Gas transfer pumps

In this chapter, those pumps that are frequently encountered throughout the range of vacuum pressures are dealt with (see Table 3.1). Where necessary, to support the calculations, the operating principles and pump characteristics are reviewed. With gas-transfer pumps operating in the HV/UHV range (typically diffusion or turbomolecular pumps), continuous operation of backing (forevacuum) pumps is required for efficient performance. In such cases, the combination is considered. 

Such pumps are gas-transfer pumps. They are used extensively both to back high-vacuum pumps and to act as devices for achieving pressures in the rough-medium range in activities such as distillation, drying, etc. 

For gas-transfer pumps generally, the compression ratio (k) can be defined as ... 

Gas-transfer pumps such as turbomolecular and diffusion pumps are extensively employed in the HV/UHY range. Both types require backing (forevacuum) pumps with the appropriate characteristics to enable their efficient performance. Aspects of the operation of diffusion pumps (Examples 3.10-3.15) and turbomolecular pumps (Examples 3.16-3.19) were considered. 

Loss control features include combustible gas detectors installed around the containment area and transfer system. A diesel-driven fire pump is capable of handling the emergency demand for 4 hr. A water deluge system has been installed around the storage tank and transfer pump. 

Gas Transfer Gas Capture Pumping Range" Relative Speed... 

The total sample from the probe was transferred to the emission bench location via heavily walled, stainless steel tubing about 91 m (300 ft) long, through the walls of which a low-voltage ac electrical current was passed to maintain approximately 423 K (302°F) wall temperature. The inside diameter of the transfer line was essentially the same as for the probe. The line was vented to atmosphere at the emission bench location after a small portion of the gas sample was withdrawn by the emission bench pumps. The total gas transferred was of the order of 1/2% of the combustor flow, which resulted in a transit time of 2 sec or less to the emission bench. 

All experiments were carried out in a 500 mL cylindrical contact tower (300 mm x 170 mm ID), as shown in Figure II. The ozone was generated from the ozone generator Dwyer Model-2001 (manufactured by the Jelight Co. Ltd. CA, USA) and driven by an air pump with adjustable flow rates. The ozone-oxygen mixture was then ted into the contact tower through a porous plate gas sparer located at the tower s base. 500 mL of dye solution was used during each batch ozonation. A mechanical stirrer worked with the gas diffuser to achieve sufficient recirculation of the dye solution, so a favorable gas transfer rate was expected (Lin S.H., 1993). 

A-1) Benzol transfer pump (A-2) Benzol storage tank (A-3) Benzol feed pump (A-4) Demineralizer (A-S) Chlorine evaporator (B-1) Chlorinator (B-2) Reflux condenser (B-3) Vent gas separator (C) Decanter (D-1) Dilute acid receiver (D-2) Acid still feed pump (D-3) Acid stripping still (D-4) Acid still condenser... 

Cargo tanks are large-capacity cryogenic storage tanks either mounted on a truck body or forming a semitrailer body. The maximum capacity of these units is 11,300 U.S. gal although the most common size used to ship liquefied industrial gas products over the road is 7000 U.S. gal [2]. The truck has a high pressure liquid transfer pump on board which can fill a... 

The transfer of 1 atm of gas into a J. Young NMR tube is most easily accomplished on a high vacuum line with the aid of a U-shaped manometer (Figure 2). During the transfer of gas, the manometer, the NMR tube, and a hose connection to the gas regulator will all be attached to the vacuum manifold. However, before the gas transfer, the solution in the NMR tube must be freeze-pump-thawed to ensure that there is no residual nitrogen atmosphere in the tube. Care must also be taken to thaw the deuterated solution before the gas transfer, so an excess of gas is not condensed into the tube, which may lead to an explosion. Once the vacuum line is charged with 1 atm of gas, the... 

Pressure tanks having a capacity of 3.8 m to 7.7 are often used to transport ammonia from a dealer s terminal to a farm. At a farm ammonia is transferred from nurse tanks to applicator tanks. Figure 10.2 is a photograph showing how a vapor transfer pump is used to transfer ammonia from a nurse tank to an applicator. Some farmers fill the applicator by bleeding ammonia gas from the applicator tank into the atmosphere. Thus, the vapor pressure of the ammonia in the tank causes... 

A low pressure in the system can be supplemented with dry gas. The pump will be sealed by a nitrogen purge controlled at a pressure above that of the tank itself (Section 9.1.8.4B). The standard arrangement includes a recycle line back to the storage tank. This should be at least cracked open before the pump starts. Even after the pump starts, the recycle line should be partly open in order to avoid dead-heading. Before starting liquid transfer but after development of pump pressure, the operator should check the pump shaft and the line valves with an ammonia bottle. Finally, the valves can be opened and the transfer made. 

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