Section II. PUBLIC HEALTH ASPECTS OF ICE PLANTS
THE MANUFACTURE OF ICE
a. Many of the health hazards associated with ice relate to the manufacturing
process. As an inspector, you must be acquainted with the basic process and
equipment used to make ice.
b. Ice is made in the following manner:
(1) Water is placed into large cans (approximately 1' X 1.5' X 4.25')
called ice cans or freezing can. The cans are then immersed in tanks of brine.
Either sodium chloride or calcium chloride may be used in the brine tanks.
(2) A refrigerant maintains the temperature of the brine below the
freezing point of fresh water (6 F to 18 F). The refrigerant is a gas that is
compressed, cooled, and then allowed to expand in pipes that contact the brine.
Most commercial plants use ammonia as the refrigerant. Other refrigerants include
carbon dioxide, butane, sulphur dioxide, and ethyl chloride. The choice of refrigerant
depends on several factors: danger to life, corrosive action to metals, and the
pressure required to condense the gas into a liquid.
(3) The ice cans are able to hold 300 to 400 pounds (36 to 48 gallons) of
water. Usually a can filling tank is used to fill several ice cans at the same time. The
filled ice cans are lifted by cranes and positioned in the brine tank. A thin copper
pipe is placed in the center of each ice can and filtered air is bubbled through the
pipe. The pipe is commonly referred to as the "air bubbler." It is important that the
air bubbler not be contaminated. This is why filtered air is used. Because of the
bubbling air, freezing begins at the sides of the ice can and continues toward the
center. As the water freezes, impurities (including minerals) move to the center of
(4) Before the center (core) freezes, the core water is removed and
replaced with potable water. A pipe connected to a vacuum system is used for this
purpose. This pipe is known as the "core sucker." Again, it is critical that the core
sucker not become contaminated through contact with contaminated surfaces. The
original core name is removed before it freezes to increase the clarity of the ice and
to remove any unpleasant odors and tastes. The new core water is allowed to
(5) After 40 to 50 hours (approximately 1 hr/gallon of water), the ice cans
are removed from the brine tank and placed in another tank, called a dip tank, to
defrost the ice from the can. The ice is then put on a slide leading to the ice storage
The process is repeated to produce more ice.