Pumping chamber

The heart, a four-chambered muscular pump has as its primary purpose the propelling of blood throughout the cardiovascular system. The left ventricle is the principal pumping chamber and is therefore the largest of the four chambers in terms of muscle mass. The efficiency of the heart as a pump can be assessed by measuring cardiac output, left ventricular pressure, and the amount of work requHed to accomplish any requHed amount of pumping. 

Beyond the complexities of the dispersive element, the equipment requirements of infrared instrumentation are quite simple. The optical path is normally under a purge of dry nitrogen at atmospheric pressure thus, no complicated vacuum pumps, chambers, or seals are needed. The infrared light source can be cooled by water. No high-voltage connections are required. A variety of detectors are avail-... 

The liner (grey area) is m full-capacity position with the seal point at the top anC the pumping chamber at (he bottom All lipuid coming Into the pump at the left is moving out of it at the right. 

Temperature rise of water, °F Volume of tank or system, cu ft Volume of vessel or system, liters Volume of pumping chambers, liters Flow rate, Ibs/hr... 

The flow capacity of a pump can be expressed as its displacement per revolution or by its output in gallons per minute (gpm). Displacement is the volume of liquid transferred in one complete cycle of pump operation. It is equal to the volume of one pumping chamber multiplied by the number of chambers that pass the outlet during one complete revolution or cycle. Displacement is expressed in cubic inches per revolution. 

Most pumps that are used in hydraulic applications have a fixed displacement which cannot be changed except by replacing certain components. However, in some, it is possible to vary the size of the pumping chamber and thereby the displacement by means of external controls. Some unbalanced vane pumps and many piston units can be varied from maximum to zero delivery or even to reverse flow without modification to the pump s internal configuration. 

The net head or pressure measured in ft. or m that causes a liquid to flow through the suction side of a pump, enter the pump chamber, and reach the impeller. When the source of liquid is above the pump, NPSH equals the barometric pressure plus the static head, less the entrance head, frictional losses in the suction piping and vapor pressure of the liquid. When the source of liquid is below the pump, NPSH equals the barometric pressure less the static head, entrance head, frictional losses in the suction piping and vapor pressure of the liquid. NPSH is specific for each pump design and application and must be supplied by the manufacturer. 

The DBMS setup and experimental procedures used in this study were the same as described in more detail elsewhere [Jusys et al., 2001]. Briefly, the DBMS setup consisted of two differentially pumped chambers, a Balzers QMS 112 quadrupole mass spectrometer (MS), a Pine Instruments potentiostat, and a computerized data acquisition system. 

The partial pressures of the stable neutral molecules in the discharge (silane, hydrogen, disilane, trisilane) can be measured by a quadrupole mass spectrometer (QMS). The QMS usually is mounted in a differentially pumped chamber, which is connected to the reactor via a small extraction port [286]. In the ASTER system a QMS is mounted on the reactor that is used for intrinsic material deposition. The QMS background pressure (after proper bake-out) is between 10 and 10 mbar. The controllable diameter in the extraction port is adjusted so that during discharge operation the background pressure never exceeds 10"" mbar. 

The total of eight individually pumped chambers separated by small orifices keeps a pressure ratio of 20 orders of magnitude between the He source reservoir and detector. This is done at the expense of the flexibility of the scattering geometry. In the case of the apparatus shown in Fig. 2, the angle between incident and outgoing beam is fixed at 9, -I- 9, = 90°. 

A final aspect of GPC solvent delivery relates to the solvent reservoirs themselves. The ability to perform in situ helium degassing of solvents, provide inert gas blankets over solvents, and protect solvents from contamination from external sources are worth consideration from the standpoints of convenience and safety alone. If these features are provided for, it is a small step to also provide a small positive pressure, say 10 psi or so, to the solvent reservoir. This positive pressure helps minimize the formation of solvent vapors in the pump chamber during the refill part of the pump stroke, and improves the flow rate reproducibility of rapid-refill type pumps delivering high-vapor-pressure solvents. 

Pumps which transport quantities of gas from the low pressure side to the high pressure side vi/ithout changing the volume of the pumping chamber (Roots pumps, turbomolecular pumps)... 

The valves are arranged in such a way that during the phase where the volume of the pumping chamber increases it is open to the intake line. During compression, the pumping chamber is linked to the exhaust line. 

Lower dead point - slot in suction channel is quite free, and pumped-in gas (arrow) enters freely into the pumping chamber (shown shaded)... 

The gas ballast facility (see Fig. 2.13) prevents condensation of vapors in the pump chamber of the pump. When pumping vapors these may only be compressed up to their saturation vapor pressure at the temperature of the pump. If pumping water vapor, for example, at a pump temperature of 70 °C, the vapor may only be compressed to 312 mbar (saturation vapor pressure of water at 70 °C (see Table XIII In Section 9)). When compressing further, the water vapor condenses without Increasing the... 

Pump chamber is separated from the vessel - compression begins... 

Content of pump chamber is already so far compressed that the vapor condenses to form droplets - overpressure is not yet reached... 

Pump chamber is separated from the vessel - now the gas ballast valve, through which the pump chamber is filled with additional air from outside, opens - this additional air is called gas ballast... 

At the beginning of a pump down process, the gas ballast pump should always be operated with the gas ballast valve open. In almost all cases a thin layer of water will be present on the wall of a vessel, which only evaporates gradually. In order to attain low ultimate pressures the gas ballast valve should only be closed after the vapor has been pumped out. LEYBOLD pumps generally offer a water vapor tolerance of between 33 and 66 mbar. Two-stage pumps may offer other levels of water vapor tolerance corresponding to the compression ratio between their stages -provided they have pumping chamber of different sizes. 

Figs. 2.26 and 2.27 demonstrate the differences in design. Shown is the course of the pressure as a function of the volume of the pumping chamber by way of a pV diagram. 

Due to the work done on compression in the individual pumping stages, multi-stage claw pumps require water cooling for the four stages to remove the compression heat. Whereas the pumping chamber of the pump is free of sealants and lubricants, the gear and the lower pump shaft are lubricated... 

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