Stop-drop programs

A more easily defined situation can be seen in production of Macintosh apples. These apples, which make up a very significant portion of the northeastern U.S. apple crop, are notorious for dropping off the tree as soon as they have reached maturity. Prior to the development of stop-drop chemicals, it was expected that at least 20-25% of the crop would go on the ground before harvest. The stop-drop programs of today can virtually eliminate this problem, spread the harvest over a longer period of time, and improve the quality of the fruit as it is sold fresh or as it comes out of long-term storages. The value of the stop-drop effect alone could be calculated to be at least 500 on a 300-box-per-acre yield. 

The influence of inhibitor on the performance of a semi-continuous reactor can be, in some ways, similar to both batch and continuous systems. A dead time is usually observed upon addition of the initial charge. When the secondary stream flow is started after some reaction of the initial charge, additional inhibitor flows into the reactor and the initiation rate drops. When this programmed addition is stopped the initiation rate increases sometimes enough to cause temperature control problems. 

Acid leaks result in the deactivation of some chemical treatment programs, for example, P-PO4 is hydrolyzed to O-PO4, and chromate (in the presence of ferrous ions) is reduced to trivalent chromium. Also, depassivation of the inhibitor film and corrosion occurs. The correct action is to first stop the leak, then to increase the pH by bleeding off the low pH water and making up, to the maximum extent of the system. If the leak is so severe that the pH drops below 4.3, and free mineral acidity (FMA) occurs, soda ash should be used to restore the pH to 4.3 to 4.5, then discontinued. Caustic soda should not be added, as this action will almost certainly result in heavy fouling from precipitated ferric hydroxide. Dispersants or antifoulants may be required. When the system is stabilized, it should be repassivated and the reason for the acid leak resolved (faulty pH meter ). 

The interface (Fig. 1) was designed for easy and minimal interaction. Each user must train the voice recognition engine to be able to work accurately with the program. The user selection is done from a drop-down menu. Voice commands are used to start and end a run. The preparation and start of the run consist of two voice commands Ready, then Inject at the injeetion of the sample. The Stop command ends the run. During the run, all of the user s comments are added in a text box along with the retention time. These comments can be edited at the end of the run. 

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