WHAT'S NEW WITH CA STORAGE 



William J. Bramlage 

 Department of Plant and Soil Sciences 



A National Controlled Atmosphere Research Conference was spon- 

 sored at Michigan State University by the M.S.U Department of Horti- 

 culture on January 27-28, 1969. This conference was attended by CA 

 research personnel from throughout the U.S. and from many other 

 countries, and the participants discussed current information and 

 thinking on all aspects of CA storage. The conference very success- 

 fully up-dated information on CA storage, and it was the author's 

 privilege to participate in it. A resume of the conference proceed- 

 ings is presented here. 



The conference was divided into 6 sessions, and one of these 

 sessions dealt with construction of CA storages. R.M. Smock (Corn- 

 ell) discussed methods tried in New York and pointed out many im- 

 portant observations. He noted that moisture accumulation in the 

 walls is a critical problem--as a result of it the wooden structures 

 of many rooms have rotted. He has never found moisture problems in 

 the ceiling of rooms with wel 1 -venti 1 ated attic spaces i\n which 

 case the exterior vapor seal should be omitted). He feels that 

 flat roofs on a CA storage present a moisture-accumulation hazard 

 and should be avoided. In the walls, wood should be kept to a min- 

 imum, he believes, and where used, it should be redwood or pressure- 

 treated timber. He has observed a number of rooms that have a ven- 

 tilated space running between the exterior wall and the insulation, 

 with the exterior vapor seal left off, and he has seen no moisture 

 problems in these walls. 



Dr. Smock noted that while rooms have been successfully built 

 with no gas seal in the floor, there have been enough failures that 

 it would be better to install floor gas seals. For wall gas seals, 

 he personally favors 28 gauge galvanized iron sheeting. However, 

 sprayed-on polyurethane is working very well, and he believes that 

 it is approaching a competitive level in cost and should be given 

 very serious consideration as a gas seal. 



J.W. Zahradnik (Massachusetts) discussed the use of polyvinyl- 

 chloride as an external gas seal, and pointed out that when proper- 

 ly applied it works excellently. He discussed an engineered con- 

 cept of CA construction that has been used and which has resulted 

 in a structure largely built by farm labor during the winter; this 

 storage cost $2.02 per box to construct in 1967, in contrast to a 

 comparable structure built for $2.20 per box in 1957. Dr. Zahrad- 

 nik also noted that he feels a floor seal is very important, and 

 that he favors the use of wood in the structural framework wherever 

 possible to reduce costs. 



H.C. Dostal (Purdue) presented a movie showing construction of 

 an experimental Styrof oam-dome CA storage at Purdue. This dome 

 took 5 men 12 hours to construct, and haS immense structural strength 



