Jetting mechanism

In tanks where brick wall linings may not be desired, brick floors are sometimes installed in the bottoms to protect the bottoms (and perhaps the bag liner) from steam jets, mechanical abuse and the like. (Canadian Chemical Processing for September 3, 1980, Page 21, provides a case history of three rectangular creosoted Douglas Fir tanks, with 316 stainless tie rods, installed in 1958, and apparently still used by the purchaser at the date of publication for acid/sul-furic cleaning of copper and brass bars up to 50 feet in length. The units are lead-lined, with "acid brick" laid over the lead in the tank bottoms.)... 

The jetting mechanism propels small dots at rates up to 200 Hz in four software-controlled modes distance based, time based, fixed number of dots per line, and continuous line with breaks, enabling the construction of many different sizes and shapes of dots and lines. Because the momentum of the fluid comes from the jetting action, proximity to the substrate (dispense gap) is much less critical than it is in needle dispensing. 

The inherent simplicity of the jetting mechanism enables it to adapt to a wider variety of adhesive fluids, dispense patterns, and circuit board geographies than is possible with a needle dispenser. This simplicity facilitates multiple processes using a single jetting dispenser. 

For most users, the most attractive feature of jetting is the increased speed compared with needle dispensing. The primary reason for jetting to be faster than needle dispensing is the reduced amount of mechanical travel required by the jet mechanism. 

In another work by the same authors [14], a new correlation was proposed for subcooled jets (mechanical breakup) ... 

Jet injectors deliver insulin transcutaneously by an air-jet mechanism. The insulin solution or suspension is forced at high pressure through a fine nozzle, penetrates the skin without a needle, and creates a multitude of small depots. The dispersion of insulin deposited in the tissue explains the more rapid absorption of both rapid- and retarded-acting preparations (Taylor et al, 1981 Malone eta/., 1986 Houtzagerse/a/., 1988). Jet injection seems to affect the action profile of NPH insulin more markedly than that of the Lente t e insulins (Houtzagers et al, 1988). These devices are not painless and, in a European study, not well accepted by patients irrespective of the presence or absence of needle phobia (Houtzagers etal, 1988). However, in a more recent American study, the majority of patients preferred to take insulin by jet injector compared to needle injection (Denne et al, 1992). Jet injection has been found to be associated with a diminished antibody... 

In the expression for heating value, it is useful to define the physical state of the motor fuel for conventional motor fuels such as gasoline, diesei fuel, and jet fuels, the liquid state is chosen most often as the reference. Nevertheless, if the material is already in its vapor state before entering the combustion system because of mechanical action like atomization or thermal effects such as preheating by exhaust gases, an increase of usefui energy resufts that is not previously taken into consideration. 

A jet emerging from a nonciicular orifice is mechanically unstable, not only with respect to the eventual breakup into droplets discussed in Section II-3, but, more immediately, also with respect to the initial cross section not being circular. Oscillations develop in the Jet since the momentum of the liquid carries it past the desired circular cross section. This is illustrated in Fig. 11-20. 

Jet Aerators. Jet aerators are a cross between the diffused and mechanical aerators. Air and water are pumped separately under the water surface into a mixing chamber and ejected as a jet at the bottom of the tank or pond (Fig. 3f). Jet aerators are suited for deep tanks and have only moderate cost. Disadvantages include high operational costs, limitations caused by tank geometries, and nozzles that can clog. Additionally, they require blowers. 

In 1981, the Dutch company TNO in cooperation with the New Zealand government converted a gasoline engine to a flexible fuel vehicle by adding a fuel sensor. The sensor deterrnined the amount of oxygen in the fuel and then used this information to mechanically adjust the carburetor jets. 

Other Industrial Applications. High pressures are used industrially for many other specialized appHcations. Apart from mechanical uses in which hydrauhc pressure is used to supply power or to generate Hquid jets for mining minerals or cutting metal sheets and fabrics, most of these other operations are batch processes. Eor example, metallurgical appHcations include isostatic compaction, hot isostatic compaction (HIP), and the hydrostatic extmsion of metals. Other appHcations such as the hydrothermal synthesis of quartz (see Silica, synthetic quartz crystals), or the synthesis of industrial diamonds involve changing the phase of a substance under pressure. In the case of the synthesis of diamonds, conditions of 6 GPa (870,000 psi) and 1500°C are used (see Carbon, diamond, synthetic). 

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