Chemical apparatus and process disinfecting – deodorizing – preser – Analyzer – structured indicator – or manipulative laboratory... – Means for analyzing liquid or solid sample
Reexamination Certificate
2000-03-17
2002-04-02
Ludlow, Jan (Department: 1743)
Chemical apparatus and process disinfecting, deodorizing, preser
Analyzer, structured indicator, or manipulative laboratory...
Means for analyzing liquid or solid sample
C073S023420, C073S061560, C096S105000, C096S106000, C210S198200, C422S089000, C422S105000
Reexamination Certificate
active
06365105
ABSTRACT:
In a GC the fluid is in the form of gas. Samples of fluid under test are typically under the control of control devices such as pumps, valves, pressure transducers and pressure regulators. The control devices help in the acquisition of samples, and the isolation, handling and separation of the samples during the process of chemical analysis. In a GC, a sample aliquot is directed, either manually or automatically, through a complicated array of plumbing hardware and control systems that that perform various functions before the sample flows through one or more separation columns. In the separation columns different compounds in the sample fluid are isolated. As the isolated compounds flow out of the columns they flow through detectors of various kinds that assist in identifying and quantifying the compounds.
As a sample flows through an instrument such as a GC it may be exposed to various other fluids such as carrier fluids, calibration fluids and the like. Moreover, the fluid flow paths include many junctions and intersections. At each step along the processing path where fluids are rerouted or further isolated, the fluid flows through a variety of plumbing hardware and control systems.
It is obvious that in many analytical instruments that require controlled fluid flow there are numerous fluid flow paths, and complex hardware systems that include tubing, barbs, couplings, valves, sensors, pumps and regulators of various kinds. The plumbing systems in even relatively simple instruments such as some gas chromatographs can become exceedingly complicated, not to mention the complexity added by the fluid control systems.
Precision, reliability and accuracy are of course primary goals of any analytical analysis. As such, it is essential in an analytical instrument to eliminate, or at least minimize, all sources of system failure, including problems such as leaking fittings that can adversely effect the analytical processing. The complexity of the plumbing and fluid controlling hardware of many analytical instruments presents a situation that is at odds with the fundamental principles of accuracy and precision that such instruments rely upon. Accurate analytical results require accurate fluid processing, without system failures such as non-fluid-tight couplings. But every fitting, connection, interconnection and fluid-controlling device in an analytical instrument introduces a potential site for a problem such as a leak. When even a small leak occurs in a critical connection the accuracy of analytical test data is compromised. In an instrument that contains dozens of couplings and connections the opportunity for incorrectly connected fittings is multiplied many times over.
The problems described above with respect to complicated fluid connections are well known to any laboratory technician who has operated an analytical instrument such as those described. Even in the relatively idealized conditions of a modern laboratory, and even with laboratory grade instruments, plumbing problems are a constant source of trouble with analytical instruments such as GCs. As such, there is a great benefit in reducing the number and complexity of fittings in an instrument that uses fluid flow.
But the problems noted above are even more pronounced with analytical instruments that are designed for use in the field rather than in a controlled laboratory environment. There are several reasons. First, field instruments tend to be smaller since portability may be a primary goal. As the instruments get smaller so do the fittings and connections. With miniaturized hardware it is more difficult to ensure fluid-tight processing. Second, an instrument designed for use in the field is often subject to more extreme environmental conditions and rougher handling. In many respects, therefore, field units need to be even more robust than their laboratory counterparts. This can be a difficult objective when another goal in designing the unit is reduction of size.
A relatively newer type of analytical instrument is an in-situ monitoring device that is installed in place to monitor on an ongoing basis some kind of processing activity. Such devices are often designed to interface with telephony equipment for automatic transmission of analytical data and for remote access to central processing units in the instruments. These devices may be left in the field for extended periods of time, and do not have the benefit of the constant monitoring and maintenance that both laboratory and portable instruments might enjoy. In-situ instruments therefore must be extremely rugged to provide reliable data over an extended period of time.
In-situ instruments also may be placed in extreme environmental conditions that test the limits of hardware design. For instance, such devices may be subjected to wide fluctuations in ambient temperature and other extremes in weather conditions, and to harsh chemical environments. Design engineering must take these conditions into account. But in instruments that include complicated plumbing schemes it is even more difficult than in laboratories to minimize chances for leaking fittings and the accompanying errors in obtaining reliable data.
In situ monitoring and reporting of dissolved gasses in dielectric fluid blanketed electric power transformers is one example of a situation where an in situ analytical instrument is desirable, but where technical difficulties have made such instruments difficult to design. Some kinds of large electrical transformers and other electrical power transmission and processing devices utilize dielectric fluids such as transformer oil to cool and insulate the components. With respect to transformers, various operating events and conditions can cause transformer components, such as insulating paper, and the insulating oil itself to degrade. For example, incipient transformer faults such as arcing and partial discharge can lead to transformer oil breakdown. Thermal faults can cause both oil and cellulosic decomposition. Regardless of the cause of such faults, they often result in the production of contaminants such as combustible gases including low molecular weight hydrocarbons, carbon monoxide and dioxide, and other volatile compounds, which are diffused into the oil. As a result, the insulating and cooling properties of the insulating oil are altered, diminishing the transformer's efficiency and promoting transformer failure.
The presence of so-called fault gasses in oil-blanketed transformers and other devices has well documented implications relating to the performance and operating safety of the transformer. There is a substantial body of knowledge available correlating the presence of fault gasses with certain, identified transformer conditions and faults. It is therefore beneficial to monitor the condition of dielectric fluids in equipment such as transformers in order to maximize transformer performance, while at the same time minimizing wear and tear on the transformer, and thereby minimizing maintenance costs. Thus, information relating to the presence or absence of certain fault gasses in transformer oil can lead to greatly increased efficiency in the operation of the transformer.
As noted, the presence of some fault gasses in transformers can lead to dangerous conditions. It has been well documented that the presence of some kinds of fault gasses in transformer oil can be indicative of transformer malfunctioning, such as arcing, partial or corona discharge. These conditions can cause mineral transformer oils to decompose, generating relatively large quantities of low molecular weight hydrocarbons such as methane, and some higher molecular weight gasses such as ethylene and ethane. Such compounds are highly volatile, and in some instances they may accumulate in a transformer under relatively high pressure. This is a recipe for disaster. Left undetected or uncorrected, these explosive gasses can lead to an increased rate of degradation, and even to catastrophic explosion of the transformer. Transformer failure is a significantly expensive event for an elect
Bushnell Raymond
Waters Thomas
ipsolon llp
Ludlow Jan
Serveron Corporation
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