Abbreviations are often used to create a headline for the pipe marker that can be read from a long distance. Abbreviations, for example, are used in the International Institute of Ammonia Refrigeration (IIAR) Standards. Abbreviations can also be used to shorten a long legend. See example below:

Many find the lower wording rather cryptic. A better choice might be to use an abbreviation for only one of the words; for example, COND WATER RETURN or CONDENSER WTR RETURN.

For our recommended list of abbreviations, consult the ANSI Standard Y1.1-1989. Of course, abbreviations should be used only when their meaning is clear. When in doubt spell it out! It is often preferable to use a longer pipe marker or a different design, rather than force the legend into hard-to-read skinny letters.