U-shaped trap

The culprit turned out to be manure, all right, but of a decidedly human variety. The building s toilets connected to a septic tank, with the usual u-shaped trap built into the pipes. These traps are normally filled with water, which prevents any gas from backing up into the toilet bowl. Since septic tanks create the anaerobic conditions under which flammable methane can be generated, this is an essential safety measure. The toilets had not been used since the station was abandoned, and the water had evaporated from the plumbing system. Methane was now free to back up into the basement, and it had apparently done so. As the original investigator had proposed, a spark from the sump pump had probably set off the explosion. The bats had been falsely accused. 

Separation traps are typically a collection of interlinked U-shaped traps attached off the main vacuum line by two stopcocks (see Fig. 7.35). This arrangement allows separations of the mixed compound into as many traps as your system has. Once separation is complete, any fraction of the separation may be removed from the system at any time and in any order. The contents within a trap may even be sent back to the main holding trap for further separation. The following will provide a generalized procedure for utilizing such a separation process ... 

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. 

The primary oxidation products were passed through several layers of platinized asbestos and platinum wire formed into a star pattern. A series of experiments on the combustion of diphenyl sulphoxide showed that at 850°C and in the presence of a platinum catalyst sulphur is quantitatively converted into sulphur dioxide with no sulphur trioxide being produced. The oxidation temperature can be increased to 1200°C if a vanadium catalyst is used. The water is absorbed in a tube containing calcium sulphate, which helps to prevent the formation of sulphurous acid. Carbon dioxide and sulphur dioxide were concentrated in a U-shaped trap cooled with liquid nitrogen, and were subsequently analysed by GC at 92°C using a 6-m column filled with dinonyl phthalate. The content of sulphur in the sample was derived from the sulphur dioxide peak area with due regard to the weight of the sample and the calibration coefficient. 

A burner which utilises a mixture of fuel and oxidant gases and which is attached to a waste vessel (liquid trap) should be provided with a U-shaped connection between the trap and the burner chamber. The head of liquid in the connecting tube should be greater than the operating pressure of the burner if this is not achieved, mixtures of fuel and oxidant gas may be vented to the atmosphere and form an explosive mixture. The trap should be made of a material that will not shatter in the event of an explosive flash-back in the burner chamber. 

MacKinnon [91] and Wangersky [180] have made direct determinations of the volatile fractions from a variety of depths and stations in the North Atlantic. The volatile fraction as defined by MacKinnon s method is that fraction which can be removed from solution by purging with an inert gas at 80 °C and a pH of 8 for 10-12 hours, then at 65 °C for a further 10-12 hours. The inert gas stream is flushed through an ice-packed condenser to remove water, then into a trap packed with Tenax GC followed by a U-shaped stainless steel cold trap held at -78 °C. 

The apparatus consisted of a U-shape glass volatilization pipe preheated to a designed temperature, a nose-only exposure unit containing six mice, a glass wool trap (packed with 0.5 g of glass wool fiber) that sequestered the vaporized test compound, and a vacuum system that created negative pressure and pulled the air through the... 

To concentrate the acetylene and carbon dioxide resulting from the combustion of the sample, the gas flow was passed through a U-shaped glass trap cooled with liquid nitrogen. To avoid condensation of oxygen, the pressure in the trap was maintained at 110mm Hg. 

A trap for the unwary is not to investigate fully the cause of the U-shaped non-linear free energy relationship. Young and Jencks [105c] studied the reaction of hydroxide with acetophenone bisulphites (Eqn. 124)... 

C, respectively). These arsines, when formed in a reaction vessel, were trapped in a U-shaped tube immersed in liquid nitrogen. The liquid nitrogen was then removed and the tube warmed up for sequential evaporation, separation and detection of the arsines. At pH > 6, only the more toxic trivalent As species could be transformed into their arsines without interference from the pentavalent species (Andreae 1977, Norin and Vahter 1981). Avoiding the liquid nitrogen trap, the separation was also performed by ion-exchange chromatography (Tam et al. 1978). Since arsenobetaine is not transformed into a volatile hydride, these procedures allowed easy differentiation between toxic and practically... 

Tub trap- Curved, "U" shaped section of a bath tub drain pipe that holds a water seal to prevent sewer gasses from entering the home through tubs water drain. 

The boiling flask is charged with 2-acetoxycyclohexanone and heated to reflux. The pyrolysis column, which is packed with glass beads and electrically heated to 500 with the Nichrome wire, cracks a portion of the ester then the cyclohexenone, acetic acid, and unreacted acetate pass into the fractionating column. The products are collected by distillation and the unreacted acetate is continuously returned to the boiling flask through the pyrolysis column bypass. The vapor trap, which is merely a U-shaped portion of the bypass for the pyrolysis column, soon fills with liquid and prevents distillation around the pyrolysis chamber. The yield of 2-cyclohexenone with this apparatus exceeds 90%. 

Fig. 9.26 Joffe trap (a) with Z-shaped electric wire, (b) with U-shaped wire with the corresponding magnetic field...

Fig. 6 Using U-shaped microfluidic structures, two different cell types (shown in red and green) can be paired up side by side in a single trapping site using fluid flow. A large array of cell pairs can be created within a single microfluidic device for high-throughput analysis of cell-cell interactions (Reprinted from [14] by permission from Macmillan Publishers Ltd Nature Methods, copyright (2009))...

FIGURE 5.6. A trapped conformation for the algorithm with only local moves for a chain on the simple square lattice (A). A longer distance move that guarantees the ergodicity of the algorithm, where a U shaped fragment at one part of the chain is cut-off and attached somewhere else (B). 

Another form of redundancy is the excess capacity often built into plants with more than one processing line. If two sets of drying towers are used, for example, the capacity of each may be more than 50% of the plant design capacity. The primary justification for multiple trains usually is to enhance turndown capability or to allow continued operation even when one train must be shut down. The same approach may be taken with the cooling section. Given the sizes of chlorine gas headers, valves would be expensive and probably ineffective as shutoff devices. Many plants therefore use U- or J-shaped traps in the piping. These can be filled with water or acid to stop the gas flow and to isolate equipment for maintenance. 

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