Other Factors Affecting CA Storages 
Operation and Maintenance of CA Rooms 
A number of publications are available that provide practical instruc- 
tions for the operation and maintenance of CA storages: Smock (86, 88), 
Phillips and Poapst (72, 77), Van Doren (100), Huelin and Tindale (38), Kidd 
and West (43), Southwick and Zahradnik (92), Pflug and Dewey (69). These pub- 
lications also discuss in varying degrees the design and construction details 
of a CA storage room, This includes methods of making a room gastight, the 
need for an outer vapor seal to prevent water from condensing in the insulation, 
and methods of testing a room for gastightness, as well as such special equip- 
ment, needed to operate a CA storage, as co. absorbers and gas analyses appara- 
tus. 
Attempts have been made to develop methods and utilize materials that 
are less costly than the masonry and metal storage structures in general use, 
but that would adequately meet the requirements of a CA storage. Pflug, Brandt, 
and Dewey (68) had an 800-bushel CA storage built of precast concrete wall 
slabs. The room served as a satisfactory CA storage but gusty winds at times 
caused an increase in the oxygen level of the storage atmosphere of 0.2 to 0.3 
percent in a 24-hour period. In a 1958 bulletin, Zahradnik and Southwick (105) 
detailed the design, construction, and performance characteristics, and the 
costs of an all-plywood CA storage. Their results indicate that this type of 
construction would serve adequately as a CA apple storage room, Layer (45), in 
a 1962 article, briefly discusses current construction of CA storages, 
Related research has been concerned with factors that affect the main- 
tenance of the room atmosphere. Pflug and Southwick (62) developed a method 
for measuring the leakage rate of a CA room and devised a way of reducing it by 
the use of a vinyl plastic breather bag. The breather bag reduces air leakage 
due to temperature cycling but does not reduce leakage from a pressure differ- 
ential induced by evaporator fans, wind, or changing barometric pressures (63, 
64). Pflug and Dewey in 1956 (65) presented an equation relating air leakage, 
respiration rate, room fullness, and oxygen equilibrium level for a CA storage. 
Zahradnik, Southwick, and Fore (104) found that improperly designed circulation 
within a CA storage with accompanying high atmosphere velocity may cause differ- 
ential pressures within the room, which in turn may result in an increased 
leakage rate, 
CO4 Scrubbers 
A number of different methods have been SA to remove the carbon 
dioxide from CA storages. The atmospheric washer, absorber or scrubber, as 
it is variously called, originally used calcium or etic hydroxide in ESIUeHOn 
as the CO» absorbing agent (43). In 1957, Pflug, Angelini, and Dewey (66) re- 
viewed the fundamentals of CO, absorption in discussing three of the most com- 
monly used absorbers; the barrel-type designed by Smock and Van Doren, the 
brine-spray type of Kedenburg (42), and the packed-tower of Pflug, et al. (67). 
Eaves (23) developed a dry scrubber that uses dry hydrated lime. Simply by 
passing the CA atmosphere over these bags, he was able to maintain the CO, level 
as low as 0.8 percent. A solution of mono-ethanolamine has been used by Mann 
(49) to absorb CO). This solution can be regenerated by heating and reused, 
thus eliminating the need for recharging the absorber. 
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