Water jet pumps

Mount the upper end piece of the filling tube and immediately connect it to the pump, open the column outlet, and start the pump at a flow rate of 10 ml/min (delivering water or any desired buffer system of low ionic strength). Optionally, the column outlet can be additionally connected to a water jet pump, which has to be operated during the first 2 min of packing. The water... 

After cooling, unreacted ethylenediamine is neutralized in a cooling mixture with the absolute ethanolic hydrochloric acid, filtered off from any components that are insoluble in ethanol and approximately two-thirds of the solvent filtered off under suction in a water jet pump vacuum. Residual quantities of ethylenediamine dihydrochloride are precipitated in fractions by the careful addition of ethyl methyl ketone, after which the imidazoline hydrochloride is separated off by the addition of dry ether. Following repeated recrystallization from ethanol ether, 2-[0(-(2,6-dichlorophenoxy)ethyl] -A -imidazoline hydrochloride is obtained in the form of small white crystals melting at 221°C to 223°C. 

Following variant II, after treating by the modifier, the solid phase was separated by filtration and additionally washed off with 0.2 liters of water under vacuum of the water-jet pump. Further, as in variant I, one part of the product was dried at 105°C for two hours (product C), while the other was dried at 20°C until a sample mass became constant (product D). The products were investigated by the powder X-ray phase analysis (PXRD) using nickel-filtered CoKa radiation. 

Prior to functionalization the carbon nanomaterials were washed in concentrated nitric acid (65% Fisher Scientific) for 8 h using a Soxhlet device in order to remove catalyst residues of the nanomaterial synthesis as well as to create anchor sites (surface oxides) for the Co on the surface of the nanomaterials. After acid treatment the feedstock was treated overnight with a sodium hydrogen carbonate solution (Gruessing) for neutralization reasons. For the functionalization of the support media with cobalt particles, a wet impregnation technique was applied. For this purpose 10 g of the respective nanomaterial and 10 g of cobalt(II)-nitrate hexahydrate (Co(N03)2-6 H20, Fluka) were suspended in ethanol (11) and stirred for 24 h. Thereafter, the suspension was filtered via a water jet pump and finally entirely dried using a high-vacuum pump (5 mbar). 

It is desirable to provide the Woulf bottle or filter flask, which should be connected to every water-jet pump, with a regulating cock which not only enables the suction to be cut off conveniently but also allows of changes in the partial vacuum, which are necessary in many cases. 

New tubing is artificially aged by heating in the drying oven at 100-110° (not higher ) drawing air through at the same time for one hour by means of a water jet pump. 

Avoidance or ban of unsafe techniques in the laboratory, e.g., oral suction of chemicals in pipettes, sucking of halogenated compounds with a water-jet pump because of effluent contamination. 

Included in the class of fluid-entrainment pumps are not only pumps that use a fast-streaming vapor as the pump fluid, but also liquid jet pumps. The simplest and cheapest vacuum pumps are water jet pumps. As in a vapor pump (see Fig. 2.46 or 2.51), the liquid stream is first released from a nozzle and then, because of turbulence, mixes with the pumped gas in the mixing chamber. Finally, the movement of the water - gas mixture is slowed down in a Venturi tube. The ultimate total pressure in a container that is pumped by a water jet pump is determined by the vapor pressure of the water and, for example, at a water temperature of 15 °C amounts te about 17 mbar. 

OB to C02 —37.4% colorless, somewhat volatile liquid, with faint aromatic odor sp gr 1.348 at 20/4°, fr p below —20°, bp 91—2° in a vacuum of a water jet pump and decomp at atm pressure miscible with w and sol in ale, eth chlf dissolves in coned sulfuric acid with considerable evolution of beat, so that in the detn of die nitrogen concent by Nitrometer Method (See Vol 1 of Encycl, pp A373—A378)... 

Buchner funnel along a glass rod, then close the clamp and switch on the water-jet pump. When the major part of the liquid has been filtered and the precipitate has become compact, see that there are no cracks in it. If cracks form on the surface of the precipitate, carefully smooth them out with a glass rod or the wide part of a glass stopper. 

For the more complete separation of the filtrate from the precipitate, press the latter slightly against the funnel bottom with a glass stopper. Filtration is considered to be complete if filtrate drops no longer appear at the tip of the funnel. Prior to closing the cock of the water-jet pump, extinguish the vacuum in the suction flask. To do this, open the safety clamp on the outlet tube or extract the stopper with the funnel from the suction flask. 

Crucibles No. 1 and 2 are used for separating coarse-grain precipitates, and No. 3 and 4 for separating fine-grain ones. Sintered glass funnels and crucibles are put instead of a Buchner funnel into a suction flask with connection to a water-jet pump. 

A vacuum desiccator has a side arm with a cock by means of which it is connected via a protective wash bottle to a water-jet pump producing a vacuum in the desiccator. 

It is often required in laboratory practice that the space in an apparatus should contain no air and other gases. Such a rarefied space is called a vacuum. Water-jet pumps produce a rarefaction of the... 

Water-jet pumps can be used wherever there is an adequate pressure of the water in the mains 2 at or 196.2 kPa). The ultimate vacuum depends both on the design of the pump and the water temperature and cannot exceed the water vapour pressure at the given temperature (Appendix 1, Table 13). 

Lower several pieces of copper shavings into three-neck flask 1, and carefully switch on water-jet pump 8. When the entire apparatus is filled with nitrogen oxides, heat the part of the tube where the selenium is with the flame of a gas burner. First heat carefully, and then more strongly. What occurs ... 

When the reaction terminates (how can you determine this ), cool the apparatus in a stream of ammonia. Disconnect the two-neck bottle and use a water-jet pump to remove the ammonia from the apparatus. Extract the boat and put it into a weighing bottle for boats or into a test tube closed with a stopper. Weigh it. Determine the yield of magnesium nitride. 

Preparation of Nitric Acid by Oxidizing Ammonia. Assemble an apparatus as shown in Fig. 90. Pour a 2% ammonia solution into flask 1. Put a loose layer of freshly roasted platinized asbestos into the middle of tube 2 over a length of 4-5 cm. Pour a neutral litmus solution or several drops of methyl red into flask 3 and connect the short tube of this flask to water-jet pump 4. Heat the platinized asbestos slightly with the flame of a gas burner and pass through it... 

After 10-12 hours, decant the solution from the unreacted copper shavings into vessel 1 (Fig. 92fe). Connect the vessel via trap 2 and empty wash bottle 5 to a water-jet pump. Open clamps 4 and 5,... 

When no liquid remains in vessel 7, close clamp 4, open clamp 5, close the cock of the water-jet pump, and disconnect vessel 1. In a dry chamber, extract the powdered anhydrous copper nitrate from the vessel and put it into a weighed weighing bottle. Calculate the yield in per cent. 

Replace the stopper and switch on the water-jet pump (very slow operation). When the entire phosphorus has reacted, disconnect the pump and dissolve the phosphorous anhydride gathered in tube 4 and U-tubes 5 and 6 in 10-20 ml of distilled water. Filter the solution through a paper filter and keep it for further experiments. 

Assemble an apparatus as shown in Fig. 95. Thoroughly dry all parts of the apparatus prior to the experiment. What should the calcium chloride tube be filled with Connect the wash bottle (or a U-tube) to the water-jet pump. Put red phosphorus into a spoon... 

Preparation of Sodium Peroxide. Assemble the arrangement shown in Fig. 117. Pour a little vaseline oil into wash bottle 1 and leave bottle 2 empty. Put 2-3 g of cleaned metallic sodium into porcelain boat 3 and place it into quartz or refractory glass tube 4. Cover the tube with asbestos and switch on the water-jet pump connected to the arrangement (ZrasZaZZ protective bottles ahead of the pump . Heat the part of the tube where the boat with the sodium is with a gas burner flame. When the sodium ignites, reduce the heating. Suck... 

Rapidly pour over the solution into a round-bottomed flask and close it with dark paper (the solution turns yellow in the light). Connect the flask to a water-jet pump via an empty trap and drying columns with a granulated alkali (see Fig. 1196, p. 196). 

After 24 hours, distil off the excess nitrogen(II) oxide and acetonitrile on a water bath in a vacuum produced by a water-jet pump. Weigh the product and calculate its yield in per cent. 

Fill dropping funnel 8 with a solution of 75 g of sodium acetate in 100 ml of water. Fill the apparatus with dry nitrogen from gas meter 2, opening clamps 9 and 10 and closing the clamp on the rubber tube connecting flask 15 to a water-jet pump. Make sure that the nitrogen passes through wash bottles 27 and 18 filled with vaseline oil. 

Separate the solution from the unreacted metal by decantation. Transfer the solution into a wide test tube (see Fig. 118). Distil off the ethanol in a vacuum produced by a water-jet pump while carefully heating the test tube in a beaker with boiling water. What crystallizes in the tube ... 

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