Evacuation pumps, mechanical

Friction losses, air steam, 131 Pressure losses chart, 134 Vacuum pumps, mechanical, 382 Liquid ring pumps, 383-385 Liquid ring volume displaced/ evacuation, 387... 

A solution of 30 g (0.1 mole) of 17j5-hydroxy-5a-androstan-3-one (androstano-lone), 20 ml of pyrrolidine and 200 ml of benzene is heated at reflux temperature for 2.5 hr under a Bidwell-Sterling water trap. The benzene solution is evaporated to dryness in a rotating evaporator connected to a water aspirator. The white cake which remains is broken up and dried further by immersing the flask in a water bath at 60-75° and evacuating the flask with a mechanical vacuum pump. After 0.5 hr the solid cake is broken up again and dried for another 0.5 hr at 60-75°. The enamine (9) obtained should smell only faintly of pyrrolidine. 

Mechanical separations, 224 Mechanical vacuum systems, 342 Applications, 352, 353 Barometric iniercondenser, 349 Evacuation times, 387 Operating range, 355 Performance curves, 386 Pump down, 380... 

One gram of silver 0-alumina crystals is placed in a Vycor tube with a 1-cm id and 20 cm long and closed at one end. Three grams of gallium and 4 g of iodine are added, and the Vycor tube is necked down near the middle in preparation for sealing off. The tube is evacuated with a mechanical pump to <1 torr pressure and sealed. The sealed tube is placed in a cold furnace and then heated to... 

The reactor is evacuated with a two-or three-stage oil or mercury diffusion pump, backed by a rotary mechanical pump. A large removable liquid-nitrogen-... 

The liquid can be exploded by a detonator, though not by mechanical shock [1]. Use of propylene oxide as a biological sterilant is hazardous because of ready formation of explosive mixtures with air (2.8—37%). Commercially available mixtures with carbon dioxide, though non-explosive, may be asphyxiant and vesicant [1], Such mixtures may be ineffective, but neat propylene oxide vapour may be used safely, provided that it is removed by evacuation using a water-jet pump [2]. The main factors involved in the use and safe handling on a laboratory scale have been discussed [3]. The energy of decomposition (in range 340—500°C) has been measured as 1.114 kJ/g [4]. 

The oxidation process was carried out in a home-made, vacuum furnace which included a quartz container included in a furnace. The quartz container was evacuated with a high-vacuum system composed to diffusion pump and a mechanical pump. The system was connected to a sensitive manometric manifold to measure the pressure of the oxidant gas [39],... 

To demonstrate the value of this system, suppose you have a mechanical pump who s general lower range is 2 torr (in an acceptable pumping time period ). By the third evacuation and purging, the amount of residual air is 2 x (2/760)2, or about 10 5 torr.23... 

Let the mechanical pumps evacuate the traps before they are placed in liquid nitrogen to prevent freezing oxygen within the traps. 

Low pressures can be achieved in a mechanical or "roughing" pump, by using a fluid (water, mercury, oil) in a rotating-vane technique to adsorb molecules within the fluid when exposed to the container to be evacuated, then expelling these molecules to the laboratory when the vane has brought the fluid into contact with laboratory air. 

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