William V. Richards
The broad term refrigeration refers to a general science concerned with the use of
producing temperatures below normal for commercial or other useful purposes.
Refrigeration piping is used in conjunction with refrigeration equipment. Refriger-
ants are fluids which absorb heat by evaporating at a lower temperature and pressure
and transfer heat out when they condense at a higher pressure and temperature.
The increase in pressure necessary to elevate the temperature level is produced by
a compressor of the reciprocating, rotary, or centrifugal type. In the case of an
absorption system, the transfer of heat, thereby boiling the more volatile refrigerant
out of a solution.
Fluids which do not change state are sometimes used to transfer heat in an
indirect system. Such fluids are called secondary coolants. To be classified as a
secondary coolant, the fluid must be used for the transfer of heat without a change
in its state. Brine, a solution of salt and water, is a secondary coolant.
Many fluids have been used as volatile refrigerants in the evaporation, compres-
sion, condensing, and expansion cycle. This chapter will deal with application and
structural design of piping for the more commonly used volatile refrigerants such
as ammonia and some of the halogenated hydrocarbons. It will also cover general
methods for other refrigerants where specific tables are not presented. Since volatile
refrigerants are used in the liquid, vapor, and mixture phases, each of these will
be treated separately.
Many fluids have been used for brines. Originally, the term brines applied to
salt solutions such as calcium chloride or sodium chloride. The use of such salt
brines permitted the transfer of heat at lower temperature levels without introducing
refrigerant of the volatile type into refrigerated spaces. These brines were commonly
used for cold storage plants, ice plants, or commercial and process refrigeration.
Solutions of g