Propane. Propane should be the fuel for the 19F and
21C12 series trainers. It has a standard and reliable chemical
composition as opposed to natural gas which is a blend of
chemicals. Propane gives the desirable flame characteristics
and has been tested for environmental acceptability in the
training situation. Complete stoichiometric burning of propane
requires 23 cubic meters (cu. m) of air for each cubic meter of
fuel at atmospheric pressure. The following criteria is
provided pertaining to propane as outlined in NFPA 58, Storage
and Handling of Liquefied Petroleum Gases:
a) Properties and characteristics of liquefied
petroleum (LP) gases. Propane has certain properties and
characteristics which must be understood by the persons handling
and processing these products.
(1) They are normally gases but are changed to
liquid state by the application of moderate pressure. At
atmospheric pressure commercial propane boils at minus 42.2
degrees C. It is evident that at normal atmospheric
temperatures and pressures, propane will be in a gaseous form.
Propane in liquid state and open to the atmosphere will
evaporate (not boil) although the atmospheric temperature may be
(2) LP gases contain no toxic components such as
carbon monoxide. However, the vapors should not be inhaled as
serious accidents could occur from ignition of gases contained
in the lungs.
(3) LP gases are heavier than air. With air
equal to 1.0, the specific gravity of propane is 1.52. LP gas
will, therefore, collect in low places but will eventually
diffuse into the atmosphere.
(4) The explosive range of propane-air mixture is
lower and narrower than with other fuel gases and is 2.15 (lower
explosive limit) to 9.6 (higher explosive limit) percent in air.
The lower explosive limit is the limit at which combustion of
propane can be sustained. The higher explosive limit is the
limit at which the combustion of propane cannot be sustained.