Siphoning action

Pressurized Siphon Basket Centrifuges In addition to a siphoning action downstream of the filter, an additional pressure difference of as much as 5 to 6 atm is imposed across the filter to further... 

Proper vessel designs should avoid discharges from high-positioned coolers directed down a pipe. This situation reduces pressure in coolers via siphon action. 

The values of friction loss (including entrance, exit losses, pressure drop through heat exchangers, control valves and the like) are hjL and h L. The total static head is D — Sl, or [(D -f D ) — (—Sl)] if siphon action is ignored, and [(D + D ) — (S l)] for worst case, good design practice. 

Figure 3.6 Lipids are extracted from some biological materials with a soxhelet extractor (above). The solvent is vaporized in the distillation flask by the heating mantle, rises through one of the exterior tubes to the condenser, and is cooled to form a liquid. The liquid drops onto the porous thimble containing the sample. Siphon action periodically drains the solvent back into the distillation flask. The extracted lipid collects as a solution in the solvent in the flask. 

Before the acid truck was unloaded, acid started to overflow and pour through the six-inch (15 cm) line into the scrubber. The alert truck driver quickly responded. He abruptly shut the delivery valve on his truck. Unexpectedly, the partial vacuum created by the siphoning action of the overflowing liquid, exceeded the tank s vacuum rating and the storage tank was totally destroyed (see Figures 2—7, 2—8, and 2—9). [2]... 

The flushing action of the toilet commences when the bowl is filled from a reservoir until the water level tops the inverted-U-shaped trap and starts to spill over the other side. Once water starts to flow over the side of the trap, it pulls the rest of the water with it, as a chain would pull the links that are attached to it down to a lower level. With water, intermolecular attractions form the chain that pulls the water molecules one after another. This siphoning action has to initiate quickly so that water will surge over the trap and make a moving seal. 

When the mobile phase washes over the sample spot and starts on down the paper, it will begin to siphon when its level gets below the solvent level in the solvent tank. This will cause the solvent to move too fast for the desired separation equilibrium to be attained, and streaking will occur. If a small-diameter rod is placed so the entire width of the paper makes contact with it, then a considerable adsorption force is developed between the solvent and the rod. This is sufficient to stop the siphoning action, and the solvent moves down the paper by capillary action alone. 

When an upward loop is not vented (Fig. 5.16, c, e with a closed vent valve or no vent line), inerts may accumulate at the high point, causing intermittent siphon action and reflux flow oscillation. Cases were reported (68) where hot vapor was sucked back from the column into the high point and caused hammering upon contacting the subcooled reflux. This ruptured the reflux line and nozzle. The phenomenon is most troublesome in vacuum, where slight air leaks occur. 

A practical system for analytical scale high-resolution separations was first demonstrated by Culbertson and Jorgenson. Narrow diameter capillaries and LIF detection were used to resolve analytes with extremely small differences in mobility such as peptide isomers. Misleveling of the buffer reservoirs, using a siphoning action to provide a counter flow in large diameter capillaries, was also reported with modest resolution improvements. ... 

The increased capacity of peeler centrifuges has been obtained by the use of a siphonic action to enhance the effective pressure differentials, as shown in Figure 58.18. Here the filtrate is not centrifuged through the drum perforations immediately after penetrating the filter cake, as occurs in standard peeler centrifuges, but collects behind the filter cloth. This chamber is connected to a ring cup that behaves... 

FIGURE 58.19 Mechanism of siphonic action (a) standard centrifuge, (b) negative siphon, (c) positive siphon (1, basket 2, medium 3, hole 4, filtrate chamber 5, siphon chamber 6, partition plate 7, siphon pipe 8, filtrate 9, cake). (From Mitsubishi Kakoki Kaisha, Ltd., Catalog 7-1-1 02-01B-P. With permission.)... 

In a variation called descending paper chromatography [Fig. 2-34(b)], the solvent tray is placed at the top of the jar and the solvent is allowed to move down the strip of paper. The flow of solvent is much more rapid in this case since it is aided by gravity. By having the paper rise out of the tray slightly before descending, a too rapid siphoning action is avoided. 

Increased capacity of peeler centrifuges has also been obtained by use of a siphonic action to enhance the efrbctive pressure dififerentials, as shown in Figure 8.31. 

Robert Boyle suggested that siphon action may be used to fill the flask by itself. Is this possible Why or why not ... 

Siphoning action of pool water is prevented by holes drilled in the pump suction line 18 inches below the normal pool water level. These syphon-breaking holes are also used to air bind the pump during operations when components or piping associated with the primary system must be replaced or repaired. The holes drilled in the bottom five feet of the return piping act as a diffusing system to mix cooled return water with bulk pool water. 

Figure 5.6. The Blyth elutriator uses a siphon action to cause the suspension to flow through the elutriation chambers.

Amounts of mercury less than 50 mg—Invert the receiver, and fix it in the neck of a flask by means of a cork that has a second hole through which a glass tube passes so that suction may be applied. Wash with acetone until free from tarry matter. (Slight suction is necessary to draw liquid through at first it then percolates through by siphon action.) Wash the receiver thoroughly with water to remove acetone. 

Another important point for gravity return reflux is the method of connecting the reflux piping to the column. Each of the two piping arrangements of Figure 3.24 has an undesirable upward loop just before entry into the column. Inerts sometimes accumulate in this pocket, thereby causing a reflux flow oscillation as a result of an intermittent siphon action. There have been cases where hot vapor was sucked back into this pocket and caused such severe hammer that the reflux line and column nozzle were ruptured. 

Mitisation from the consequences of accidents Siphone-Brake valve in the pool water level sustaining system Anti-Siphon Action Minimum water level to cover the reactor core for LOCA type of events not maintained to avoid core damage... 

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