Software, computer control

Software by itself cannot be a hazard. What is a hazard is what the software control will enable to occur. Integrated control systems are ubiquitous in our plants. Software, computer control, and Internet-enabling and monitoring systems perform many of the following functions listed. Most of these items are controlled by software. So, when you look at hazards in the following list, you also need to look at the systems that control them to be complete in your analysis. 

The mechanical parts of computer-controlled viscometers can be simple and should not become obsolete for many years. The complexity is in the software, and this is where changes will have to be made to keep the instmment up to date. Some manufacturers are offering new, updated software free for a period of several years after the instmment is purchased. 

The team should have a wide range of knowledge and experience. If a contractor designs the plant, then the HAZOP team should include people from both tlie contractor and client organizations. On a computer-controlled batch plant, the software engineer should be a member of the HAZOP team, which should include at least one other person who understands the computer logic. 

Today it is usually harder than in the early days of computer control for operators to interfere with the software, override interlocks, or type in coiTect readings. However, many operators acquire keys or passw ords that they should not have, in much the same way as operators have always unofficially acquired and secreted an assortment of tools and adaptors. On one plant an interlock was found to be illegally blocked the password had been disclosed to 40 people, all of whom denied responsi-aility (see Section 14.5 d). 

Against high levels of computer control Is the pre-batch preparation time required for sequencing, software writing and parameter setting, the full details of the latter of course often not available. This activity Is acceptable as a precursor to full scale production but Is felt restrictive and could Inhibit flexibility In a pilot plant. 

A detailed description of hardware, software and mathematical analysis of the computer controlled batch reactor system is... 

Software to continuously update and optimise plant performance can be incorporated in the computer control systems. 

A computer-controlled rheology laboratory has been constructed to study and optimize fluids used in hydraulic fracturing applications. Instruments consist of both pressurized capillary viscometers and concentric cylinder rotational viscometers. Computer control, data acquisition and analysis are accomplished by two Hewlett Packard 1000 computers. Custom software provides menu-driven programs for Instrument control, data retrieval and data analysis. 

A computer controls the whole measurement process dedicated software allows to perform surface scanning, spectral averages and acquisition of the... 

The instrumentation for voltammetry is relatively simple. With the advent of analog operational amplifiers, personal computers, and inexpensive data acquisition-control system, many computer-controlled electrochemical systems are commercially available or custom made. Programming complex excitation waveforms and fast data acquisition have become a matter of software writing. 

The model 1020 software package includes interactive programmes specifically designed for complex mixture analysis and advanced automated programmes for routine analysis. All system functions are computer controlled with minimal knowledge of mass spectrometry. 

An even greater pitfall into which many young process control engineers fall, particularly in recent years, is to get so involved in the fancy computer control hardware that is now available that they lose sight of the process control objectives. All the beautifiil CRT displays and the blue smoke and mirrors that computer control salespersons are notorious for using to sell hardware and software can easily seduce the unsuspecting control engineer. Keep in mind your main objective to come up with an effective control system. How you implement it, in a sophisticated computer or in simple pneumatic instruments, is of much less importance. 

In addition to the basic control loops, all processes have instrumentation that (1) sounds alarms to alert the operator to any abnormal or unsafe condition, and (2) shuts down the process if unsafe conditions are detected or equipment fails. For example, if a compressor motor overloads and the electrical control system on the motor shuts down the motor, the rest of the process will usually have to be shut down immediately. This type of instrumentation is called an interlock. It either shuts a control valve completely or drives the control valve wide open. Other examples of conditions that can interlock a process down include failure of a feed or reflux pump, detection of high pressure or temperature in a vessel, and indication of high or low liquid level in a tank or column base. Interlocks are usually achieved by pressure, mechanical, or electrical switches. They can be included in the computer software in a computer control system, but they are usually hard-wired for reliability and redundancy. 

Note As is often the case, the HPLC system will be under computer control, which is likely to be part of a data-handling system. Since the data generated from the OQ hardware tests typically require chromatographic data handling, the data-handling software should be validated beforehand. The data-handlingfLC control software installation and IQ/OQ implementation, which are not addressed in this chapter, may take a considerable amount of time. This is often the case since this process typically involves an initial client/server implementation. 

The schematic arrangement of the MAS system is shown in Fig. 7.S. The autosampler will handle up to 40 samples which, when the parameters are defined, can be left to operate under computer control. The MAS system is configured complete to fit user requirements and includes both hardware and software facihties. 

Thermo Nuclean developed the segmented gate system (SGS) to segregate radioactive material from contaminated soil. The SGS is a combined system of conveyors, radiation detectors, software algorithms, and computer controls. The SGS diverts contaminated soil onto a conveyor belt that deposits the soil in a container for disposal or fnrther processing. The developer claims that the system removes minimal amounts of clean soil with the radioactive particles, reducing the amount of material requiring disposal. The SGS is commercially available. 

Computer control has been an essential part of STM ever since the very beginning. The different variations of computer interface and software are virtually unlimited. In this section, we describe the essential elements of computer interfaces. 

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