Vacuum system surging

W. E. Barr and V. J. Anhorn (1949) describe a merciuY cut-off with merciuY retium lines which prevent mercury surging into a vacuum system. 

The modified Full Cell treatment was employed for inpregna-ting the wood with monomeric materials. This treatment used the treating tank and the vacuum system as a surge tank system. A vacuum-tight glass reaction kettle was used as the treating... 

When a vacuum is used to outgas, precautions must be taken to prevent the initial surge from blowing powder throughout the system. In a well-sealed system outgassing can be taken as completed when no pressure increase can be detected after isolation from the pump. For routine work generally 10 to 10 torr (mm of mercury) is sufficient. The usual precautions, such as a baffle and a cold trap, should be taken to ensure no contamination by the pump oil. 

To get the best productivity out of a Q-ICP-MS instrument, this should have a stabilized power supply and be coupled to a flow injection (FI) system. The stabilized power supply ensures that the instrument is stable and protects the turbo-molecular vacuum pumps from power surges. The FI system allows samples to be diluted on-line, internal standards to be added, and AsH3 to be generated, this improving accuracy, precision, and laboratory productivity [41]. 

The pressure of the system was controlled to within 0.5 mm Hg for each series by a Cartesian diver manostat connected to a positive air leak, a vacuum pump, and a surge volume of 12 liters. An absolute mercury-in-glass manometer with a 0.1 mm sliding vernier was used to measure the pressure. Temperatures were monitored via two copper-constantan thermocouples one was located just above the liquid surface and the other just below it. Maximum differences of 0.4°C were detected, but an average of the two readings was reported to 0.2°C. Glacial acetic acid and acetone, both meeting ACS specifications, were used. 

The apparatus used in this study consisted of a vacuum chamber containing a spherical cryosurface and an independent gas addition system. The gas addition system, shown in Fig, 1, comprised a surge tank, a barometer for measuring the upstream gas pressure, and a series of five calibrated standard leaks, with individual valves, arranged in parallel, permitting individual use of each leak or any combination of leaks. The entire gas addition system has a separate pumping station. 

Fig. 20.9 A beer and yeast recovery system. 1. Fermenter 2. Beer clarifier 3. Surge tank 4. Yeast suspension tank 5. Filter aid mixer 6. Yeast (autolysis) tank 7. Rotary vacuum filter 8. Top feed applicator 9. Precoat applicator 10. Yeast suspension spray 11. Defoamer 12. Vacuum pump 13. Beer recovery tank 14. Pasteurizer 15. Yeast drier A. Wort preparation B. Beer treatment C. Dried yeast. (Based on drawing of Alfa-Laval Ltd.)...

Then, at about 9 00 a.m., as the surges have become so frequent as to be almost continuous, the vacuum plunges to 23 mm Hg. By 10 00 a.m., the surging has stopped and the vacuum at the jet suction has stabilized at a poor 25 mm Hg. Many, if not most, operators of large vacuum jet systems have observed this problem—but what causes it ... 

There are various types of switches. In a transmission system, a CB to interrupt current is the most common. For an ordinary switching surge calculation, the CB is modeled as an ideal switch controlled by time. When recovery and restriking transients are to be analyzed, the dynamic characteristics of a CB, especially for a vacuum CB or an interrupter, have to be considered. These characteristics are highly dependent on the material of the electrode and the CB s operation mechanism. 

Pressure Regulator—The regulator must maintain the pressure in the system essentially constant at all operating pressures. Automatic regulation can be achieved by a device that bleeds air into the pumping line near the pump on demand. A satisfactory device is a solenoid valve positioned between the vacuum source and a surge tank of at least 10-L capacity. Alternatively, a manual bleed valve can be maintained by a trained operator with a minimum of attention. 

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