FED-STD-228A
METE
SAMPLING
HYGROMETE
MANOMETE
ASPIRATO
SECOND
TEST CHAMBER
DRIE
SUPPL
WATER
FIGURE 4111.
3.1.1.1 An air pump or compressed air supply for circulating air through the test chamber.
3.1.1.2 An air drier consisting of 500 ml gas washing bottles filled to about 30 percent of capacity with
sulfuric acid, sp. Gr. 1.83, connected in series with a drier containing anhydrous calcium chloride or other
suitable desiccant.
3.1.1.3 A moisture indicator consisting of a U-tube hygrometer containing anhydrous copper sulfate.
3.1.1.4 A calibrated flow meter having a capacity of at least 25 cu. Ft. per hour, for measuring the rate of
flow of air through the system.
3.1.1.5 A generator for ozonizing the air consists of two concentric electrodes, separated by a thin glass
dielectric, between which voltage is applied. The generator is supplied by a potential transformer
equipped with variable voltage control of 20 to 30 kilovolt rating.
3.1.1.6 An aging chamber of ozone-resisting material and of sufficient size to accommodate the largest
specimen to be tested. A chamber of about 18 to 20 inches in height with a capacity of from 2,000 to
5,000 cubic inches is usually required. A convenient form of chamber is a glass jar with cover which
permits easy access to the interior and allows inspection of the specimen without opening the chamber.
The chamber is equipped with a mineral wool filter placed between two perforated grills near the bottom.
The ozonized air is lead from the generator to a space below the filter. If an air conditioned room is not
available, the temperature of the chamber may be controlled by immersing it in a water bath with
accurately controlled temperature. A thermometer is placed in the chamber with the bulb as near the
specimen as possible. The chamber is equipped with a two-way stopcock, one acting as a discharge to
the outside and the other as a bypass.
3.1.1.7 A manometer for measuring the pressure is connected to the outlet pipe of the aging chamber.
3.1.1.8 A sampling bottle for collecting a specimen for the determination of ozone concentration is
connected to the outlet tube of the chamber.
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