Punctuation

Colons

As a Chemical Engineering student, you especially need to review use of the colon when introducing an equation, list, figure, table, etc. When introducing an equation or a list, do not put a colon after the words "when," "where," "if," "therefore," etc.

Example: PV = nRT

where

P = absolute pressure of the gas
V = volume of the gas
n = number of moles of the gas
R = gas constant
T = absolute temperature of the gas

Be sure that a complete sentence (an independent clause) precedes the colon, and avoid putting colons after dependent clauses ending with "is," "by," "are," "such as," "especially," "including," etc.

Example

The result was the following equation:

or

The result was

Example

The basic energy balance equation is as follows:

Accumulation = flow in - flow out

or

The basic energy balance equation is

Accumulation = flow in - flow out

Commas

For clarity, retain the comma before the coordinate conjunction in a series of three or more items.

Example

The static head, friction losses, velocity head, and minor losses must be added for the three points to be calculated.

Two independent clauses (two clauses that could stand alone as complete sentences) should not be joined with only a comma. Use a semicolon or a period to join these clauses.

Incorrect Never measure explosive gas concentrations with inappropriate equipment, use only equipment that OSHA and NFPA have recommended.
Revised Never measure explosive gas concentrations with inappropriate equipment; use only equipment that OSHA and NFPA have recommended.