Vacuum connection

Objective of the microscope 2. sample 3. sample support 4. electrical heating 5. cooling chamber with LN-. connection 6. vacuum connection (Fig. 1 from 11.271). 

Drying tunnel in A 2, valve before the condenser 3, lift- and transport device 4, trays in transport position 5, trays on the shelves during drying 6, heated shelves in B 7, radiation plates 8, trays 9, guide rails for the tray transport 10, separation plate between tunnel and condenser 11, condenser 12, vacuum connection. 

Fig. 6.4. Cross-section of a metal diffusion pump. The upper stage in this pump has a wide annular opening (A) which provides a good ultimate vacuum. The lower stage has a small annular opening (A ) so the pump will operate against a high fore pressure. (B) High-vacuum connection to the low-temperature trap and vacuum line. (C) Connection to rotary oil-sealed pump. This pump is cooled by means of water tubes (D). Air-cooled versions have fins in place of these tubes and a fan is installed to blow air over these fins. (E) Electrically heated oil reservoir.

A test leak (shown below) consists of a quartz diffusion barrier of length 70 mm, internal diameter (wall thickness (d) 1 mm. If the reservoir contains 400 mbar He and discharges into a vacuum via the vacuum connection flange, calculate the leakage at 20 °C (/cperm quartz glass = 5 x 10-5 mbar L s"1 mm m-2 bar). 

Fig. 26. Stone filter funnel for strongly acid precipitates (1) vacuum connection (2) discharge line for removing filtrate (3) air outlet (4) connection to wash water, or to the sewer for emptying.

Figure 6.8-2 IR cell for liquids and solids to record spectra in the temperature range -180 °C to -1-2.50 °C. 1) Contact for thermocouple 2) Vacuum connection 3) Connection for the window heating 4) Flow through tube 5) attenuation assembly for the cooling performance.

The S3N2CI2 is prepared according to Part A. After the volatile impurities have been removed, dry air is allowed to enter the air condenser. The bottom of the condenser is then connected to a 150-ml. round-bottomed three-necked flask fitted with an inlet tube for chlorine and a vacuum connection (Fig. 6). The vacuum connection on top of the air condenser is replaced with a drying tube containing anhydrous calcium sulfate. The assembly is placed in a hood the inlet tube is connected to a chlorine cylinder, and a slow stream of chlorine is passed through the air condenser over the S3N2CI2. Soon after the start of the chlorine flow, the S3N2CI2 turns into a dark red-brown slurry, which falls... 

The stopper is cut off the lower leg of the Dean-Stark trap, leaving the tube with an opening of about 5 to 6 mm. To the end of this tube is connected a suction flask F by means of a short rubber tube. Flow through the tube is controlled by means of a pinch clamp E. A vacuum connection is made through trap K, which is cooled by an ice-salt mixture. The pressure in the system is determined by means of the mercury-filled manometer J. 

A manual microfiltration apparatus (Fig. 3) has been made by the present authors for use with a CRC thimble. The apparatus is constructed of stainless steel with neoprene rubber seals. A hollow base holds a test tube for collection of the filtrate, if required, and has a connection for a vacuum pump. The top, which fits onto the base with an O ring, has on its upper surface a well to hold the CRC thimble and a support for the removable filter cover. The cover has a probe that is inserted into the solution to be filtered. When negative pressure is applied to the vacuum connection and the CRC thimble is held in place by the filter cover, the airtight seals enable solution to pass through the probe. 

Fig. 3. Microfiltration apparatus. 1, Stainless steel base 2, Stainless steel top 3, neoprene rubber seal 4, vacuum connection 5, CRC thimble 6, test tube for collection of filtrate 7, airtight filter cover with probe 8, airtight seating.

FIG. 10.5. (a) A glass moisture trap containing a boat for phosphoms pentoxide. (b) A metal moisture trap in section, showing the trays for phosphoms pentoxide. (c) Oil reservoir, fitted to tlie vacuum connection on a rotary oil pump. Tlie two-way stopcock is opened to tlie atmosphere when the pump is stopped. 

Sublimation is a technique that is much easier to carry out on a small sccile than on a large one. It would be unusual for a research chemist to sublime more than about 10 g of material, because the sublimate tends to fall back to the bottom of the apparatus. In an apparatus such as that illustrated in Fig. 14(a), the solid to be sublimed is placed in the lower flask and connected via a lubricant-free rubber 0-ring to the condenser, which in turn is connected to a vacuum pump. The lower flask is immersed in an oil bath at the appropriate temperature and the product sublimed and condensed onto the cool walls of the condenser. The parts of the apparatus are gently sepcu ated and the condenser inverted the vacuum connection serves as a convenient funnel for product removal. For large-scale work the sublimator of Fig. 14(b) is used. The inner well is filled with a coolant (ice or dry ice). The sublimate clings to this cool surface, from which it can be removed by scraping and dissolving in an appropriate solvent. 

Preliminary filtration tests may be made with a Buchner funnel or a small filter leaf, covered with canvas or other appropriate medium and connected to a vacuum system. Usually the suspension is poured carefully into the vacuum-connected funnel, whereas the leaf is immersed... 

A three-cell apparatus (Vogel 724S) was used in electro-ultrafiltration [22]. The middle cell containing the material suspension had a stirrer and a water inflow. Each side of the middle cell was provided with a micropore filter attached to the platinum electrodes that separated the middle cell from the two outside chambers. These chambers had vacuum connections. Therefore, the ions accumulating at the respective electrodes were washed away by the continuous stream of the solution from the suspension in the middle cell to the eluate in the collecting tanks combined with the side chambers. A steady disequilibrium between the P on the materials and the respective soluble form in solution occurred and the materials were forced to replenish the P displaced away with the eluate. The concentration of P in the eluates was measured by UV-VIS spectrophotometry as phosphomolybdate [23]. 

A = Flask for liquid with thermometer, B = Ground joint with hook for thermometer, C = Vacuum connection,... 

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