Reduced flow orifice

These cabinets are automated-purge cabinets with redundant safety features such as excess-flow sensors, reduced-flow orifices, and system-failure shutdown protocols. They utilize high-turbulence constmction with high exhaust flow—200 cubic feet per minute at 0.02 inches of water pressure differential. These are monitored by automated sensors and manometers with a visual readout at the cabinet location. All cabinets contain fire sprinklers (Figures 8.15 and 8.16). 

Another safety device that is available as part of the cylinder valve is the reduced flow orifice. This orifice is made of a small plug that is installed into the cylinder valve outlet, and has a very small hole drilled through it to limit the flow of gas through the valve. Should the cylinder valve or components downstream of the cylinder develop a leak, the reduced flow orifice would limit the rate of that leak to a lower flow than would occur through the imrestricted cylinder valve outlet. A lower flow leak is more easily handled by safety personnel, ventilation systems, and gas abatement systems. 

The spring ensures a soHd closing action and is usually wound from stainless steel wire. The dip tube conducts the product from the container to the valve. It is usually extmded from polyethylene or polypropylene and has an inside diameter of over 2.54 mm, although it can be provided in capillary sizes having diameters down to 0.25 mm. These small tubes are used to reduce flow rate and may function in place of the Hquid metering orifice in the valve housing. 

This curve is seen where a large airway has a fixed orifice through which gas is able to flow, such as may be seen in patients with tracheal stenosis. The peak inspiratory and expiratory flow rates are, therefore, dependent on the diameter of the orifice rather than effort. The curves should be drawn almost symmetrical as above, with both limbs demonstrating markedly reduced flow. The TLC and RV are generally unaffected. 

Ouibrahim and Fruman (47) in 1980 found dilational flow in three distinct flow situations, which each involve an extensional component capillary tube flow, orifice flow, and pitot tube flow. They examined extensively hydrolyzed polyacrylamide (HPAA) and found that the dilatant effect was greatly reduced in the presence of excess salt. This finding was attributed to the effect of the salt ions in screening the charges on the polyelectrolytic HPAA and thus causing the contraction of the highly expanded molecule. 

Most CGA valves are provided with a restricted flow orifice (RFO). The restricted flow orifice is the most important contribution to silane safety. It will reduce an unrestricted orifice to a maximum orifice size ranging from 0.006 inches to 0.015 inches. It is desirable to limit the flow to 30 liters per minute. With silane, some process engineers argue that these orifices clog. At the 1990 Semiconductor Safety Association Conference, a semiconductor manufacturer indicated they recorded 1600 points without a single incident of clogging. The use of die restricted flow orifices with... 

Enough space must be available to properly service the flow meter and to install any straight lengths of upstream and downstream pipe recommended by the manufacturer for use with the meter. Close-coupled fittings such as elbows or reducers tend to distort the velocity profile and can cause errors in a manner similar to those introduced by laminar flow. The amount of straight pipe required depends on the flow meter type. For the typical case of an orifice plate, piping requirements are normally Hsted in terms of the P or orifice/pipe bore ratio as shown in Table 1 (1) (see Piping systems). 

The aperture impedance principle of blood cell counting and sizing, also called the Coulter principle (5), exploits the high electrical resistivity of blood cell membranes. Red blood cells, white blood cells, and blood platelets can all be counted. In the aperture impedance method, blood cells are first diluted and suspended ia an electrolytic medium, then drawn through a narrow orifice (aperture) separating two electrodes (Fig. 1). In the simplest form of the method, a d-c current flows between the electrodes, which are held at different electrical potentials. The resistive cells reduce the current as the cells pass through the aperture, and the current drop is sensed as a change in the aperture resistance. 

The two principal elements of evaporator control are evaporation rate a.ndproduct concentration. Evaporation rate in single- and multiple-effect evaporators is usually achieved by steam-flow control. Conventional-control instrumentation is used (see Sec. 22), with the added precaution that pressure drop across meter and control valve, which reduces temperature difference available for heat transfer, not be excessive when maximum capacity is desired. Capacity control of thermocompression evaporators depends on the type of compressor positive-displacement compressors can utilize speed control or variations in operating pressure level. Centrifugal machines normally utihze adjustable inlet-guide vanes. Steam jets may have an adjustable spindle in the high-pressure orifice or be arranged as multiple jets that can individually be cut out of the system. 

Spray characteristics of pressure nozzles depend on the pressure and nozzle-orifice size. Pressure affects not only the spray characteristics but also the capacity. If it is desired to reduce the amount of liquid sprayed by lowering the pressure, then the spray may become coarser. To correct this, a smaller orifice would be inserted, which might then require a higher pressure to produce the desired capacity, and a spray that would be finer than desired might result. Multiple nozzles tend to overcome this inflexible charac teristic of pressure atomization, although several nozzles on a diyer complicate the chamber design and air-flow pattern and risk collision of particles, resulting in nonuniformity of spray and particle size. 

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