-8- 



are less. There is no strain of Mcintosh that will produce 1001 

 red color like many Delicious strains. To obtain a high packout 

 of Extra Fancy Mcintosh fruit we need well pruned, well managed, 

 and non-crowded trees and long-term storage potential of fruit. 

 Many Massachusetts growers store , grade, and sell themselves at 

 least part of their crop which means less time is available for 

 the orchard. This generally is not true in the Pacific North- 

 west. Lastly and perhaps the most important reason for our 

 lower tree densities is Yankee conservatism. 



********** 



CONTROLLED ATMOSPHERE GENERATORS - THEIR FUNCTION AND MALFUNCTION 



David R. Dilley 

 Horticulture Department 

 Michigan State University* 



The process of controlled atmosphere (CA) storage consists of 

 storing fruit in a virtually air tight and well insulated refrig- 

 erated room at high humidity in 2 to 31 oxygen plus 1 to 51 carbon 

 dioxide with the balance of the atmosphere being mostly nitrogen. 

 Room size varies from 10,000 to 100,000 cubic feet. Various means 

 are employed to adjust the gas atmosphere initially and to sub- 

 sequently control it for storage duration of up to 10 months. 



The disastrous explosion of a controlled atmosphere storage 

 room and resulting personal tragedy at Peabody Orchards, Inc. near 

 Fenton, Michigan in November (See GLFGN Nov. 1981) caused great 

 concern among storage operators and suppliers. This accident 

 occurred as an Arcat CA generator was being employed to lower the 

 oxygen level for the CA storage of apples. Propane gas used in the 

 CA generator was theorized to have accumulated to an explosive con- 

 centration in the sealed room. Several kinds of CA generators are 

 used in Michigan and elsewhere that are fueled by natural gas or 

 propane. The purpose of this article is to describe CA generators 

 and to answer many questions that have risen since the storage dis- 

 aster. Hopefully, this will direct the attention and action of 

 owners, operators and suppliers of this equipment to ensure that 

 all possible precautions are taken to prevent such accidents in 

 the future. More knowledge about CA generators may also be import- 

 ant to arrest unwarranted fear in the use of this important equip- 

 ment and technology for fruit storage. 





* 



Printed with permission of the author. Article originally prepared 

 for the Great Lakes Fruit Growers News. 



