Vacuum corrections, pressure

The high water vapor pressure was thus limiting vacuum. Correct. 

Pressure and Vacuum. Pressure is usually designated as gauge pressure, absolute pressure, or, if below ambient, vacuum. Pressures are expressed in pascals with appropriate prefixes. When the term vacuum is used, it should be made clear whether negative gauge pressure or absolute pressure is meant. The correct way to express pressure readings is "at a gauge pressure of 13 kPa" or "at an absolute pressure of 13 kPa."... 

Benzoxazolinone [59-49-4] M 135.1, m 137-139 , 142-143 (corrected), b 121-213 /17mm, 335-337 /760mni. It can be purified by recrystn from aqueous Me2CO then by distn at atm pressure then in a vacuum. The methyl mercury salt recryst from aq EtOH has m 156-158°. [J Am Chem Soc 67 905 1945.]... 

The best way to prevent accidents such as this is to use rupture discs, which are harder to assemble incorrectly and which can be checked for correct installation after assembly. It is possible to get discs permanently attached to their vacuum supports by the manufacturer and fitted with a projecting tag, which carries the words vent side on one side. The tag also gives the pressure rating. 

Example 3-6 NPSH Available in Vacuum System, 191 Example 3-7 NPSH. Available in Pressure System, 191 Example 3-8 Closed System Steam Surface Condenser NPSH Requirements, 191 Example 3-9 Process Vacuum System, 192 Reductions in NPSHr, 192 Example 3-10 Corrections to NPSHr for Hot Liquid Hydrocarbons and Water. 192 Example 3-9 Process Vacuum System, 192 Example 3-10 Corrections to NPSHr for Hot Liquid Hydrocarbons and Water, 192 Example 3-11 Alternate to Example 3-10, 194 Specific Speed,... 

Two heat-sensitive organic liquids of an average molecular mass of 155 kg/kmol are to be separated by vacuum distillation in a 100 mm diameter column packed with 6 mm stoneware Raschig rings. The number of theoretical plates required is 16 and it has been found that the HETP is 150 mm. If the product rate is 5 g/s at a reflux ratio of 8, calculate the pressure in the condenser so that the temperature in the still does not exceed 395 K (equivalent to a pressure of 8 kN/m2). It may be assumed that a = 800 m2/m3, /x = 0.02 mN s/m2, e = 0.72 and that the temperature changes and the correction for liquid flow may be neglected. 

The ethylmagnesium bromide is prepared in dry tetrahydrofuran and stored no longer than 1 week in a 250-ml. tube fitted with a 3-way vacuum stopcock and a dropping buret. The solution is decanted into the buret, and the correct volume is transferred to the reaction flask with positive nitrogen pressure. The tetrahydrofuran is purified by distillation from lithium aluminium hydride. See Org. Syn., 46, 105 (1966), for warning regarding the purification of tetrahydrofuran. 

Hydrogen isotherms at 77 K and up to 4 MPa were carried out in a DMT high-pressure microbalance. The sample was degassed at 423 K during 4 hours under vacuum. Sample weight was between 250 to 750 mg. The experimental results were corrected for buoyancy effects related to the displacement of gas by the sample, sample holder and pan21. 

The different modes of injection, i.e., gravity injection, pressure or vacuum injection, and electrokinetic injection, are addressed. Also, several practical experimental issues are described, such as correct treatment of electrolyte solutions and the importance of a rigorous capillary rinsing procedure. 

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