Reed contacts

Magnetic reed contacts are glass-encapsulated magnetically operated reed switches used on doors and windows. The contacts can be overcome by cutting the door, leaving the magnet undisturbed. 

Salt level Reed contact + swimmer Density sensors... 

Fig. 5.6 The basic operation of a reed switch under the influence of the magnetic field of a permanent magnet. The polarization of the reed blades occurs in such a manner to offer an attractive force at the reed contacts.

The bombing test is use to check the tightness of components which are already hermetically sealed and which exhibit a gas-filled, internal cavity. The components to be examined (e.g. transistors, 1C housings, dry-reed relays, reed contact sw/itches, quartz oscillators, laser diodes and the like) are placed in a pressure vessel which is filled with helium. Operating with the test gas at relatively high pressure (5 to 10 bar) and leaving the system standing over several hours the test gas (helium) will collect inside the... 

Generally, the encapsulation shall be made without voids. But it is permitted to encapsulate components (relays, Reed contacts) each designed with an internal free volume up to 100 cm3. The thickness of compounds between such components shall be at least 3 mm (for very small internal free volumes <1 cm3, the thickness may be reduced to 1 mm). 

Figure 6.186(a) Hydraulic cylinder with integrated piston stroke sensor. The stroke sensor fixed at the cylinder bottom, a tube made of stainless steel, contains a chain of resistors and, connected to these, an adequate number of Reed contacts activated by a piston-integrated annular-shaped permanent magnet. A magnetically activated Reed contact works like the tap of a potentiometer. 

There are a good number of digital inputs interfaced with the DCS through safety systems. Mostly, these inputs come from mechanical or reed contacts, transistors, limit switches, pushbuttons, etc. All these are simple apparatus and do not need any certification by a third party. There are two ways digital inputs for IS applications are handled, either a switching amplifier (NAMUR sensor) or by grounded IS barrier. 

The special feature of the Olin-Mathieson cell lies in the system of mounting and adjusting the anodes. Above each row of anode rods, a U-shaped copper or aluminum bus bar also serves to support the anode lifting gear. The anode rods are bolted to the U-shaped bus bar. The anodes are adjusted as a group, either manually or by a remote computer with the remote computerized anode adjuster (RCAA) system. The currents are measured independently of the cell potentials by means of reed contacts [90]. 

For ruthenium, electrolytes based on ruthenium sulphamate or nitrosyl-sulphamate have been described, but the most useful solutions currently available are based on the anionic complex (H2 0 Cl4 Ru N Ru-Cl4-OH2) . The latter solutions operate with relatively high cathode efficiency to furnish bright deposits up to a thickness of about 0-005 0 mm, which are similar in physical characteristics to electrodeposited rhodium and have shown promise in applications for which the latter more costly metal is commonly employed. Particularly interesting is the potential application of ruthenium as an alternative to gold or rhodium plating on the contact members of sealed-reed relay switches. 

Fig. 5.18 Dropping the reed switch on a hard surface can induce several 100 Gs to the contacts many times altering the switch characteristics.

A direct-contact gas cooler system operates as follows Approximately 35,000 lb/hr of bone-dry air is passed over hot trays. The air is heated from 150°F to 325°F as it passes over the trays. It exits from the unit with a due point of 105°F. The hot air is sent to a direct-contact cooler, where its temperature is reduced back to 150°F. During the cooling stage, the air is dehumidified with water that is heated frpm 75°F to 105°F. The unit is rated at 3.5 inches of water pressure drop (a) Determine the number of diffusion units needed for this operation and (b) Establish the required dimensions for the direct-contact cooling tower (Hint Use standard low-pressure-drop data from the literature. Some of the older literature give pressure drop data for simple fill. See Sherwood, T. K. and C. E. Reed [6]. 

CONTACT POTENTIAL FROM VIBRATING REED ELECTRODE STUDIES... 

Cooper SM, Reed J, Shaw S. Systemic reaction to nystatin. Contact Dermatitis 1999 41(6) 345-6. 

There are two practical difficulties. One is the measurement of the very small photocurrent, which may be as low as 10" amp, requiring the use of a vibrating reed electrometer or similar instrument. The second is that, for work functions above 5 eV, Vq lies in the far ultraviolet. This makes the study of some adsorptions very difficult and 6 eV is about the practical limit of such measurements. A suitable light source is the quartz mercury arc. The energy of the incident beam can be measured with a calibrated photocell, a vacuum thermopile or a radiometer. A suitable cell for adsorption studies is shown in Fig. 11. The sample being studied forms the cathode B. It can be a metal foil or a film formed by evaporation from the filament E. A wire C is fused through the glass to make contact with the... 

Kitamura K+,J Dermatol 20, 279 (psoriasiform) (31%) (1993) Sousa-Basto A+, Contact Dermatitis 29, 44 Stevens-Johnson syndrome (1998) Knowles S +, J Am Acad Dermatol 38, 201 (passim) (1993) Sanders CJ +, Lancet 341, 967 Subcorneal pustular dermatosis (Sneddon-Wilkinson) (2001) Reed B, Denver, CO (from internet) (observation)... 

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