Automatic instrument, definition

Before initiating an analysis, the instrument must be programmed for automatic operation and the samples placed in the appropriate positions of the injector. Dialog 16, shown in Figure 2, starts operation of the microcomputer. Intelink communication with the instrument is established and the parameters for the first sample are taken from the sample definition file on the minicomputer and are transmitted to the microcomputer. The microcomputer turns on a ready status light at the instrument to signal to the operator to begin automatic operation of the instrument. 

Few definitive thermal studies of metal-containing polymers (with the exception of silicon-containing polymers) exist in the literature. Thermal analysis is typically done as a matter of preliminary testing on new polymers. Further, most of the studies were done prior to the advent of the automatic, programmed thennal analysis instruments. 

For regular tests a LIMS offers the functionality of automatic test programs that are used for processes, which can be planned exactly. Examples are calibration of instruments, audits, and assessment of environmental impact in regular intervals. After an automatic test program has been initiated, it starts working on a predefined relative date or time to compile and generate processes on the basis of the respective definitions in the standard. 

This idea was embodied in the IUPAC definition of automatic systems "The use of combinations of mechanical and instrumental devices to replace, refine, extend, or supplement human effort and faculties in the performance of a given process, in which at least one major operation is controlled, without human intervention, by a feedback system"[367]. The key point for an automatic system is therefore the incorporation of a feedback system, i.e. the "combination of a sensing and a commanding device that can modify the performance of a given act" [367[. In other words, the response of a sensing device is used for the real-time modification of system operation. These definitions also hold for flow analysis automatic analysers are expert flow systems (Fig. 8.26), often referred to as smart or intelligent flow systems. 

The distinctions established by IUPAC are clear-cut. Thus, the speed of titrant addition is always constant in an automatic titrator, whereas it Is adjusted by a feedback system according to the nearnesa of the equivalence point in an automated titrator. However, some workers [11,12] acknowledge the accuracy of these definitions but consider them too stringent. Very often, the term automatic Is used to refer to systems with and without feedback Indistinctly. In any case, whenever the concept automatic process Is referred to In this book, It will be meant In its widest connotation, namely that Involving partial or complete elimination of human Intervention not related to Instrumentation. 

It is immediately apparent that the complete automation of this sub-stage is a difficult task. Only in a few instances (e.g. the automatic in vivo determinations described In Chapter 14 and performed with the on-line process analysers dealt with in Chapter 17) is this ideal objective affordable. Much more often, some of the above-mentioned operations involve human participation, although It is still termed automated [1]. Therefore, although many clinical analysers are classed as automatic, the blood and urine samples that they handle are collected and even treated manually before they are placed on the sampler. Such is also the case with automatic off-line water pollutant analysers, also calling for manual collection and preservation of samples. Consequently, the automated sampling concept as used here refers to the Introduction Into the analyser or instrument concerned of a definite portion of sample collected from its source and even treated manually, with the few exceptions stated above. 

The reason why some clinical methods should be labelled automatic or not Is not completely clear. The generic definition does not establish the extent to which human effort need be replaced or the method concerned be facilitated for the latter to deserve to be categorized as automatic . A manual method is rarely considered automatic merely because It calls for a water-bath whose temperature Is adjusted by means of a feed-back mechanism. On the other hand, self-contained continuous-flow instruments including the sampler, peristaltic pump, dialyser, spectrophotometer with flow-cell and recorder are common although, according to IUPAC s definition, Improperly called automated . In fact, few of the elements of such Instruments, apart from the dialyser bath or the recorder servo, are regulated by a feed-back mechanism. 

Many practitioners define "Fail-Danger" as a failure that prevents a safety instrumented function from performing its automatic protection function. Variations of this definition exist in standards. lEC 61508 provides a definition similar to the one used herein, which reads "failure which has the potential to put the safety-related system in a hazardous or fail-to-function state." The definition from lEC 61508 goes on to add a... 

The schematic representation of the self-designed experimental set-up applied for automatic and online measurement of dielectric properties of well conducting liquids in a definite temperature range is shown in Figure 1. It is composed of the following devices and instruments cylindrical sample holder unit, thermostat, peristaltic pump, waveguide, temperature sensor, displaceable piston, stepper motor, magnetron, detectors, control unit, and a PC. 

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