Leakage flow-rate

If leakage flow-rate Qieak is laminar, then... 

The velocity in the down-channel direction, Fig. 10.15(a), indicates that most of the fluid undergoes circulatory flow, as expected. A circulatory flow is also generated in the plane perpendicular to the helical surface of the C-shaped chambers, Fig. 10.15(b). Velocity vectors indicating calender-gap leakage flows, Qc, are shown, without using them to obtain leakage flow rates. The interaction between the two circulatory flows eliminates the possibility of a stagnant layer at y/H = 2/3. 

Qi Leakage flow rate in a counter rotating intermeshing twin screw extruder... 

Clearances associated with seals and pressure leakages are considered orifices, and the leakage flow rates are computed using the following ASME orifice formulas with the known seal gap flow areas Aas as follows. 

In the case of a very large leak through a valve the leakage flow rate can be determined using standard methods of flow measurement with radiotracers. 

Seal leakage flow rates, measured by the time taken to fill a graduated container. 

Fig. 4. Hypothetical leakage curves to show effect of ionic concentration and flow rate, where the dashed line corresponds to the leakage shutdown level...

Table 9.11 gives the upper limits of the leakage volume flow rate for the three ductwork classes at typical test pressures. 

For small downdraft tables used for chemical work, a flow rate of 0.28 m s and m- table is used. This gives a mean velocity immediately above the surface of approximately 0.3 m s h This is a very low velocity, which can not capture moving contaminants. When these values are used, a maximum use height of 0.15 m is recommended, which should result in a small leakage from the source to the surrounding. This presumes there is at least 0.1 m of uncovered surface between the worker and the source and that the surface is covered to less than 30%. For these tables the pressure difference is between 50 and 100 Pa, depending on the density of holes. ... 

According to Mitchell" the auxiliary flow rate should be between 20% and 40% of the total exhaust flow rate from the cupboard below 20% results in only small improvements and above 40%, leakage rises quite fast with in creasing flow rate. 

Glove boxes have been described in Section 10.2.3.6 as systems with only exhaust air. There are glove boxes with both supply and exhaust air openings inside the closed volume (see Section 10.4.6.4) that look and function like the boxes described earlier. The use of supply air directly to the closed volume means that the control of the flow rates must be very accurate. Otherwise the box may be at a higher pressure than the surrounding areas, resulting in leakage of contaminants. 

The simplest calibration procedure for a gas flow-measuring device is to connect it in series with a reference meter and allow the same flow to pass th tough both instruments. This requires a reference instrument of better metrological quality than the calibrated instrument. One fact to consider when applying this method is that the mass flow rate in the system containing both instruments is constant (assuming no leakage), but the volume flow rate is not. The volume flow rate depends on the fluid density and the density depends on the pressure and the temperature. The correct way to calibrate is to compare either the measured mass... 

Wv = Pounds water vapor per pound air w = Constant flow rate, lbs/min wa = Acceptable air leakage rate assigned to a system component, lbs/hr... 

Compliance with U.S. EPA s design performance standards can be demonstrated through one-dimensional, steady-state flow calculations, instead of field tests. For detection sensitivity, the calculation of flow rates should assume uniform top liner leakage. For detection time, factors such as drain spacing, drainage media, bottom slope, and top and bottom liners should all be considered, and the worst-case leakage scenario calculated. 

Leakage through a synthetic liner is controlled by Fick s first law, which applies to the process of liquid diffusion through the liner membrane. The diffusion process is similar to flow governed by Darcy s law except that it is driven by concentration gradients and not by hydraulic head. Diffusion rates in membranes are very low in comparison with hydraulic flow rates even in clays. In synthetic liners, therefore, the factor that most influences liner performance is penetrations. Synthetic liners may have imperfect seams or pinholes, which can greatly increase the amount of leachate that leaks out of the landfill. 

A plant handling substantial quantities of flammable toluene is located 1000 ft from a residential area. There is some concern that a sizable leak of flammable vapors will form a flammable cloud with subsequent ignition in the residential area. Determine the minimum mass flow rate of toluene leakage required to produce a vapor cloud in the residential area with a concentration equal to the LFL. Assume a 5 mph wind and D atmospheric stability. 

It is particularly difficult when the gradient nano LC flow rate is below 1 /tL/min at which any small plumbing leakage could significantly affect retention time and gradient reproducibility. A 3 cm capillary column packed with 1.5 to 3 /tm particles can be run at a high flow rate to reach... 

The volumetric flow rate Q (leakage rate) of a fluid in laminar flow through a high aspect ratio (h/w 1) rectangular duct (i.e., the seal volume) of width, w, height, h, and path length, z, in the flow direction is given by ... 

Generally, the absolute magnitude of Q is not as important as the ratio leak rate to the total flow rate Qieaf/QtotJ. The leakage rate given by Equation (5.4) is the volume flow rate at the temperature and pressure of the leakage flow, and must be corrected to standard conditions for comparison with reactant feed rates. The total required flow rate of fuel or air to the stack is proportional to the stack current, which increases with the electrochemically active area and is inversely proportional to the cell area specific resistance (R"). 

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