The Horticultural Research Center contains five storage rooms, four of 

 which are normally operated as CA rooms; two rooms have a capacity of 2500 

 bushels each and the other two have a capacity of 600 bushels each. 

 Previously, temperature has been monitored by a single mercury thermometer 

 placed inside the door of each room, and any adjustment of temperatures has 

 been done manually. O2 and CO2 were measured daily with a single Orsat 

 analyzer, samples being drawn from each room with an electric pump. O2 was 

 added as needed by operating a controlled leak in the door, and CO2 was 

 scrubbed when necessary using a lime box. O2 pulldown was achieved with a 

 liquid-N2 system. 



The system established in 1986 was as follows. Temperature monitoring was 

 upgraded by installing multiple thermocouples in each room, following Cornell 

 University recommendations (Cornell University Agricultural Engineering 

 Extension Bulletin 430). A coimnercially available paramagnetic O2 analyzer and 

 a commercially available infrared CO2 analyzer were obtained to replace the 

 Orsat analyzer. These electronic measuring devices were supplied with air 

 drawn from a room by a new electric pump through the copper sampling lines that 

 previously supplied the air for the Orsat. The existing solenoid valves on 

 these lines were wired via a relay board to a conventional personal computer. 



A commercially available software package, designed for use in automatic 

 monitoring and controlling systems, was set up so that an air sample was drawn 

 hourly from each room and passed through the O2 and CO2 monitors. Analyses 

 were recorded on both a disc and on a print-out. Also, at each sampling time, 

 temperature at one thermocouple in each room was measured and recorded. Later 

 in the season a dewpoint indicator was purchased for humidity measurement, and 

 subsequently each sample was also measured for relative humidity and these data 

 were also recorded. Thus, an hourly record of O2, CO2, temperature, and 

 relative humidity within each room was automatically obtained. (The system 

 could have been programmed for either more frequent or less frequent sampling 

 or recording.) 



The system can be programmed so that adjustments of temperature, O2, and 

 CO2 can be made automatically when the measured values exceed previously 

 established limits. For example, a temperature of 37°F might be desired and 

 the program might change the temperature control setting if it falls below 

 36.5°F or rises above 37.5°F. In our first season we continued to control 

 temperature manually and to operate the lime box manually. However, O2 control 

 was automated. Each room possessed 4-inch PVC inlet and outlet lines fitted 

 with large solenoid valves. A cylinder of N2 gas and a squirrel cage fan were 

 attached to the inlet manifold. The system was programmed so that when an O2 

 reading fell below 2.5% or rose above 3.5%, the control system was activated 

 via the relay board. This system vented either air or N2 into the room, 

 depending on whether O2 was too low or too high. Outlet valves were also 

 opened automatically to relieve the positive pressure caused by air or N2 

 addition to a room. 



The system worked reasonably smoothly, given that this was its first year 

 of operation and we were developing it as time and availability of supplies 

 permitted. During the summer we shall complete some unfinished wiring and 

 plumbing, and we anticipate that we shall go into the 1987-88 season with a 

 completed system and with the operators now being familiar with the operation 

 and the equipment. The operators had little previous experience with computer 



