BS 2520:1983

Foreword
Committees responsible
Section one. General and barometric conventions
1. Scope
2. Pressure units
3. Conditions of mercury barometers
3.1 Standard conditions for general-purpose mercury
       barometers
3.2 Non-standard conditions for special-purpose
       mercury barometers
4. Application of conventions
Section two. Barometer tables
5. Categories of barometer covered
5.1 General
5.2 Fortin category
5.3 Kew category
6. Purpose and basis of tables
6.1 General
6.2 Interconversion of barometer pressure units
6.3 Correction of barometer readings to standard
       conditions
6.3.1 General
6.3.2 Correction to 0 deg C
6.3.3 Correction to standard gravity of 9.806 65 m/s(2)
6.4 Conversion of pressure reading from barometer
       level to another level
Appendices
A. Examples of the correction of barometer readings
A.1 Barometer measuring ambient pressure
A.2 Barometer measuring artificial pressure
A.3 Use of the tables to obtain the readings of
       a mercury barometer used in an airtight system
       at an ICAO pressure corresponding to a given
       altitude
B. History and advantages of the conventions
C. Testing of barometers
D. Information regarding the conventions
D.1 Relationships connecting the pressure units
D.2 Relationships connecting scales
D.3 Change from pre-1954 conventions to present
       standard conventions
Tables
Interconversion of barometric pressure units
1. Kilopascals and hectopascals (millibars) to
     millimetres of mercury and inches of mercury
2. Millimetres of mercury to kilopascals, hectopascals
     (millibars) and inches of mercury
3. Inches of mercury to kilopascals, hectopascals
     (millibars) and millimetres of mercury
Correction of barometer readings to standard temperature
(0 deg C)
4. Hectopascal (millibar) and millimetre-of-mercury
     Fortin barometers. Long-range table
5. Hectopascal (millibar) and millimetre-of-mercury
     Fortin barometers. Short-range table
6. Inch-of-mercury Fortin barometers. Long-range table
7. Inch-of-mercury Fortin barometers. Short-range table
8. Hectopascal (millibar) Kew barometers (MO pattern)
9. Millimetre-of-mercury Kew barometers (MO pattern)
10. Inch-of-mercury Kew barometers (MO pattern
11. Kew barometers for which V/A = 100 mm: correction
     additional to the Fortin correction
Correction of barometer readings to standard gravity
(9.806 65 m/s(2)) for latitude variation
12. All hectopascal (millibar) and millimetre-of-mercury
     barometers. Long-range table
13. All hectopascal (millibar) and millimetre-of-mercury
     barometers. Short-range table
14. All inch-of-mercury barometers. Long-range table
15. All inch-of-mercury barometers. Short-range table
Correction of mercury barometer readings to standard
gravity (9.806 65 m/s(2)) for altitude variation
16. Correction for height, in metres, above mean sea
     level
17. Correction for height, in feet, above mean sea level
Conversion of pressure reading from barometer level to
another level
18. All mercury barometers. Pressure difference per
     metre and per foot of vertical distance between
     barometer cistern and level in same building at
     which the pressure is required
Pressure units
19. Conversion factors for pressure units
20. Difference in scale reading caused by change from
     obsolete to present conventions

Specifies the conventions used for expressing barometric pressure, gives the standard conditions for all types of mercury barometer and provides comprehensive correction for routine aviation and meteorological applications with explanatory notes.