Equipment malfunctioning

Gans, M., Systematize Troubleshooting Techniques, Chemical Engineeiing Piogiess, April 1991, 25-29. (Equipment malfunction examples)... 

Many processes require equipment designed to rigid specifications together with automatic control and safety devices. Consideration should be given to the control, and limitation of the effects, of equipment malfunction or maloperation including ... 

Maintenance "indicators" are available to help facility staff determine when routine maintenance is required. For example, air filters are often neglected (sometimes due to reasons such as difficult access) and fail to receive maintenance at proper intervals. Installation of an inexpensive manometer, an instrument used to monitor the pressure loss across a filter bank, can give an immediate indication of filter condition without having to open the unit to visually observe the actual filter. Computerized systems are available that can prompt staff to carry out maintenance activities at the proper intervals. Some of these programs can be connected to building equipment so that a signal is transmitted to staff if a piece of equipment malfunctions. Individual areas can be monitored for temperature, air movement, humidity, and carbon dioxide, and new sensors are constantly entering the market. 

We can consider a range of typical plant emergency situations which may result from utility failures, equipment malfunctions, or plant upsets, and which may result in equipment overpressure along with some guidelines for the evaluation of these emergency conditions and determination of reheving rates. 

In addition to equipment malfunctions which can cause process overpressure in associated equipment (e.g., overpressure in a fractionator due to failure of cooling water or reflux pump), certain support items to major processing... 

Building related illness (BRl) Any health problem related to poor air quality, due to equipment malfunction or contaminants in buildings. See also Sick building syndrome (SBS). 

Procedures dealing with the actions required in the event of equipment malfunction... 

What liazard is created if tuiy piece of equipment malfunctions ... 

Suppose that an explosion at a chemical plant could have occurred as a result of one of tliree mutually exclusive causes equipment nialfimction, carelessness, or sabotage. It is estimated tliat such an explosion could occur witli probability 0.20 as a result of equipment malfunction, 0.40 as a result of carelessness, and 0.75 as a result of sabotage. It is also estimated tliat tlie prior probabilities of the tliree possible causes of the explosion are, respectively, 0.50,0.35, and 0.15. Using Bayes tlieorem, deteniiine tlie most likely cause of the explosion. 

Let A, A., A denote, respectively, the events tliat equipment malfunction, carelessness and sabotage occur. Let B denote tlie event of the explosion. Tlien... 

If equipment malfunctions during the treatment process, adequate precautions should be taken to prevent the discharge of untreated effluent. Such precautions should be the provision of emergency collection tasks or the use of approved, licensed effluent-disposal traders. 

Within these tortuous systems there exists considerable opportunity for process contamination, corrosion, and equipment malfunction to occur, with cause-and-effect problems creating further impact downstream and placing additional demands on monitoring and control efforts. 

Figure 4.51. Distribution of experimental data. Six experimental formulations (strengths 1, 2, resp. 3 for formulations A, respectively B) were tested for cumulative release at five sampling times (10, 20, 30, 45, respectively 60 min.). Twelve tablets of each formulation were tested, for a total of 347 measurements (13 data points were lost to equipment malfunction and handling errors). The group means were normalized to 100% and the distribution of all points was calculated (bin width 0.5%, her depicted as a trace). The central portion is well represented by a combination of two Gaussian distributions centered on = 100, one that represents the majority of points, see Fig. 4.52, and another that is essentially due to the 10-minute data for formulation B. The data point marked with an arrow and the asymmetry must be ignored if a reasonable model is to be fit. There is room for some variation of the coefficients, as is demonstrated by the two representative curves (gray coefficients in parentheses, h = peak height, s = SD), that all yield very similar GOF-figures. (See Table 3.4.)...

Consider again a batch polymerization process where the process is characterized by the sequential execution of a number of steps that take place in the two reactors. These are steps such as initial reactor charge, titration, reaction initiation, polymerization, and transfer. Because much of the critical product quality information is available only at the end of a batch cycle, the data interpretation system has been designed for diagnosis at the end of a cycle. At the end of a particular run, the data are analyzed and the identification of any problems is translated into corrective actions that are implemented for the next cycle. The interpretations of interest include root causes having to do with process problems (e.g., contamination or transfer problems), equipment malfunctions (e.g., valve problems or instrument failures), and step execution problems (e.g., titration too fast or too much catalyst added). The output dimension of the process is large with more than 300 possible root causes. Additional detail on the diagnostic system can be found in Sravana (1994). 

A part of the test plan must include testing for the consequences of equipment malfunction, deviations in process conditions, and human error. Bench-scale equipment, for example, the RC1, is quite suitable for such experiments. By analysis of the process, critical conditions can be defined, which then need to be tested in order to be able to proceed safely from the laboratory to pilot plant studies. In testing abnormal conditions or process deviations, caution is required to assure that no uncontrollable hazard is created in the laboratory. Typical deviations, including impact on the process, are discussed in the following paragraph. 

Dataset C This data set is illustrative of data obtained with an equipment malfunction such that the response on one day was significantly different from the earlier day. Day one data regresses to a line parallel to day two data. Compare with Dataset B. 

Historically, companies and agencies that investigate incidents have overlooked human factor causes almost entirely. Material deficiencies in incidents (for example, equipment malfunction or a deficiency in the structural integrity of the vessel) can often he identified easily (for example, a shaft is broken). However, the real difficulty in incident investigation is to answer why these deficiencies occurred, and the answer is often related to human behavior. For instance, the shaft may have broken because of com-... 

Radioactive tracers [14] are a useful tool to measure unit parameters such as residence times and distribution of the catalyst and vapors in the reactor, stripper, or regenerator. Bypassing can be detected, slip factors calculated and dilute phase residence times are examples of useful calculations that can point the way to future modifications. This technology is also useful for detecting and analyzing equipment malfunctions. Plugged distributors, erratic standpipes, and main fractionator problems such as salt deposits or flooding can be detected with tracers. 

Significant changes in the facihties other than those currently reported must be closely examined. Any equipment used in the specific study must be examined to determine if it was standardized and calibrated prior to, during, and after use in connection with the study. It must be also determined—if at the time of the study there was equipment malfunction—the impact of the malfunction on the study and the remedial action taken. 

Most HPLC equipment currently available has a high tolerance to most mobile-phase conditions that can be contemplated for use in RPC applications with peptides. If it is intended to use mobile phases containing halide salts in RPC separations of peptides with standard HPLC equipment made from type 316 stainless steel, it is essential that the equipment is properly flushed with neat water when not in operation to avoid corrosion by the residual halide ions, especially at low pH. Otherwise, the use of the less popular biocompatible metal-free HPLC equipment, marketed by several manufacturers, avoids potential problems of equipment malfunction due to corrosion of the stainless steel or the contamination of peptide samples by low levels of leached metal ions. With such metal-free HPLC equipment, titanium, glass, or perfluoro-polymeric components have been used to replace any wettable stainless steel components. 

Typical irradiation facilities consist of a process chamber containing the radiation source, some sort of conveyor systems to transport products inside and outside the shielding walls, and sophisticated control and safety systems. Irradiation facilities are built with several layers of redundant protection to detect equipment malfunctions and protect employees from accidental exposure. Technical details depend on the type of irradiation. Typical processing parameters are compared in Table 2 [7]. 

The shortcoming of all methods for predetermining cure cycles that regulate secondary variables is that they deal only in expectations and probabilities. No matter how many eventualities are anticipated, there is always one more that is unexpected. Unexpected variations in material properties, process equipment malfunctions, and changes to geometries of tool and part all contribute to the uncertainty of the outcome. As a result, in-process, inferential control is needed for the process environment as well as the boundary conditions and material state. Inferential control is relatively new to the polymer processing industry, especially in complex processes where good models are not yet common. 

A narrow range is required and is generally acceptable if the variation is less than 10°C ( 2°F) of the mean chamber temperature. Significant temperature deviations greater than 2.5°C ( 4.5°F) of the mean chamber temperature may indicate equipment malfunction. Stratified or entrapped air may also cause significant temperature variations within the sterilizer chamber. Initially, a temperature distribution profile should be established from studies conducted on the empty chamber. Confidence may be gained through repetition, and therefore empty chamber studies should be conducted in triplicate in order to obtain satisfactory assurance of consistent results. 

In addition to production metering and automatic well testing, meter site automation detects equipment malfunctions such as high fluid levels in separators and site power outage. 

The difference in temperature between the coolest spot and the mean chamber temperature should be not greater than +2.5°C [7]. Greater temperature differences may be indicative of equipment malfunction. 

During one aerial application with XLR (experiment 4) the spray equipment malfunctioned. The applicator, in an attempt to correct the problem, accidently opened the dumping valve to the spray tank and the formulation splashed on him. The result was a total HDE of 367 mg/h, with almost half of it on the forearms. Since such an exposure would not be continuous, the calculation on an hourly basis is unrealistic. Therefore, the data were not used in determining the HDE to applicators. 

Equipment qualification—Definition of the equipment, system, and/or environment used for the process. These data are used to gather a baseline of the installation/operational condition of the system at the time when the performance qualification (PQ) of the system is performed. This baseline information is used to evaluate changes to the system performance over time. Intentional changes from these initial conditions must be considered and evaluated to establish that the system s performance is unaffected by the change. Unintentional changes in the form of a component or equipment malfunction or failure can be easily rectified using the available baseline data as a basis for proper performance. 

The FDA expects the phase I and phase II investigation efforts to proceed beyond the batch in question and to other batches that were also manufactured under the same circumstances leading to failure of the OOS batch. If the investigation has revealed an operator-related or process-related error (e.g., ingredient test failure, equipment malfunction, calibration expiration, irregularity in process execution) and other batches were made using one or more common elements, they should also be investigated for compliance with all acceptance criteria. In the case above, dissolution results should be scrutinized. 

Solids Removal. Some problems were found during the pilot plant operation which were directly related to the filtration step. The first problem was the filter cloth size. The initial filter cloth installed plugged with the solids causing equipment malfunction. 

When choosing instrumentation to place within the isolators, one should consider modularized instmmentation. By using modular instrumentation, parts of the instrument that do not have to be in direct contact with the sample can be located outside of the isolator. The benefits of this are twofold. The first benefit is that, by only placing the instrument modules that need to be in contact with the sample inside the isolator, one is effectively freeing up space in the interior of the isolator. This space can be utilized for additional analytical equipment or sample preparation. The second benefit is that, if the equipment malfunctions, you may only have to replace one module rather than the entire instrument. 

Other important physical measurements are bulk densities used to estimate hopper contents and circulation factors, and particle size analysis. The correct distribution of fine particles (30 - 180 microns) is essential to proper fluidization and transfer within the FCC unit. Generally, particles less than 30 microns are lost to the atmosphere or fines recovery system and are destined for a landfill. If the catalyst is too coarse, it may not circulate through the unit, necessitating a shutdown. Both problems are costly to the refiner and must be avoided. In addition, observation of particle size distribution changes at various points within the unit can pinpoint equipment malfunctions that might otherwise go undetected. 

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