Mechanical pumps condensate trap

If the pump is a filter pump off a high-pressure water supply, its performance will be limited by the temperature of the water because the vapour pressure of water at 10°, 15°, 20° and 25° is 9.2, 12.8, 17.5 and 23.8 mm Hg respectively. The pressure can be measured with an ordinary manometer. For vacuums in the range lO" mm Hg to 10 mm Hg, rotary mechanical pumps (oil pumps) are used and the pressure can be measured with a Vacustat McLeod type gauge. If still higher vacuums are required, for example for high vacuum sublimations, a mercury diffusion pump is suitable. Such a pump can provide a vacuum up to 10" mm Hg. For better efficiencies, the pump can be backed up by a mechanical pump. In all cases, the mercury pump is connected to the distillation apparatus through several traps to remove mercury vapours. These traps may operate by chemical action, for example the use of sodium hydroxide pellets to react with acids, or by condensation, in which case empty tubes cooled in solid carbon dioxide-ethanol or liquid nitrogen (contained in wide-mouthed Dewar flasks) are used. 

Extraction Frozen krill (85 g) is briefly homogenized with 60% ethanol (220 ml) at about 0°C, and centrifuged. The supernatant is rapidly concentrated under reduced pressure in a 2-liter flask at about 40°C (using a rotary evaporator, a mechanical vacuum pump, and a large condensate trap immersed in dry ice/acetone) to a volume of 15-20 ml. After the addition of 30 ml of cold ethanol, the solution is temporarily stored at —30°C. Materials similarly prepared from 6 batches (510 g krill in total) are combined, centrifuged, and the supernatant is concentrated to 30 ml, and then mixed with 70 ml of ethanol. Compound F in the solution is extracted with 120 ml of n-butanol. 

All exhaust from a mechanical pump should be vented to a fume hood regardless of the room s ventilation quality or the type of pumped gases. Each time you bring new samples into vacuum conditions, your system is pumping at atmospheric pressured Because pump oils have low vapor pressures, and pump oils themselves are considered nontoxic, there is little concern for breathing pump oil mist. However, there may be dangers from trapped vapors within the pump oils. Regardless, there is little reason to breathe the pump oil mist if it can be avoided. Check with the manufacturer or distributor of your pump for an oil mist filter for your pump. If you use a condensate trap, be sure you position your exhaust line so that material does not drain back into the pump (see Fig. 7.14). 

Fig. 7.14 The proper orientation of a mechanical pump s exhaust condensate trap. Reprinted from N.S. Harris, Practical Aspects of Constructing, Operating and Maintaining Rotary Vane and Diffusion-Pumped Systems, Vacuum, Vol. 31, 1981, p. 176, with kind permission from Elsevier Science Ltd, The Boulevard, Langford Lane, Kidlington 0X5 1GB, UK.

To prevent (or limit) condensable vapors from getting to a pump, traps [either of chilled or chemical design (see Sec. 7.4 on traps and foreline traps)], are used. Depending on the type of trap used, there are opportunities for vapors to pass on to the mechanical pump. Thus, one cannot depend fully on traps of any kind, and one must also deal with vapors at the pump itself. 

The movement of condensable vapors from the mechanical pump can potentially decrease diffusion pump performance. If your system has diffusion and mechanical pumps, there should be a trap between the two pumps in addition to the cold trap between the system and the diffusion pump (see Fig. 7.30). The use of properly designed and placed cold traps can allow diffusion-pumped vacuum systems to achieve vacuums in the region of 10 9 torr35 and greater ... 

Liquid-nitrogen cold traps stop condensable vapors from traveling between mechanical pumps, diffusion pumps, and the rest of the system. They also protect the helium leak detector from possibly contaminating materials (such as silicon-based diffusion pump oil). 

The performic acid is prepared in the usual manner by allowing a mixture of 1.0 ml of 30% (w/v) H2O2 and 9.0 ml of 88% (w/v) formic acid to stand at room temperature for 1 hr, after which it is cooled to 0°C. A known amount of protein, usually the amount used for routine hydrolysates, is dissolved in 1 to 2 ml of the reagent in a cooled hydrolysis tube. If the protein does not dissolve readily in the cold reagent, it can usually be dissolved first in 0.1 ml of 100% formic acid at room temperature. The mixture is kept at 0°C for 4 hr after which performic acid is destroyed by the addition of 0.15 ml of cold 48 % (w/v) HBr per ml of performic acid reagent used. The bromine which forms, as well as the formic acid solution, can best be removed from the hydrolysis tube by rotary evaporation under high vacuum (mechanical pump) at 40°C with NaOH pellets in the condenser trap the condenser should be cooled with dry ice in ethanol. Acid hydrolysis of the oxidized sample and analysis of the resulting hydrolysates are performed in the usual manner ( 2.1.2). 

Many evaporator calandrias condense steam at subatmospheric pressures. Consequently, condensate must be removed by pumping, either with mechanical pumps or pumping steam traps. Large condensate loads are usually best handled when liquid levels are controlled and condensate removed with the appropriate method. 

Apparatus 1-1 flask with a dropping funnel, a gas-tight mechanical stirrer and a very efficient reflux condenser the top of the condenser was connected with a trap. A tube containing anhydrous CaCl2 was placed between the trap and the water pump. The connection of the trap was made in such a way that the cumulene vapour could enter the large annular space (the long inner tube being connected to the water pump). 

A. 2-(Trimethtjlsiloxymethyl)allyltvimethylBilane. An oven-dried (Note 1) 2-L, three-necked, round-bottomed flask is equipped with an air-tight mechanical stirrer (Note 2), a 500-mL pressure-equalizing dropping funnel (Note 3), and a reflux condenser. The top of the condenser is connected to a three-way stopcock with one branch connected to a nitrogen source and the other to a variable pressure oil pump with a dry-ice trap (Note 4). The apparatus is flamed dry under a steady stream of nitrogen. The flask is... 

The condensate return (returned, condensate or simply condensate) tank is positioned at the lowest point in a condensate return (CR) system and collects condensate from the various steam heating and process applications. If traps or condensate pumps are installed to aid the return of the condensate (as is usually the case), this is called a mechanical CR system. Nevertheless, some parts of the system may return condensate by gravity either to a condensate tank or directly to a FW tank. 

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