required for a specific heating requirement. The
types principally in use are natural gas, manufactured
gas, and liquid petroleum gas (table G, appendix II).
Natural gas is a mixture of combustible gases and
usually small amounts of inert gases obtained from
geologic formations. While the composition of natural
gas varies with the source, methane (CH4) is always
the major constituent. Most natural gases also contain
some ethane (C2H6) along with small amounts of
nitrogen and carbon dioxide (CO2). Natural gas is
colorless and odorless in its natural form; however; a
distinctive odor is usually added as a safety factor for
detecting leaks. Natural gas mixes readily and
completely with combustion air and thus is
substantially free from ash and practically smokeless.
T h e s e c h a r a c t e r i s t i c s c o n t r i b u t e t o g o o d
environmental pollution control. From a standpoint of
trouble-free performance, ease of handling, and
control, natural gas offers many advantages that make
it the most desirable of all heating fuels.
The common manufactured gases are carbureted
water gas, oil gas, and producer gas. These gases are
roughly one-half hydrogen and one-third methane,
plus small amounts of carbon dioxide, nitrogen, and
They are made by converting low-grade
liquid or solid fuels to the gaseous form by destructive
distillation (cracking) of oil or coal, by the
steam-carbon reaction, or by a combination of both
processes. These gases are ordinarily used at or near
the production point because of high manufacturing
costs rule out the added expense of distribution.
Liquefied Petroleum Gas
Liquefied petroleum gases are hydrocarbon gases
normally obtained as a by-product of oil refineries or
by stripping natural gas. These compounds are
normally gaseous under atmospheric conditions;
however, they can be liquefied by moderate pressure at
The principal LPG products are propane (C3H8)
and butane (C4H10). Propane, the most common, is
available by the bottle or cylinder and in bulk form. Its
boiling point is -44°F (note that this is very close to that
of refrigerant R-22).
Butane is generally available in bulk form. It boils
or vaporizes at 32°F. In other words, if the temperature
of butane is 32°F or lower, at atmospheric pressure, it
remains a liquid, and heat must be applied to bring it to
the gaseous state. Note in table G, appendix II, the high
heating. values of propane and butane.
Fuel oils are derived from crude oil, which consists
primarily of compounds of hydrogen and carbon
(hydrocarbons), and smaller amounts of oxygen,
nitrogen, and depending on the source, sulfur.
Practically all fuel oil is either a product or a
by-product of refining crude oil by the fractional
distillation process or by cracking.
The Bureau of Standards, United States
Department of Commerce, standardizes commercially
used fuel oils. The oils are numbered in grades 1, 2, 4,
5, and 6 and are titled commercial standard grades
(CSG). These grades are identified in the Navy by
military specifications and are intended for use in
oil-burning equipment for the generation of heat in
furnaces for heating buildings, for the generation of
steam, and for other purposes. A more in-depth
discussion of fuels and their characteristics is
contained in Fundamentals of Petroleum,
NAVEDTRA 10883. A comparison of fuel oils by
grade is given in table H, appendix II.
What are the principal types of gases used in
Fuel oils consist primarily of what compounds?
WARM-AIR HEATING EQUIPMENT
Learning Objective: Identify the different types of
warm-air heating units and equipment and basic
installation and maintenance guidelines.
Advances in the field of warm-air heating have
made it one of the most popular and widespread forms
of heating in use today. It has the advantage of
adaptability with various fuels and can be used in a
variety of buildings, including barracks, hangars,
personnel housing, schools, and theaters. It is likely,
therefore, that at one time or another you will be
responsible for performing technical maintenance and
repair and installation of warm-air heating equipment
The different types of heating equipment that will
be discussed include unit heaters, electric and gas- and