Pressure imbalance

Process Flow The schematic in Fig. 22-56 may imply that the feed rates to the concentrate and diluate compartments are equal. If they are, and the diluate is essentially desalted, the concentrate would leave the process with twice the salt concentration of the feed. A higher ratio is usually desired, so the flow rates of feed for concentrate and feed for diluate can be independently controlled. Since sharply differing flow rates lead to pressure imbalances within the stack, the usual procedure is to recirculate the brine stream using a feed-and-bleed technique This is usually true for ED reversal plants. Some nonreversal plants use slow flow on the brine side avoiding the recirculating pumps.. Diluate production rates are often 10X brine-production rates. 

It is not recommended to place an elbow at the suction of any pump (Figure 16-2, next page). This will cause a turbulent flow into the pump. If elbows are needed on both sides of the pump, you should u.se long radius elbows with flow straighteners. You should have 10 pipes diameters before the first elbow on the suction piping (Example If the pump has a 4 inch suction nozzle, you should respect 40 inch of straight pipe before the first suction elbow.) Short radius elbows cause vibrations and pressure imbalances that to lead to wear and maintenance on the pump. 

FIGURE I Abnormal e-gram due to pressure imbalance at anode and cathode. 

It is this property that drives the process of self-emulsiLcation. Mechanisms for promoting self-emulsiLcation are a topic of current study (Pouton, 1997 Buchanan etal., 2000 Nishimi and Miller, 2000 Shahidzadeh et al., 2000 Lo pez-Montilla et al., 2002). The mechanisms most likely involved in dispersion of pharmaceutical formulations are diffusion and stranding, those driven by osmotic pressure imbalances (Greiner and Evans, 1990), phase transformations, and changes due to alteration of environmental conditions (e.g., pH). Given the number of components found in pharmaceutical formulations, it is not unexpected for several mechanisms to operate in parallel. 

If the external pressure is suddenly decreased by dP, the piston moves out due to the pressure imbalance (Refer to the following figure). 

An integrated microfabricated cell sorter has been constructed using a control layer and a fluidic layer fabricated on PDMS [890]. The control layer consists of valves that will be pneumatically controlled by pressurized N2. This device is superior to an electrokinetic sorter, which suffers from buffer incompatibilities and frequent voltage adjustments because of ion depletion or pressure imbalance due to evaporation. E. coli cells expressing EGFP were sorted and selected out from a cell mixture which also contained E. coli cells expressing the / -nitrobenzyl (PNB) esterase. About 480,000 cells have been sorted at a rate of 44 cefls/s in 3 h. The recovery yield was 40% and the enrichment ratio was about 83-fold [890]. 

Room pressure imbalance between adjacent cubicles which are linked by common dust extraction ducting should be prevented. 

Using an instrument (such as strain gauges) that is mounted on or at the end of tie bars to measure any pressure imbalance on the mold due to imbalance in apphed clamping pressures via the tie bars. See measurement strain gauge. 

Figure 2.4 Schematic diagram of the double-headed piston-cylinder apparatus. To move the piston, any pressure imbalance between the methane and air chambers must overcome friction at the surfaces of contact between the piston heads and cylinder walls.

Process 1 Finite stepwise irreversible expansion. From the initial conditions, we want to expand the methane to 1.1 bar. To create a pressure imbalance across the piston, we vent the air chamber. In this first example, air is removed by cycling the ball valve open and shut three times. During each cycle enough air is vented to reduce P by 0.1 bar. The vent line is so large that each drop in Pgj t is nearly instantaneous. Between each cycle the system is given time to reestablish equilibrium, as indicated by steady readings on the pressxue gauges and the position indicator. 

Thermodynamic systems make mechanical contact through the pressure that is exerted on the boundaries that separate them. At equilibrium, this pressure is equal on both sides of the boundary. If a pressure imbalance arises between the system and its surroundings, the boundaries of the system must move in response to the mechanical force. Such imbalance may arise from the application of a mechanical force that acts to compress or expand the system, or through the application of heat, which causes the volume to expand or contract. The movement of boundaries involves the exchange of work, which we call PFwork. 

FIGURE 11.9 Pressure imbalance The pain you feel in your ears upon climbing a moimtain or ascending in an airplane is caused by an imbalance of pressure between the cavities inside your ear and the outside air. 

The pain we feel in our ears when changing altitude is due to a pressure imbalance between the cavities within our ears and the ambient air. The greater number of molecular collisions on one side versus the other stresses the eardrum, resulting in pain. (Adapted from Human Information Processing An introduction to Psychoiogy, Second Edition, by Peter H. Lindsay and Donald A. Norman. Copyright 1977 Harcourt Brace Et Company.)... 

The charred material will create porosity, a weak area, and an electrically defective surface. Furthermore, the filling of the thick side ahead of the thin side creates a pressure imbalance generated by the 5 to 10 tons/sq. in. injection pressure that can cause the core to deflect toward the thin side, further aggravating the difference in wall thickness. This pressure imbalance will contribute to mold damage and make part production difficult if not impossible. We may conclude that the wall uniformity throughout the circumference must be within narrow limits, such as 0.002 in., whereas the thickness in general may vary from the specified value by 0.005 in. 

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