Hermeticity of the end seals

The hermeticity of the end seals of the capacitor. No joint is one hundred percent perfect, and some evaporation will take place slowly over time. We see the need to pick a vendor with a high (and consistent) quality. Yes, in principle, we could try to seal the capacitor totally, say by immersing it in a bath of epoxy-resin/ superglue for example But such capacitors are designed to vent under high pressure (much like a pressure cooker). However, I must tell you that despite all that safety chatter, I have seen some capacitors explode furiously. Remember, it once happened to me in Bombay ... 

When metal inserts require hermetic sealing, consider coating them with a flexible elastomer such as an RTV rubber, polyurethane, or epoxy system. A second method is to design an annular space or reservoir at one end of the insert from which to dispense the flexible elastomers to effectively create a hermetic seal. Flexible sealants are also used to compensate for differences in the thermal coefficient of expansion between metal and plastic. 

Fluid Actuator. A new actuator, called PyrAc, is a low cost fluid dispenser or fluid power supply powered by a pyrotechnic charge. It is non-fragmenting and is hermetically sealed. The device consists of two concentric tubes sealed at the end with a pyrotechnic charge in the inside of the fluted inner- tube. The space between the fluted section and the... 

At the end of the operation the heating is discontinued and the chlorine expelled from the apparatus by a rapid current of carbon dioxide. The salt is now rapidly transferred to a tube and hermetically sealed. 

Cans may either be three piece consisting of a body made up of a welded cylinder with one end seamed in place which is then closed with a second end, or two piece consisting of a body formed from a single piece of metal closed with an end (see Fig. 11.1). Aluminium cans are always two piece whereas steel cans may be either three piece or two piece . The end or ends are seamed onto the can body which involves the forming of a double seam of folded metal (see Fig. 11.2). A hermetic seal (a key element of metal food and beverage packaging) is ensured by the incorporation of a... 

Storage conditions depend on the end use for the product, the packaging system, and the desired storage time. Milkfat in hermetically sealed cans and dmms is the least affected by its storage environment. Ambient storage is commonly used and must be to the same standards as used for other food smffs (122). In the European community and the United States, temperature is not a major factor, but it can be in tropical countries, where the temperature may rise to 35 0°C. At temperatures in excess of 30°C, the milkfat deteriorates significantly more rapidly, and there is an increased risk that the stored fat will have a stale, oxidized off-flavor. 

Which technique to use generally depends on the desired reliability during end-use operation. Certain military applications, for example, will demand expensive hermetically sealed packages, whereas an inexpensive calculator may make do with a simple glob of encapsulant on top of the chip. 

Crystal Scintillation Detector. The well detector is a common type of a crystal scintillation detector and has a hole drilled in the end or side of the cylindrical crystal to accept a test tube. Because it is hygroscopic, the crystal is hermetically sealed in an aluminum can with a transparent quartz window at one end through which the blue-violet (420 nm) scintillations are detected. The photons of gamma emitters, such as Cr, Co, Fe, and (Table 1-14) in the sample easily penetrate the specimen tube and the thin, low-density can and enter the crystal where they are likely to... 

Low-viscosity liquids can be transferred to the hermetic DSC pan using a Pasteur-pipette or similar apparatus. Dipping one end of an opened paper clip into viscous liquids and then placing it onto the base of the sample pan may transfer higher viscosity samples. Care should be taken not to contaminate the lip of the pan with any liquid as this will result in a poor seal. 

Rubber closures for vials or other containers being filled aseptically on an industrial scale are nonporous but share some of the problems of porous loads. They are most frequently steam sterilized by passage through double-ended rotary washer autoclaves, which by agitation of the product ensure effective steam penetration to even the potentially occluded parts of the closures. Steam comes into direct contact with these bulk items they are not usually wrapped nor packed into hermetically sealed containers. Special precautions must be taken for unloading to avoid compromising their sterility. Static autoclaves may also be used for prew ashed versions of these types of components. They should then be loaded into the autoclave in shallow layers in perforated trays or boxes. 

Each see has a bulge called the ampulla near one end, and inside the ampulla is the cupula, which is composed of saccharide gel, and forms a complete hermetic seal with the ampuUa. The cupula sits on top of the crista which contains the sensory receptor cells called hair cells. These hair cells have small stereocilia (hairs) which extend into the cupula and sense its deformation. When the head is rotated the endolymph fluid, which fills the canal, tends to remain at rest due to its inertia, the relative flow of fluid in the canal deforms the cupula hke a diaphragm and the hair cells transduce the deformation into nerve signals. 

Detactor tubes—are probably, the simplest (and least accurate) of the direct reading instruments. The detector tubes are often referred to by the name of their manufacturer, such as Drager or Sensidyne tubes. The detector tube is hermetically sealed at both ends and filled with a granular or powdery reagent. Each tube is specific for a particular gas or vapor, hence tubes for ammonia detection are different from the tubes for carbon monoxide or methane detection. Each tube has printed on it s surface the name of the chemical it is specifically designed to test for. 

---