Orifice diameter

As a consequence of these simple deductions, Graham s experiments c effusion through an orifice came to be regarded as one of the earliest direct experimental checks on the kinetic theory of gases. However, a closer examination of his experimental conditions reveals that this view is mistaken. As mentioned earlier, his orifice diameters ranged upwards from 1/500 in., while the upstream pressure was never very much less thai atmospheric. Under these circumstances the molecular mean free path len ... 

Viscometer Orifice length, mm Orifice diameter, cm Viscosity range, mm /s(=cSt) Approximate constants k K Main apphcations... 

To reflect this type of reasoning, a KBS captures quaHtative relationships between variables. By contrast, a conventional program that implements the flow equation calculates the value of the flow rate for numerical values of the input variables, ie, orifice diameter, orifice coefficient, and Hquid height. 

The orifice coefficient deviates from its value for sharp-edged orifices when the orifice wall thickness exceeds about 75 percent of the orifice diameter. Some pressure recovery occurs within the orifice and the orifice coefficient increases. Pressure drop across segmental ori-fiees is roughly 10 percent greater than that for concentric circular orifices of the same open area. 

The resulting motion of the beam is detected by the pneumatic nozzle amphfier, which, by proper sizing of the nozzle and fixed orifice diameters, causes the pressure internal to the nozzle to rise and fall with vertical beam motion. The internal nozzle pressure is routed to the pneumatic relay. The relay, which is constructed like the booster relay described in the Valve Control Devices subsection, has a direct hnear input-to-output pressure characteristic. The output of the relay is the controller s output and is piped away to the final control element. 

FIG. 10-18 Square -edged or sharp-edged orifices. The plate at the orifice opening must not be thicker than one-thirtieth of the pipe diameter, one-eighth of the orifice diameter, or one-fourth of the distance from the pipe wall to the edge of the opening, (a ) Pipe-line orifice, (h ) Types of plates. 

Increasing bed diameter increases spoutable depth. By employing a bed-orifice diameter ratio of 12 for air spouting, a 9-in-diameter bed was spouted at a depth of 65 in while a 12-in-diameter bed was spouted at 95 in. 

As indicated by Eq. (12-62) the superficial fluid velocity required for spouting increases with bed depth and orifice diameter and decreases as the bed diameter is increased. 

Single-Bubble Regime Bubbles are produced one at a time, their size being determined primarily by the orifice diameter d, the interfacial tension of the gasdiquid film C, the densities of the liquid Pl and gas Pc, and the gravitational acceleration g according to the relation... 

For bubbles formed in water, the orifice diameter that permits bubbles of about its own size is calculated as 0.66 cm. Davidson and Amick [AJChE J., 2, 337 (1956)] confirmed this estimate in their observation that stable bubbles in water were formed at a 0.64-cm orifice but could not be formed at a 0.79-cm orifice. 

Bubble sizes at formation generally increase with surface tension and orifice diameter. Prediction of sizes in swarms from multiple orifices is difficult. In aqueous solutions of low surface tension, Bubble diameters of the order of 1 mm are common. Bubbles produced by the more complicated techniques of pressure flotation or vacuum flotation are usually smaller, with diameters of the order of 0.1 mm or less. 

The condition for Knudsen effusion that tire irreair free path of tire effusate should be less tlrair the diameter of the circular orifice, limits the usable vapour pressure of the material in the Knudsen cell to about 10 Pa, since the orifice diameter would have to be less than 1 mm at a higher pressure. 

The flux of atoms emerging from a Knudsen cell at 1000 K in which an element of vapour pressure 10 " atmospheres and atomic weight lOOg is contained in a cell of orifice diameter 1 mm, is... 

Battelle (Seifert and Giesbrecht 1986) and BASF (Stock 1987) each conducted studies on exploding fuel jets, the former on natural gas and hydrogen jets, and the latter on propane jets. The methane and hydrogen jet program covered subcritical outflow velocities of 140, 190, and 250 m/s and orifice diameters of 10, 20, 50, and 100 mm. In the propane jet program, outflow conditions were supercritical with orifice diameters of 10, 20, 40, 60, and 80 mm. The jets were started and ignited after they had achieved steady-state conditions. 

In-cloud overpressure is dependent on outflow velocity, orifice diameter, and the fuel s laminar burning velocity. 

Figure 4.7. Maximum overpressure in vapor cloud explosions after critical-flow propane jet release dependent on orifice diameter (a) undisturbed jet (b) jet into obstacles and confinement.

Hydraulic diameter, or equivalent diameter, in. Orifice diameter, or nozzle opening, in. 

It is essential that the ASME code requirements be understood by the designer and individual rating and specifying the installation details of the safety device. It is not sufficient to merely establish an orifice diameter, since process considerations which might cause overpressure must be thoroughly explored in order to establish the maximum relieving conditions. 

Liquid orifices on tray pan usually at least 10 or more orifices per square foot of tower area. The orifice diameter can be determined [133] ... 

Liquid design height is usually one-half of the riser height. At minimum rates the depth on the tray can vary from in. to about 1 in. below top of riser height for maximum rates. The minimum orifice diameter is recommended at H in. diameter to overcome miscellaneous plugging of the holes [133]. Experience indicates the holes really should be % in. to avoid industrial plugging problems. 

D = Inside diameter of pipe, ft DH = Hydraulic diameter, ft d = Inside diameter of pipe, in. = d de = Equivalent or reference pipe diameter, in. dn = Hydraulic diameter, or equivalent diameter, in. dQ = Orifice diameter, or nozzle opening, in. 

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