Dispensing control system

The smallest cooling systems may simply be treated with filming amines in the form of slowly dissolving waxy blocks that are suspended in baskets, whereas larger or more difficult systems employ feed and control systems to dispense liquid products containing diamine acetates in an alcohol-water solvent system. 

Computer-controlled systems [54] are commonly used in clinical trials to control dispensing and manage site inventories of trial supplies. Such systems are implemented with telephone voice-based or Internet web-based systems. 

Therefore, the dispenser control panel should be equipped with a timer-relay device to insure that all admixture has been discharged from the conveying hoses or pipes. If the admixture dispenser system is operated manually, the plant operator should be furnished a valve with a detente discharge side to prolong the discharge cycle until it is ascertained that all admixture is in the concrete batch. 

Most dispensing systems are custom-made to meet the method of control or degree of automation required for the particular operation. Prior to installation of the dispenser, the system should be analyzed carefully to determine what possible batching errors could occur and, with the help of the admixture supplier, they should be eliminated. Commonly available dispensing systems and controls can be discussed under three main groups - fully automated, semi-automated or manual systems. 

The control systems for CNG refueling systems have evolved from being only mechanically controlled to some that are completely computer controlled today. Computer control offers flexibility not possible with mechanical systems and the ability to change the control strategy of the refueling system. Computer-controlled systems can also provide functions such as accounting of the amount of fuel dispensed into vehicles and billing functions. It is also possible to incorporate safety shut-down of the system if certain conditions are present. 

Propane refueling systems do not need elaborate control systems. The dispenser controls operation of the transfer pump, and emergency shut-down switches should be mounted near the dispenser and at some location between 6.1 m (20 ft) and 30.5 m (100 ft) from the dispenser. 

No control system beyond a start-stop switch on the dispenser for the transfer pump is needed. An emergency shut-down switch should be installed at a location remote from the dispenser that will shut down all the electricity to the dispensing station. 

Hydrogen dispensers will likely make use of programmable logic controllers or PC-based control systems. Both liquid hydrogen and compressed hydrogen dispensers will need to be able to monitor pressures and temperatures, open and close valves, turn on pumps, and interface with fire and emergency shut-down systems. 

Figure 3 is a schematic diagram of the pilot-test flow control system. The flow in the pilot-test tank was stratified into upper and lower zones created by the five upper injection/extraction wells and the five lower injection/extraction wells. The feed water was dispensed through a flow totalizer into the injection wells via a manifold and a series of ten controllable flow meters. The lower injection wells were fed directly with Beaverton city water. The upper injection wells were fed from three 6800-L tanks. Using three tanks allowed one tank to be actively supplying feed water, one to be full with the appropriate input solution, and one to be... 

In the production laboratory all synthesis and purification processes are carried out in remote-operated fully automated computer-controlled systems (synthesis modules, see Figure 7) located in heavily shielded hot cells (see Figure 8). Dispensing of individual doses is in many cases also carried out by automated systems. 

Palletizers can be furnished with automatic pallet dispensers, glue systems, automatic bottom-pad dispensers, and automatic tier-sheet dispensers. Palletizers offered are required to have a programmable logic controller (PLC) for multisize cases. It is possible to program different tier and pallet patterns into a PLC unit, and thus change over from one size to the other by means of selector switches. A palletizer can automatically arrange the cases for each tier, dispense the pallet, or insert the tier or tie sheets. These functions can alternatively be performed manually by an operator. 

Twenty-one dispensing programs can be stored in memory and retrieved. This type of liquid dispensing device can also be obtained as a computer-controlled system. 

In gas dynamic atomization, a liquid stream is broken-up into small entities which are dried very quickly. Because the formation of droplets occurs in aerodynamic suspension, the material experiences no shear and the liquid temperature does not rise above the local dew point, despite high gas temperatures. Since drying and subsequent cooling are rapid, organic materials do not have time to oxidize, degrade, or experience any other damage. Food powders often exhibit better flavor, texture, and instant characteristics than comparable powders from other spray dryers. Because a low pressure stream of slurry is pumped and dispensed, the system can also handle corrosive and abrasive products easily. Control over particle size is normally better. Fig. 7.82 depicts SEM photographs of some typical products. 

Network controllers Weighing/dispensing systems Batch control systems... 

Depending on the particular product, process and plant, the OCS will need to communicate to an extremely wide variety of devices. Experience in the 1990s suggests that these will include traditional PLC systems, intelligent instrumentation and other control systems (e.g., barcode readers, barcode printers, weigh and dispense systems, etc.). 

With the increasing trend to reduce even further the number of operators, some pharmaceutical companies are dispensing with the "traditional" control room (traditional in the sense of standard practice in the 1960s through to the present day). In many plants, operations are moving back out to the shop floor. This eliminates the need for two sets of operators (one in the control room and one in the production area), and often means a completely new method of operating the plant and interfacing with the control system. 

The principal structural features are as follows ceiling and walls are 1/4" thick methacrylate plastic floor and structural elements were aluminum. Approximate dimensions are 1 x 2 x 3 M. A heat exchanger supplied by external chilled water provided temperature and humidity control. Sensors buried in the vermiciiite or sand support medium allowed monitoring of soil moisture content. Carbon dioxide was provided from external cylinders, and nutrient was supplied to each plant through a sealed bulkhead. Alternatively, solid inorganic nutrient was provided from a pellet buried in the sand/vermiculite soil medium, and the condensed water of transpiration recycled and distributed to each plant by means of an automatic dispenser controlled by a preset timer. This system was probably most satisfactory from the viewpoint of eliminating periodic additions of external liquid nutrient and subsequent withdrawal of the condensed water of transpiration. 

The decision whether to correct deviations to a target value, or an absolute average value, is application related. In cases where the overall output has to coincide with a total amount dispensed, or when subsequent flow stream attenuation will smooth minor irregularities, then correction of any shortfall or overfeed is included in feed rate adjustments. For applications where the historical feed rate has immutable consequences, then any corrections should only seek to recover from the offset to the target feed rate and not compensate for past deviations. There is no benefit in compensatory over- or underfeeding when it is not possible to rectify a prior deviation. It cannot be too strongly emphasized that flow reliability is paramount. No control system, however sophisticated, can compensate for an inconsistent feeder performance. 

Packaged units have traditionally had their own progranunable logic controllers (PLCs) and local control panels. This is especially true in the case of units that require extensive sequence controls for stepwise processes such as filtration and ion exchange. Many operators find it more convenient to have control supervised from a central station. From this point of view, these systems are better controlled by a distributed control system (DCS) and monitored from the control room. Some who bought systems equipped with PLCs some years ago have dispensed with the PLCs and moved control to the DCS. Many favor systems which combine local control by PLC with status and alarm signals sent to the DCS. 

The moderate power density of the core allowed the designers to reduce the content of boric acid in the coolant compared to WER, to dispense with operational control of boric acid concentration at start up and shut down and for power manoeuvres. Slow compensation of reactivity for fuel bumup is provided by ion-exchange filters operating in the leak-tight closed purification and reactivity control system. 

Probably, one of the biggest nonevents (thankfully) was the year 2000 (Y2K) software scare that resulted in nothing. For those who may not remember, it was the fear that once we entered the Y2K, our industrial control systems would fail. The concern was that those industrial systems controlled by software or microprocessors that used formal dates as part of their operations would fail due to the hardware industrial system failing from the year changeover in 2000. Think about the industrial systems that we are dependent on electricity (not just to give us power but also to power our computer and software systems), clean water and water distribution, healthcare, ATM (cash dispense machines), air traffic control, pumping gas into your car, and millions of other everyday examples. Y2K did create a lot of fear and expense, which demonstrated how little we understood of our own industrial control systems. It also emphasized the importance of software safety and that software systems are used to control industrial systems, and we need to look at both to be sure that the industrial system operates safely. Today, the significant uptick in cyber attacks on industrial control systems further makes the point. 

In the majority of centrifugally controlled systems, the liquid handling proceeds in a pseudo-hydrostatic fashion governed by statically defined overflow, siphon and capillary principles. Highly dynamic break-up phenomena which are common, for instance, in contact-free liquid dispensers, are also possible, but rarely used. This means that the liquid handling performance can be made widely independent of the flow properties, in particular the viscosity of the processed liquid. Within the chambers, centrifugally induced buoyancy efficiently supports the removal of gas bubbles from the liquid bulk. 

This company s new pneumatic servo dispensing (PSD) system Is a positive rod displacement metering system that reportedly combines the cost efficiency of a pneumatic drive motor with the controlling accuracy of a servo drive motor. The PSD system uses a positive rod displacement metering principle for maximum dispensing... 

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