UFC 3-240-13FN
25 May 2005
contaminant on the equipment. Installing a dealkalizer to process the makeup water and
thereby reduce the levels of bicarbonate and carbonate alkalinity is an alternative to
using neutralizing amines. Using a dealkalizer effectively reduces, and may even
eliminate, the need for neutralizing amines to reduce carbon dioxide corrosion. Steam-
to-steam heat exchangers may be used to raise sterile steam.
3-2.7.6.2
Food Preparation. The use of neutralizing amines or filming amines is
prohibited if the steam contacts milk or milk products. In addition, to provide a margin of
safety, the military prohibits any amines in steam used directly for cooking. This may be
a sufficient reason to prevent using building steam in food preparation kitchens. In some
cases, kitchens use steam to heat jacketed kettles in which food is heated. This
application of steam as a heat source does not involve direct contact of the steam with
foodstuffs. In other cases, direct contact between the steam and the foodstuffs is the
method used to provide heating. There may be concerns that the amines will impart an
amine taste or odor to the food. To alleviate this concern, use package steam
generators to provide a source of steam that is independent of the building steam
system. Another alternative is to use a steam-to-steam heat exchanger.
3-2.7.6.3
Humidification. Steam is often used to humidify the air in buildings. The
use of amines may raise a concern of contamination of the air in the building. To
provide a margin of safety, the military prohibits using amines in steam that is used
directly for humidification. Normally, the quantity of an amine in the air of a steam-
humidified building is quite small, usually in the low ppb range; however, packaged
steam generators can eliminate this concern.
3-2.8
Water Carryover in Steam. The steam that is produced from boiler water
should not contain any liquid water. Common causes of water droplets or impurities
being carried into the steam are misting, foaming, priming, and silica carryover.
3-2.8.1.
Mist Carryover. The term "misting" refers to a process in which a fine mist
is produced as water boils. This 3-stage process is illustrated in Figure 3-14. In stage 1,
a bubble of steam vapor reaches the water surface. In stage 2, the bubble bursts,
leaving a dent in the water. In stage 3, the water rises to fill the dent. The center of the
dent fills at a faster rate than the edges resulting in a small droplet of boiler water that is
thrown off as a fine mist. Most, if not all, of the mist is removed in the mist eliminator
section of the steam drum; however, any mist that is not removed will be entrained in
the steam. These fine droplets will have the same level of dissolved solids as the boiler
water and will contaminate the steam and the condensate.
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