During the 1957-58 season, Palmer (59) found that a caustic soda solu- 
tion was not required to maintain a 5 percent CO, level in his CA rooms. The 
water circulated through the brine-spray unit in a CA room was being aerated in 
the work space outside the room, and there was enough gas exchange of CO, into 
the brine while it was in the CA room and out of the brine in the outside air 
to maintain the desired CO) level. Subsequent to Palmer's observations, de- 
tailed tests were performed to evaluate the usefulness of water as an absornent 
of C09. Smock and Yatsu (90), concentrating their study on methods of aeration, 
reported the most efficient system involved the use of a packed tower with 
counter-current airflow. In 1960, Pflug (70) presented a procedure for calcu- 
lating the rate of 0) reduction in a CA room and used it to compare the reduc- 
tion rate when caustic soda and water CO, absorbers were employed on rooms of 
several degrees of fullness and leakage rates, He found that only 2 to 3 days 
of additional time was required for a tight CA room to develop a 3 percent 05 
level with a water absorber in place of a caustic soda absorber. In later work, 
Pflug (71) describes the design and operating characteristics of a single tower 
water absorption-desorption system for removing CO, from a CA storage. Uota 
(98) in 1961 described a laboratory scale water scrubbing system for controlling 
COj levels in CA chambers. By regulating the flow rate of water through the 
exchanger, a relatively close control of the CO, levels was possible. 
Costs 
Loudon and Zuroske (47) reported in 1953 that the cost of storing 
Washington Red Delicious apples in a CA storage would be from 45 to 50 cents 
per box per season, or approximately 20 cents more per box than for ordinary 
cold storage. This estimate was based on conversion of existing cold storage 
facilities to a CA storage. Dalrymple (17) estimated in 1956 the cost of 
building a CA storage of 12,000-bushel capacity to be $2.75 per bushel, or 50 
cents more per bushel than a regular cold storage, and the cost of converting 
an existing cold storage of 12,000-bushel capacity to a CA storage to be 50 
cents per bushel, He also estimated the cost of storage in CA to be about 50 
cents per bushel per season, which he estimates is about double the cost of 
refrigerated storage, Dewey (19) reported the estimated cost of CA storage to 
be 50 cents per 40 pounds of fruit. Southwick and Zahradnik (92) estimated the 
cost of converting a regular cold storage to CA to be $0.80 to $1.50 per box and 
that of a new structure to range from $2.25 to $3.50 per box. In an attempt to 
reduce the costs of constructing a new CA storage, Zahradnik and Southwick (105) - 
found that a 7,000-bushel capacity CA storage could be built of plywood at a 
cost of $2.20 per box. By using their own workers to help in the construction, 
Greimer (30) and Johnson (41) reported costs of $1.75 and $1.76 per bushel for 
building their own CA storages. 
Regulations 
Several States have adopted regulations governing the operation of CA 
storages. New York was the first to do so. California (4), Michigan (5, 6), 
and Washington (7) also have such laws. They are similar to the New York law 
(3) which requires, in part, the annual registration of the rooms by the owner 
or operator of such rooms, that the room atmosphere meet a minimum 0, concen- 
tration of 5 percent within 20 days of sealing (30 days in Michigan), and that 
the fruit to be called CA fruit must be held in an atmosphere with not more than 
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