Controllable flow rate pump

Thermally Driven Hydrogel Actuator for Controllable Flow Rate Pump in Long-Term Drug Delivery... 

The function of the pump in hplc is to pass mobile phase through the column at high pressure and at a controlled flow rate. One class of pump (constant pressure pump) does this by applying a constant pressure to the mobile phase the flow rate through the column is determined by the flow resistance of the column and any other restrictions between the pump and the detector outlet. Another type (constant flow pump), generates a given flow of liquid, so that the pressure developed depends on the flow resistance. 

Fig. A.S Flow Chart for column Chromatography. The Central part Is the column from the sample and/or solvent is loaded at a controlled flow rate with a pump. The eluates from the column are collected in tubes of a fraction collector.

Pump Section Pulseless flow at controlled flow rates was provided by an Isco model 31A pump. This pump is basically a 350 ml motorized syringe with a capability of generating constant flow rates. 

The amounts of materials fed to a chemical reactor are usually sensed by various types of flowmeters (Fig. 1.4). The proportions of raw materials reacting are known from the ratios of the metered flow rates of raw materials moving into the reactor, which may be adjusted if necessary. Today, flow control and many other variables are designed to be proportional, to control a process more readily. Valves may be set to different flow rates, pump speeds... 

The eluent flow rate is usually controlled by the pump motor speed although there are a few pumps that control flow rate by control of the piston stroke distance. 

There is one report of an offline SPME (or perhaps more properly SPE) extraction system for CE analysis in which the offline extraction is automated. The extraction medium is a monolith placed in the loop position of a six-port loop injector. An injector loop upstream contains a large loop with sample. The sample from the loop in the upstream injector is passed through the extraction medium for a controlled time at a controlled flow rate. Following a rinse, the back extraction solvent is then pumped through the monolith into a collection vial. This system has the advantage of the reproducibility of an automated system, and simultaneously avoids the complexity of the interfacing process. 

It is observed that a marble that has not yet reached the stationary rupture point may have already lost its abifity to roll - a key feature of liquid marbles used in many practical applications. Therefore, further experiments were performed to examine the rolling abilities of enlarged liquid marbles. Marbles with initial size of 0.05 mL were allowed to grow by pumping in controlled volumes of water at controlled flow rate and then were tipped to roU on the substrate. In Fig. 7, the marbles which successfully completed an upside-down rotation... 

Figure 4.22 Schematic of a pumping system based on a pneumatic gas pressure amplifier with microfluidic flow control via feedback from a sensitive flowmeter. In this way the flow rate is maintained regardless of changes in system back pressure or mobile phase viscosity, and changes in flow rates can be established rapidly and accurately, (a) A gradient system in which the mobile phase composition is controlled via flow rates of both mobile phase solvents, (b) A gradient system in which both back pressures and flow rates are monitored volume flow rates = k. (P(- -P ) and Ug = kg.(Pc - Pg) where k and kg are calibration constants, (c) A demonstration of the precision and accuracy with which controlled flow rates can be changed rapidly at total flow rates in the nL.min range, suitable for packed capillary HPLC. Reproduced from company literature (Eksigent 2005, 2006) with permission from Eksigent LLC.

Figure 6.1 Setup of a microreaction screening plant with integrated spectroscopic process analysis. The total microreaction setup can be flooded with a cooling or heating agent to adjust the desired process temperature. External pumps control flow rate and stoichiometryofthe...

The role of the pump is to exert pressure and offer controlled flow rate in order to propel the polymer out of the syringe though the spinneret. The electrospinner user... 

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