W., Krekelberg, W.P., and Hatch, H.W., Eds., NIST WebBook, NIST, http://doi.org/10.18434/T4M88Q
- 3
Huber, Marcia L., Eric W. Lemmon, Ian H. Bell, and Mark O. McLinden. “The NIST REFPROP Database for Highly Accurate Properties of Industrially Important Fluids.” Industrial & Engineering Chemistry Research 61, no. 42 (October 26, 2022): 15449-72. https://doi.org/10.1021/acs.iecr.2c01427.
Examples
Ammonia
>>> Pt('7664-41-7') 6053.386
- chemicals.triple.Pt_methods(CASRN)[source]¶
Return all methods available to obtain the Pt for the desired chemical.
- Parameters
- CASRN
str
CASRN, [-]
- CASRN
- Returns
See also
- chemicals.triple.Pt_all_methods = ('HEOS', 'STAVELEY', 'WEBBOOK')¶
Tuple of method name keys. See the Pt for the actual references