Chapter 6 Introduction to Refrigerants
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6.3.3 Refrigerant Cylinder Color Code
Refrigerant cylinders are often color coded for easy
identification. This practice helps to prevent accidental
mixing of refrigerants within a system. A color code
is not a requirement for all manufacturers. In addi-
tion, there are several colors that appear similar, so it
is important to always read the label and identify the
refrigerant by its ASHRAE number before using a cyl-
inder. Popular refrigerants, with their R-numbers and
cylinder color codes, are listed in Figure 6-6. Cylinders
for recovered refrigerants are gray with yellow ends.
These cylinders must be rated and approved for use by
the Department of Transportation (DOT).
6.4 Refrigerant Properties
Refrigerants are designed for specific types of equip-
ment based on the amount of heat they are required to
transfer. There are refrigerants for low-temperature
applications (freezer), medium-temperature applications
(refrigeration), and comfort-cooling applications (air
conditioning).
There is a great deal of information about refrig-
erants that HVACR technicians need to know. Much
of this information is useful in understanding the
refrigeration cycle in different systems. It is impor-
tant to become familiar with pressure-enthalpy tables,
pressure-enthalpy diagrams, and refrigerant charac-
teristics and classification.
6.4.1 Refrigerant Toxicity
and Flammability Properties
Various organizations have cataloged refrigerants
based on levels of toxicity and flammability. Of par-
ticular importance to HVACR technicians, ASHRAE
Standard 34 groups refrigerants by toxicity and flam-
mability, Figure 6-7.
Toxicity is the ability of a refrigerant to be harm-
ful or lethal with acute or chronic exposure. This
exposure may be by contact, inhalation, or ingestion.
Class A refrigerants are those not known to be toxic at
concentrations equal to or below 400 parts per million
(ppm). Class B refrigerants are those that are known to
be toxic at concentrations equal to or below 400 ppm.
Flammability is a substance’s capacity to ignite
and burn. Certain refrigerants may form a flammable
mixture when blended with air. Refrigerant flam-
mability classification is indicated by the following
numbers: 1 (no flammability), 2 or 2L (low flammabil-
ity), or 3 (high flammability). The 2L designation for
low flammability indicates substances that meet the
requirements for low flammability (2) and, in addition,
Refrigerant Cylinder Color Code
Refrigerant
Number Cylinder Color Type
R-11 Orange CFC
R-12 White CFC
R-13 Light blue (sky) CFC
R-13B1 Pinkish-red (coral) CFC
R-22 Light green HCFC
R-23 Light blue-gray HFC
R-113 Dark purple (violet) CFC
R-114 Dark blue (navy) CFC
R-123 Light blue-gray HCFC
R-124 Deep green (DOT
green)
HCFC
R-125 Medium brown (tan) HFC
R-134a Light blue (sky) HFC
R-401A Pinkish-red (coral) HCFC
R-401B Yellow-brown
(mustard)
HCFC
R-401C Blue-green (aqua) HCFC
R-402A Light brown (sand) HCFC
R-402B Green-brown (olive) HCFC
R-404A Orange HFC
R-407A Lime green HFC
R-407B Cream HFC
R-407C Medium brown HFC
R-410A Rose HFC
R-500 Yellow CFC
R-502 Light purple (lavender) CFC
R-503 Blue-green (aqua) CFC
R-507A Blue-green (teal) HFC
R-717 Silver Inorganic
compound
Figure 6-6. Table listing some of the more commonly used
refrigerants and their corresponding color codes.
have a slow burn velocity. This means that substances
categorized as 2L are hard to ignite and form flames
that are easy to extinguish. Figure 6-8 shows the safety
classifications of some common refrigerants.