الظروف القياسية لدرجة الحرارة والضغط

تتغير قيم درجة الحرارة والضغط من مكان لأخر على سطح الأرض ، كما يمكن حتى تتغير في نفس المكان مع الوقت . وهذه القيم هامة للغاية في عمليات كيميائية وفيزيائية عديدة . وعلى هذا فإنه من المهم تعريف ظروف ضغط وحرارة قياسية .

يكون التعبير بظروف الضغط والحرارة القياسية (standard temperature and pressure) وإختصاره STP يعنى بالتحديد درجة حرارة صفر°C وضغط 1 atm ( أو101.325 kPa ) . وهذه القيم هى تقريبا درجة تجمد الماء تحت الضغط الجوى عند مستوى سطح البحر .

كما حتى التعبير بظروف الضغط والحرارة القياسية المحيطة (standard Ambient temperature and pressure) وإختصاره SATP يعنى بالتحديد درجة حرارة 25°C أى ( 298.15 K ) وضغط 100 kPa . وبالرغم من وجود عدة إختلافات للتعبير عن الظروف القياسية ، فإن الظروف الأكثر قبولا هى درجة الحرارة والضغط التىقد يكون عندها ثابت تأين الماء 1.0 × 10⁻¹⁴ .

ويستخدم المقياس الأساسي الحربي فقط في دراسة القذائف ، والذىقد يكون فيه مستوى سطح البحر مساولـ 750 مم زئبق ( 29.5275 بوصة زئبق ) و( 99.9918 kPa ) و59°F أى (15°C ) و78 % رطوبة .

بينما قامت المنظمة الدولية للطيران المدني (International Civil Aviation Organization وإختصارها (ICAO) بتعريف مستوى سطح البحر على أساس المعيار الدولي للغلاف الجوي ( International Standard Atmosphere ) وإختصاره (ISA) على أنه 101.325 kPa و15°C وصفر % رطوبة . وهذه القيم تعتبر مرجعية عند دراسة أداء الطائرات مثل سرعة الهواء وإستهلاك الوقود . وعند دراسة اى متغير عند ضغط مغاير لمستوى سطح البحر يتم ضبط معدلات درجة الحرارة بحيث تكون - 6.5 C°/km لأول 11 كم .

التعريفات

الاستخدام الحالي

Standard reference conditions in current use
Temperature		Pressure				Humidity (%)	Publishing or establishing entity
°C	°F	kPa	mmHg	psi	inHg	Humidity (%)	Publishing or establishing entity
0	32	100.000	750.06	14.5038	29.530		IUPAC (STP) since 1982
0	32	101.325	760.00	14.6959	29.921		NIST, ISO 10780, formerly IUPAC (STP) until 1982
15	59	101.325	760.00	14.6959	29.921	0	ICAO's ISA, ISO 13443,EEA, EGIA (SI Definition)
20	68	101.325	760.00	14.6959	29.921		EPA,NIST. This is also called NTP, Normal Temperature and Pressure.
22	72	101.325	760.00	14.6959	29.921	7001200000000000000♠20–80	American Association of Physicists in Medicine
25	77	100.000	750.06	14.5038	29.530		IUPAC (SATP)
25	77	101.325	760.00	14.6959	29.921		EPA
20	68	100.000	750.06	14.5038	29.530	0	CAGI
15	59	100.000	750.06	14.5038	29.530		SPE
20	68	101.3	760	14.69	29.9	50	ISO 5011
20	68	101.33	760.0	7005101325014435400♠14.696	7005101325014435400♠29.92	0	GOST 2939-63
16	60	101.33	760.0	14.696	7005101325353180402♠29.92		SPE, U.S. OSHA,SCAQMD
16	60	101.6	762	14.73	7005101559774928369♠30.0		EGIA (Imperial System Definition)
16	60	101	760	14.7	7005101352932209574♠30		U.S. DOT (SCF)
15	59	99.99	750.0	14.503	7004999946650228207♠29.53	78	U.S. Army Standard Metro
15	59	101.33	760.0	14.696	7005101325353180402♠29.92	60	ISO 2314, ISO 3977-2
21	70	101.3	760	14.70	29.92	0	AMCA, air density = 0.075 lbm/ft³. This AMCA standard applies only to air; Compressed Gas Association [CGA] applies to industrial gas use in USA
15	59	101.3	760	14.70	29.92		Federal Aviation Administration (FAA)
20	68	101.325	760.00	14.6959	29.921	0	EN 14511-1:2013
15	59	101.325	760.00	14.6959	29.921	0	ISO 2533:1975 ISO 13443:2005, ISO 7504:2015
0	32	101.325	760.00	14.6959	29.921	0	DIN 1343:1990

ملاحظات:

EGIA: Electricity and Gas Inspection Act (of Canada)
SATP: Standard Ambient Temperature and Pressure

انظر أيضاً

Atmospheric models
Environmental chamber
ISO 1 – standard reference temperature for geometric product specifications
Standard Dry Air
Standard state
Standard sea level
درجة حرارة الغرفة

تعليقات

^ The pressure is specified as 750 mmHg. However, the mmHg is temperature-dependent, since mercury expands as temperature goes up. Here the values for the 0–20 °C range are given.
^ The standard is given as 29.92 inHg at an unspecified temperature. This most likely corresponds to a standard pressure of 101.325 kPa, converted into ~29.921 inHg at 32 °ف (0 °م).

مراجع

^ A. D. McNaught and A. Wilkinson (1997). (2nd ed.). Oxford: Blackwell Scientific Publications. doi:10.1351/goldbook.S06036. ISBN . Standard conditions for gases: ... and pressure of 10⁵ pascals. The previous standard absolute pressure of 1 atm (equivalent to 101.325 kPa) was changed to 100 kPa in 1982. IUPAC recommends that the former pressure should be discontinued.
^ NIST (1989). "NIST Standard Reference Database 124 – Stopping-Power and Range Tables for Electrons, Protons, and Helium Ions". Archived from the original on October 6, 2010. Retrieved 2008-07-25. If you want the program to treat the material as an ideal gas, the density will be assumed given by M/V, where M is the gram molecular weight of the gas and V is the mol volume of 22414 cm³ at standard conditions (0 deg C and 1 atm).
^ ISO (1994). "ISO 10780:1994 : Stationary source emissions – Measurement of velocity and volume flowrate of gas streams in ducts".
^ . Geneva, Switzerland: International Organization for Standardization. 1996.
^ Robert C. Weast (Editor) (1975). Handbook of Physics and Chemistry (56th ed.). CRC Press. pp. F201–F206. ISBN .CS1 maint: extra text: authors list (link)
^ (PDF). Copenhagen, Denmark: European Environmental Agency. September 1999. ^[]
^ "Electricity and Gas Inspection Act", SOR/86-131 (defines a set of standard conditions for Imperial units and a different set for metric units) Canadian Laws.
^ "Standards of Performance for New Sources", 40 CFR—Protection of the Environment, Chapter I, Part 60, Section 60.2, 1990 New Source Performance Standards^[].
^ Wright, J. D.; Johnson, A. N.; Moldover, M. R. (2003). "Design and Uncertainty for a PVTt Gas Flow Standard" (PDF). Journal of Research of the National Institute of Standards and Technology. 108 (1): 21–47. doi:10.6028/jres.108.004. PMC 4844527. PMID 27413592. Archived from the original (PDF) on 2004-07-21.
^ "What is the difference between STP and NTP?". Socratic. Archived from the original on 2015-11-27. Retrieved 2018-08-28.
^ Almond, Peter R.; Biggs, Peter J.; Coursey, B. M.; Hanson, W. F.; Huq, M. Saiful; Nath, Ravinder; Rogers, D. W. O. (1999). "AAPM's TG-51 protocol for clinical reference dosimetry of high-energy photon and electron beams". Medical Physics. 26 (9): 1847–1870. Bibcode:1999MedPh..26.1847A. doi:10.1118/1.598691. PMID 10505874.
^ "National Primary and Secondary Ambient Air Quality Standards", 40 CFR—Protection of the Environment, Chapter I, Part 50, Section 50.3, 1998 National Ambient Air Standards^[].
^ "Glossary". Cleveland, OH, USA: Compressed Air and Gas Institute. 2002. Archived from the original on 2007-09-02.
^ "The SI Metric System of Units and SPE Metric Standard (1982)" (PDF). Society of Petroleum Engineers. Standard Temperature (Page 24), and Notes for Table 2.3, (on PDF page 25 of 42 PDF pages), define two different sets of reference conditions, one for the standard cubic foot and one for the standard cubic meter.
^ . Geneva, Switzerland: International Organization for Standardization. 2002.
^ "Storage and Handling of Liquefied Petroleum Gases" and "Storage and Handling of Anhydrous Ammonia", 29 CFR—Labor, Chapter XVII—Occupational Safety and Health Administration, Part 1910, Sect. 1910.110 and 1910.111, 1993 Storage/Handling of LPG.
^ "Rule 102, Definition of Terms (Standard Conditions)", Amended December 2004, South Coast Air Quality Management District, Los Angeles, California, USA SCAQMD Rule 102^[]
^ "49 C.F.R. § 171". Retrieved 22 May 2018.
^ Sierra Bullets. "Chapter 3 – Effects of Altitude and Atmospheric Conditions (Exterior Ballistics Section)". Rifle and Handgun Reloading Manual (5 ed.). Sedalia, MO, USA.
^ (2 ed.). Geneva, Switzerland: International Organization for Standardization. 1989.
^ . Geneva, Switzerland: International Organization for Standardization. 1997.
^ ANSI/AMCA Standard 210, "Laboratory Methods Of Testing Fans for Aerodynamic Performance Rating", as implied by http://www.greenheck.com/pdf/centrifugal/Plug.pdf when accessed on October 17, 2007.
^ Association, Compressed Gas (2012-12-06). . ISBN . Retrieved 22 Nov 2017.
^ "Chapter 3, Principles of Flight" (PDF). Pilot's Handbook of Aeronautical Knowledge. Federal Aviation Administration. ^[]
^ . UK: BSI EN. 2013.
^ . Geneva, Switzerland: International Organization for Standardization. 1975.
^ . Geneva, Switzerland: International Organization for Standardization. 1996.
^ . Geneva, Switzerland: International Organization for Standardization. 2015.
^ . Germany: Deutsches Institut für Normung. 1990.

مصادر

Alan D. McNaught, Andrew Wilkinson (eds.) (1997). IUPAC Compendium of Chemical Terminology (the “Gold Book”). Second revised edition. Blackwell Scientific, Oxford. ISBN 978-0-9678550-9-7
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