الظروف القياسية لدرجة الحرارة والضغط

تتغير قيم درجة الحرارة والضغط من مكان لأخر على سطح الأرض ، كما يمكن أن 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 ( أو 101.325 kPa ) . وهذه القيم هى تقريبا درجة تجمد الماء تحت الضغط الجوى عند مستوى سطح البحر .

كما أن 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 التى يكون عندها ثابت تأين الماء 1.0 × 10−14 .

ويستخدم المقياس الأساسي الحربي فقط في دراسة القذائف ، والذى يكون فيه مستوى سطح البحر مساو لـ 750 مم زئبق ( 29.5275 بوصة زئبق ) و ( 99.9918 kPa ) و 59°F أى (15°C ) و 78 % 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 و 15°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 .

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التعريفات

الاستخدام الحالي

Standard reference conditions in current use
Temperature Pressure Relative
Humidity
(%) 		Publishing or establishing entity
°C °F kPa mmHg psi inHg
0 32 100.000 750.06 14.5038 29.530   IUPAC (STP) since 1982[1]
0 32 101.325 760.00 14.6959 29.921   NIST,[2] ISO 10780,[3] formerly IUPAC (STP) until 1982[1]
15 59 101.325 760.00 14.6959 29.921 0[4][5] ICAO's ISA,[5] ISO 13443,[4] EEA,[6] EGIA (SI Definition)[7]
20 68 101.325 760.00 14.6959 29.921   EPA,[8] NIST.[9] This is also called NTP, Normal Temperature and Pressure.[10]
22 72 101.325 760.00 14.6959 29.921 20–80 American Association of Physicists in Medicine[11]
25 77 100.000 750.06 14.5038 29.530   IUPAC (SATP)
25 77 101.325 760.00 14.6959 29.921   EPA[12]
20 68 100.000 750.06 14.5038 29.530 0 CAGI[13]
15 59 100.000 750.06 14.5038 29.530   SPE[14]
20 68 101.3 760 14.69 29.9 50 ISO 5011[15]
20 68 101.33 760.0 14.696 29.92 0 GOST 2939-63
16 60 101.33 760.0 14.696 29.92   SPE,[14] U.S. OSHA,[16] SCAQMD[17]
16 60 101.6 762 14.73 30.0   EGIA (Imperial System Definition)[7]
16 60 101 760 14.7 30   U.S. DOT (SCF)[18]
15 59 99.99 750.0 14.503 29.53 78 U.S. Army Standard Metro[19][أ]
15 59 101.33 760.0 14.696 29.92 60 ISO 2314,[20] ISO 3977-2[21]
21 70 101.3 760 14.70 29.92 0 AMCA,[22][ب] air density = 0.075 lbm/ft3. This AMCA standard applies only to air;
Compressed Gas Association [CGA] applies to industrial gas use in USA[23]
15 59 101.3 760 14.70 29.92   Federal Aviation Administration (FAA)[24]
20 68 101.325 760.00 14.6959 29.921 0 EN 14511-1:2013[25]
15 59 101.325 760.00 14.6959 29.921 0 ISO 2533:1975[26] ISO 13443:2005[27], ISO 7504:2015[28]
0 32 101.325 760.00 14.6959 29.921 0 DIN 1343:1990[29]


ملاحظات:

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

انظر أيضاً

تعليقات

  1. ^ 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.
  2. ^ 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 °F (0 °C).

مراجع

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  2. ^ 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).
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  10. ^ "What is the difference between STP and NTP?". Socratic. Archived from the original on 2015-11-27. Retrieved 2018-08-28.
  11. ^ 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.
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  13. ^ "Glossary". Cleveland, OH, USA: Compressed Air and Gas Institute. 2002. Archived from the original on 2007-09-02.
  14. ^ أ ب "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.{{cite web}}: CS1 maint: url-status (link)
  15. ^ Air Intake Filters (ISO 5011:2002). Geneva, Switzerland: International Organization for Standardization. 2002.
  16. ^ "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.
  17. ^ "Rule 102, Definition of Terms (Standard Conditions)", Amended December 2004, South Coast Air Quality Management District, Los Angeles, California, USA  SCAQMD Rule 102[dead link]
  18. ^ "49 C.F.R. § 171". Retrieved 22 May 2018.
  19. ^ Sierra Bullets. "Chapter 3 – Effects of Altitude and Atmospheric Conditions (Exterior Ballistics Section)". Rifle and Handgun Reloading Manual (5 ed.). Sedalia, MO, USA.
  20. ^ Gas turbines – Acceptance tests (ISO 2314:1989) (2 ed.). Geneva, Switzerland: International Organization for Standardization. 1989.
  21. ^ Gas turbines – Procurement – Part 2: Standard reference conditions and ratings (ISO 3977-2:1997). Geneva, Switzerland: International Organization for Standardization. 1997.
  22. ^ 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.
  23. ^ Association, Compressed Gas (2012-12-06). Compressed Gas Handbook. ISBN 9781461306733. Retrieved 22 Nov 2017.
  24. ^ "Chapter 3, Principles of Flight" (PDF). Pilot's Handbook of Aeronautical Knowledge. Federal Aviation Administration.[dead link]
  25. ^ Air Conditioners, liquid chilling packages and heat pumps with electrically driven compressors for space heating and cooling. UK: BSI EN. 2013.
  26. ^ Standard Atmosphere. Geneva, Switzerland: International Organization for Standardization. 1975.
  27. ^ Natural gas - Standard reference conditions. Geneva, Switzerland: International Organization for Standardization. 1996.
  28. ^ Gas analysis - Vocabulary. Geneva, Switzerland: International Organization for Standardization. 2015.
  29. ^ Referenzzustand, Normzustand, Normvolumen; Begriffe und Werte. 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
  • ويكيبيديا الإنجليزية
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