Pressure and Vacuum Systems

Lower pressure drop for vacuum systems Allows for better low pressure and vacuum system operation and lower bottoms temperature, with less degradation of bottoms product. 

Discuss the potential hazards associated with the operation of pressure and vacuum systems, and the special safety precautions required. 

Types of Systems Generally, pneumatic conveyors are classified according to five basic types pressure, vacuum, combination pressure and vacuum, fluidizing, and the blow tank. 

Another example of pressure control by variable heat transfer coefficient is a vacuum condenser. The vacuum system pulls the inerts out through a vent. The control valve between the condenser and vacuum system varies the amount of inerts leaving the condenser. If the pressure gets too high, the control valve opens to pull out more inerts and produce a smaller tube area blanketed by inerts. Since relatively stagnant inerts have poorer heat transfer than condensing vapors, additional inerts... 

The importance of the first three of these factors has already been discussed. The temperature factor would include the cost of insulation plus the increase in metal thickness necessary to counteract the poorer structural properties of metals at high temperatures. Zevnik and Buchanan17 have developed curves to obtain the average cost of a unit operation for a given fluid process. They base their method on the production capacity and the calculation of a complexify factor. The complexity factor is based on the maximum temperature (or minimum temperature if the process is a cryogenic one), the maximum pressure (or minimum pressure for vacuum systems) and the material of construction. It is calculated from Equation 2 ... 

All these plants are of the chamber type (see Fig. 1.88 (c)) with cooled and heated shelves and a condenser which can be separated from the drying chamber by a valve. Refrigeration and vacuum systems should be laid out for temperatures and pressures which can be expected under extreme experimental conditions, even if these extreme data may not be used in the production process. Pilot plants for pharmaceutical or medical products should be laid out differently than those used for food. 

Beaded pipe is used for process waste lines and vent lines. Some applications have also been made in low-pressure and vacuum lines. Beaded end pipe is available in nominal diameters of VA through 6 in. For operating conditions manufacturers should be consulted. In this system the ends of the pipe and fittings are formed into a bead, as... 

C. Stopcocks for Pressure and Vacuum. In a typical Schlenk system, the apparatus is repeatedly exposed to a small positive pressure and to vacuum. This causes stopcocks to become dislodged therefore, satisfactory performance requires good stopcock retainers. An excellent retainer design is illustrated in Fig. 8.8. This particular retainer requires the use of the stopcock produced by the same manufacturer.6... 

Gas Sources and Attainable Pressure in Vacuum Systems For 95% of the steady-state signal ... 

---