Improving Reliability

Surveys have shown (Section 1.2) that many laboratories appear to be unaware of the poor quality of the results which they may be producing. Full awareness of the potential sources of error in the various aspects of laboratory work is undoubtedly the best stimulus to maintaining a high standard of accuracy and precision, and clinical chemistry laboratories should have their quality control data continuously available and under review. Control techniques have come into general use only comparatively recently, and their value may not yet be appreciated widely enough by the heads of laboratories. 

It will be increasingly possible in laboratory work to eliminate human error by the introduction of automation, at the price of growing capital expenditure on equipment. In order to make the best use of the expensive equipment involved, a trend toward the establishment of large, centralized laboratories that carry the analytical load for as large an area as possible is already being felt (Gl, W7). It will not be possible, however. 

Contact between the ward and laboratory staff is the best way of reducing most errors that occur before a specimen reaches the laboratory. The change toward larger laboratories, however, will inevitably mean a considerable decrease in the personal eontact that so many of the present small laboratories have with the staffs on the wards they serve. This loss need not increase errors in specimen collection if the possibility of its occurrence is recognized and steps are taken to overcome it. 

Each laboratory should make available to all its users a frequently updated set of detailed instructions for the collection of specimens and for the carrying out of all the tests done, together with information on the interpretation of results. No user should then have to rely unduly on his memory, nor should he have to obtain details on the carrying out of tests from textbooks, where many different descriptions of the same test are often to be found. The number of different containers for specimens should be kept to a minimum, and the label and request forms should be as simple as possible to expedite their proper completion the request form should include a space for entering the time of collection of the specimen. Possible ways of improving and simplifying request forms, and avoiding unnecessary transcription steps in the laboratory itself, have been considered by Lee and Schoen (L2a). 

Elimination of Clerical Errors in the Laboratory 5.3.1. Laboratory Reception 

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A recent design of the maximum bubble pressure instrument for measurement of dynamic surface tension allows resolution in the millisecond time frame [119, 120]. This was accomplished by increasing the system volume relative to that of the bubble and by using electric and acoustic sensors to track the bubble formation frequency. Miller and co-workers also assessed the hydrodynamic effects arising at short bubble formation times with experiments on very viscous liquids [121]. They proposed a correction procedure to improve reliability at short times. This technique is applicable to the study of surfactant and polymer adsorption from solution [101, 120]. 

This segment foeuses on the breaker trip event and how both the train speed and the differential pressure between the regenerator and reaetor stripper ean be eontrolled during this event. Based on the breaker status, aetion is immediately initiated on the expander. Due to the improved reliability in train operation with these patented eontrol teehniques, the PRT ean be better utilized without saerifieing plant reliability. This leads to more effieient FCCU operation and the pay-baek period for tlie improved eontrol system ean be extremely short. 

In many cases, the most frequent cause of equipment outage is the lubrication system. Because magnetic bearings do not wear out, and do eliminate oil, pumps, filters, coolers, and regulating and mixing valves, the potential for improved reliability is obvious. Reliability is also enhanced by the control system, which offers continuous real-time protection. The system automatically shuts down before machinery damage can occur. 

Fewer parts means improved reliability, fewer stoek eosts, fewer invoiees from fewer suppliers and possibly fewer quality problems. 

In many large power plants, refineries, and petroeliemieal eomplexes, about one-third of the failures are due to maehinery failure it is therefore neeessary to redesign parts of a maehine to improve reliability. 

Abemethy, R. B, Weibull Analysis for Improved Reliability and Maintain ability for the Chemical Industries, 3rd International Conference and Exhi bition on Improving Reliability in Petroleum Refineries and Chemical Plants, Organized by Gulf Publishing Co. and Hydrocarbon Processing, Houston, TX, November 1994. 

Are necessary emissions discharged safely and in accordance with good practice and legislation Can any unit or item be eliminated and does this improve safety, e.g. by reducing inventory or improving reliability ... 

When specifying compressor packages to API 1 IP, it may be necessary to specify certain sections of API 618 to ensure satisfactory installations. An example of this would be the supply of multiple compressors to be located in pipeline booster stations. In this case, an analog or digital pulsation and vibration study per API 618 Section 3.9 would be advisable to improve reliability and to minimize system problems and potential damage caused by gas pulsations and interaction between the individual compressor packages. 

The bulk of the information in the report is included in a 317-page appendix that contains systems descriptions, station blackout fault trees, diesel generator historical data, and diesel generator common cause failure analysis results for 18 different nuclear power plants. Tables and graphs are well organized and present data correlated to each plant studied. The study also contains conclusions and recommendations for improving reliability. 

Figure 7-9C. Armored graphite disk. Note steel ring bonded to circumference of disk to increase safety in toxic or fiammable services and improve reliability by preventing unequal piping stresses from reaching the pressure membrane. Teflon coatings or linings are available on the entire disk. By pemnission, Zook Enterprises.

The inverter drive system that uses a current-controlled rectifier and parallel-capacitor commutation operates to both improve reliability and reduce cost. Such systems are built commercially for the ranges from 20 to 500 hp for the typical 20 1 constant-torque speed range. 

A successful project is defined as one that meets its stated objectives (safety, improved reliability, increased liquid yield, reduced maintenance costs, etc.) on or under-budget and is completed on or ahead of schedule. Some of the helpful criteria that ensure a successful project are as follows ... 

Improved reliability of equipment, but much still to be done Maintenance costs often too high Desire to go more automatic and on-line Awareness that system installation is expensive Continuing interest in new techniques... 

As part of a 3-year contract with EPA, the Research Triangle Institute is conducting research to improve EPA Cyanide (335.x) Methods. EPA Method 335.2 has many interferences, and the laboratory is evaluating known interferents. In addition, modifications to reduce the time per analysis, lower detection limit, and improve reliability will be evaluated. 

The effort to carry out all these balances is high, but it significantly increases the reliability of the results, that should be based not only on single measurements (analyses). Usually, incorrect data are only detectable on the basis of at least two independent values or balances. If various balances are found, often an error can be identified as a false measurement or analysis mistake and not a real failure. As far as possible, several samples should be taken during each experiment for improved reliability. For continuous operation under stationary conditions, the average of some measurements and analyses will be used (any tendency in the individual values shows that the stationary state is not yet achieved). In case of batch operation a consistent change with time confirms reasonable results (here, in the mass balance the decrease of the cell liquid by the sampling has to be considered). 

Discussions with the only US. PAFC manufacturer justified the direct use of the PAFC performance information from the 1994 edition of the Fuel Cell Handbook. There have been only minor changes in cell performance, mostly due to changing the operating conditions of the cell. These are considered within the performance trends shown in this section. The manufacturer has concentrated on improving cell stability and life, and in improving the system components to improve reliability and lower cost. It should be noted that the performance shown in this section is based on information from contracts that the manufacturer had with the Department of Energy or outside institutions. Any new PAFC performance has been accomplished with company funding and is considered proprietary by the manufacturer (1). 

Now let us look at the systems and the components of the systems. Reports in the field are virtually mute on many small but annoying problems, which almost invariably accompany the operation of seawater RO systems. Here are some which have plagued us, starting with the pumps. I will not identify manufacturers, as I have avoided reference to any in this writeup. It is not my objective to accuse anyone. I just offer these comments in the hope to encourage those who I hope are aware of their product problems in the field and failures to rectify those for the benefit of all. I feel that considerably greater attention must be placed on pumps and pump materials selection for seawater RO use in order to improve reliability, simplify maintenance, and reduce failure frequency in the pump operations, and in turn improve on the RO system water supply capability. 

Combustion control is currently a hot area of research in the U.S. and abroad. In addition to basic research at a number of universities, joint industry-university S T efforts are also underway to implement the control strategies developed by researchers in industry applications. Though some of the demonstrations have been made using gaseous fuels, the techniques can be extended to liquid fuels as well, and efforts are underway to accomplish this. It is hoped that future engines will perform equally well in off-design conditions, with improved reliability and easier maintenance, and reduced operational costs. 

Newer ESPs with rigid electrodes and unitized collecting plates provide improved reliability compared to weighted wire units. Designing a unit with multiple independent electrical sections allows a portion of the ESP to be taken out of service while remaining online. 

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