Leak detection real leaks

From the table one can see that only helium leak detection with a mass spectrometer leak detector allows a real quantitative statement of leakage rates compliant with the requirements of the ISO 9000 series of standards for quality management. Therefore this method and its variants will be described in more detail in the following. 

A common area for a virtual leak is the mechanical mounting of a part on a surface the virtual leak is from the entrapped volume between the part and the sixrface. Virtual leaks are minimized by proper design and construction. The evacuation of virtual leaks is aided by heating. The determination of whether a leak is real or virtual may take appreciable detective work. One technique is to backfill with an uncommon gas such as neon. On pumpdown, if the neon peak in a mass spectrometer spectrum disappears rapidly, the leak is probably a real leak, but if it decreases slowly it is probably a virtual leak. 

New tank systems are also equipped with leak monitoring devices that take advantage of the double-walled construction. Leakage can be reported in real time and more accurately using these detection devices, which include water- or product-sensitive probes, or pressure detection devices if the space between the two walls is designed to remain under vacuum. 

In addition to the safety evaluation analyses of the IHTS for large leaks, R D work on sodium water reaction carried out to date includes small water leak experiments for the determination of a design base leak rate, development of reliable and real time detection system of water leaks using the acoustic signal as well as hydrogen detection, among others. Sodium fire characteristics and... 

However, the conunercial lAMS apparatus is too cumbersome for use in field analysis of air samples. Unfortunately, the commercial apparatus is not practical for the study of atmospheric environments. Therefore, to develop a new, compact and fieldable lAMS system by eliminating the differential pumping stage is desirable. The primary objeetive for the development was to design a system that can be easily transported to the field and that can detect any chemical species at atmospheric pressirre on a real-time basis. A single turbomolecular pump is employed as the vacuirm system to fill the basic requirements for vacuum conditions this is simple and cost effective. The optimal operation parameters for its use, the details and operation of the capillary leak inlet, and the system s analytical power in some preliminary applications are described also in this section... 

A compact ion attachment mass spectrometer was designed that is simple and small and fulfills all the basic requirements for lAMS the system can be used to obtain only molecular ions by detecting any chemical species in real time [93]. This custom-made apparatus (Fig. 6.11) consists of a Li+ ion attachment ion source into which a stream of gas from a capillary leak inlet is directed, an electrostatic lens system (ELS), and a quadrupole mass spectrometer and detector, all of which are installed in a vacuum-separated envelope. The system employs a single tuibomo-lecular pirmp on the vacuum envelope instead of a differential pumping system. 

The newly developed instrument has several important features. It accepts high capacity direct introduction of samples, operates with the atmospheric sampling device, and allows easy coupling of varions sample introduction sonrces to the mass spectrometer. It permits real-time detection of chemical species, possibly in-clnding radical intermediates and easy identification of compounds via the generation of ions that do not fragment. In addition, the capillary leak inlet system is simple and adaptable. In the near future, a large increase is expected in the use of lAMS for environmental and food chemistry research, especially in cases where... 

Another potentiometric method of measuring antibodies, or their complements, exploits the property of antigens to lyse erythrocytes sensitized through their fixation to the corresponding antibodies. The blood cell ghosts are loaded with trimethylphenylammonium cations (TMPA ), which act as markers. The liberation of these cations upon the action of the antigen is detected by an ion-selective electrode [244]. This method is impractical because the cations may leak out of the cells even in the absence of any antibodies, and there is a continuous and irreversible consumption of the marker. Other cations, such as tetrapentylammonium (TPA ), can be imprisoned in liposomes [245]. These electrodes cannot be considered as real biosensors since the immunological reaction occurs in solution, and there is no immobilization of an immunoreceptor on the electrode. 

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