Liquid delivery system

This paper describes work on equipment and instrumentation aimed at a computer-assisted lab-scale resin prep, facility. The approach has been to focus on hardware modules which could be developed and used incrementally on route to system integration. Thus, a primary split of process parameters was made into heat transfer and temperature control, and mass transfer and agitation. In the first of these the paper reports work on a range of temperature measurement, indicators and control units. On the mass transfer side most attention has been on liquid delivery systems with a little work on stirrer drives. Following a general analysis of different pump types the paper describes a programmable micro-computer multi-pump unit and gives results of its use. 

Traditional Apparatus. As indicated earlier, liquid delivery systems for controlled rate addition of monomers and initiators have tended to rely upon constant speed piston pumps (19) in which volumetric control is achieved by manual adjustment of stroke length, and monitoring is by discharge from measuring cylinders. 

Water was used as the liquid phase. The liquid delivery system consists of a feed tank, pump, and a flow indicator. Water is recycled, as well as added if necessary, to maintain a constant suction head at the pump. The in-house air system was used as the gas delivery system through a rotameter. Air enters the setup at a point below the packing. Two taps are mounted at the inlet and outlet of the packed column for pressure drop measurement. 

Response time depends on the properties of the sensor system (such as cell volume and gas/liquid-delivery system — see Chapter 6), on the properties of the coating (i.e., thickness), and on sorption/reaction kinetics. Rates of adsorption... 

Fig. 8 Generalized schematic diagram of a liquid delivery system.

Table 1-2. Advantages and disadvantages of Liquid Delivery System (LDS).

The supply rates of the liquid were eontrolled in the range from 0.05 to 1 g/h by a so-called p-Flow mass-flow meter (Bronkhorst, High-Teeh B.V.). At room temperature, the liquid was drawn from a pressurised container with an inert gas blanket and measured by the liquid mass-flow meter. The required flow rate was controlled to the set-point value by a control valve (C), forming an integral part of the liquid flow and earner gas mixing valve (M). The formed mixture was subsequently led into the evaporator to achieve total evaporation (E). This explains the abbreviation of CEM , shown in Fig. 1, viz. Controller-Evaporation-Mixing, the three basic functions of the liquid delivery system. The main features of this liquid delivery system are a) accurately controlled gas/liquid mixture, b) fast response, c) high reproducibility, d) very stable vapour flow, and e) flexible selection of gas/liquid ratio. 

Figure 7.15 Personal OPLC BS 50 system including separation chamber for 20 X 20 or 20 X 10 cm plates, holding unit, layer casette, and liquid delivery system. (Photograph courtesy of OPLC-NIT Engineering Co., Ltd., Budapest,...

The liquid delivery systems operate at a low pressure. A peristaltic pump capable of delivering fluid at a controlled rate is desirable. The liquid is transported from the solution vessel through the tubing, and atomized using a two-fluid (binary) nozzle in the fluid bed processor. 

Figure 13 Personal OPLC BS-50 system. 1, separation chamber 2, holding unit 3, layer casette 4, liquid delivery system.

Meister, A. Gabi, M. Behr, P. Studer, R Voros, J. Niedermann, R BitterU, J. etal. FluidFM Combining atomic force microscopy and nanofluidics in a universal liquid delivery system for single cell applications and beyond. Nano Lett 2009, 9, 2501-2507. 

Ghosh LK, Ghosh NC, Thakur RS, Pal M, Gupta BK. 1997. Design and evaluation of controlled-release W/O/W multiple-emulsion oral liquid delivery system of chlorpheniramine maleate. Drug Dev Ind Pharm 23 1131-1134. 

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