Company Writer's Guide

Symbols for Units in General Use
UnitSymbolNotes

 

 

 

ampere

A

SI unit of electric current.

 

 

 

ampere (turn)

A

SI unit of magnetomotive force.

 

 

 

ampere-hour

Ah

Also A•h

 

 

 

ampere per meter

A/m

SI unit of magnetic field strength.

 

 

 

angstrom

 

1 = 10-10m (deprecated, see ANSI Z210.1-1976)

 

 

 

atmosphere, standard

atm

1 atm = 101 325 Pa (deprecated, see ANSI Z210.1-

 

 

1976)

 

 

 

atmosphere, technical

at

1 at = 1 kgf/cm2 (deprecated,

 

 

see ANSI Z210.1-1976)

 

 

 

atomic mass unit (unified)

u

The (unified) atomic mass unit is defined as one

 

 

twelfth of the mass of an atom of the 12C nuclide.

 

 

Use of the old atomic mass (amu), defined by

 

 

reference to oxygen, is deprecated.

 

 

 

atto

a

SI prefix for 10-18.

 

 

 

attoampere

aA

 

 

 

 

bar

bar

1 bar = 100 kPa. Use of the bar is strongly

 

 

discouraged (see ANSI Z210.1-1976), except for

 

 

limited use in meteorology.

 

 

 

barn

b

1 b = 10-28m2

 

 

 

barrel

bbl

1 bbl = 42 galUS = 158.99 L

 

 

 

barrel per day

bbl/d

This is the standard barrel used for petroleum,

 

 

etc. A different standard barrel is used for fruits,

 

 

vegetables, and dry commodities.

 

 

 

baud

Bd

In telecommunications, a unit of signaling speed

 

 

equal to one element per second. The signaling

 

 

speed in bauds is equal to the reciprocal of the

 

 

signal element length in seconds.

 

 

 

[For Illustration Only]

B-4