Micrometering valve

The third method would be continuous blowdown through a regulating or micrometer valve. The take-off position for this should preferably be about 250 mm below the working water level and may either be on the side of the shell or on the crown with a dip pipe down to the correct level. If a connection is not available, it is possible to install the valve on the bottom connection prior to the main blowdown valve. 

Extraction System. The flow-through extraction system used in this study is shown in Figure 1. The system is operable up to 400 bar at 200°C. It consists of solvent delivery systems (Fluid 1, Fluid 2, Fluid 3), a flow-through reactor (FR), a set of separator traps (TP1, TP2), and the temperature and pressure control units. The reactor, traps, micrometering valves, and tubing connections are housed in a heated oven. 

Figure 1. Experimental system for supercritical fluid extraction. LF = line filter PG = pressure gauge SV = shut-off valve CV = check valve PHC = preheating coil TC = thermocouple MV = micrometering valve TP = separator trap subscripts r = reactor 1,2 = trap 1,2.

A, Shut-off valve B, Micrometering valve 1, Upper stem 2, Lower stem 3, Flexible coupling 4, Cone (needle) 5, Micrometer scale. 

Even the sample loop should be controlled to the same pressure as the column side to minimize pressure upsets when switching the valve. Frazer et al. (9) found that pressure and flow regulation on all inlets as well as the appropriate micrometering valves (variable restrictors) used to dynamically balance the carrier gas flow and pressure allowed them to switch a 20 foot by 1/8-inch column in or out of a multivalve, multicolumn system with a resulting change in the baseline signal of less than 5 iV. 

Fig. 1. Schematic diagram ot high-pressure apparatus tor enzyme activity tests. A, C02 cylinder B, syringe pump C, equilibrium cell D, sapphire windows E, magnetic stirrer F, white light source G, pressure transducer H, ball valve I, micrometering valve J, relief valve.

Figure 1. Schematic diagram of the experimental apparatus. 1. Gas tube, 2. Cool bath (-10 °C), 3. Pump, 4. Relief valve, 5. Check valve, 6. Pressure meter, 7. Shutoff valve, 8. Loop, 9. Water bath (40 °C), 10. Filter 3.2 mm OD x 0.8 mm thick, 0.25 im 11. Reactor, 12. Micrometering valve, 13. and 15. Cold traps, 14. Cooler (at 0 °C), 16. Cooler (at- 60 °C), 17. Flow meter...

After the desired extraction temperature is reached about 80 g of sample, with particle size of 16-20 mesh-size, is charged into the extraction vessel, supported by two 260 mesh wire disks. The system is immediately closed and the solvent is continuously fed into the vessel by a high pressure pump (TSP, constaMetric 3200 P/F). The pressure is controlled by a micrometering valve from where the solvent and the extract are withdrawn into a glass collector. The experiments were accomplished in 195 min. (unless otherwise stated), isothermally, at constant pressure and using a solvent flow of approximately 3 cmVmin in all... 

Figure 1 shows the simplified flow diagram of the laboratory equipment. First the extractor is filled with the prepared raw material and pressurised. Once the system has attained the required temperature and pressure, the carbon dioxide is expanded into the separator through a micrometering valve, and the extract is precipitated in the separator. The carbon dioxide is evaporated and its volume is measured by a gas meter. 

Flow could not be accurately controlled Improper flow valve installed Changed to micrometering valve... 

A semi-continuous SAS apparatus, as a rule, consists of two pumps used to deliver the liquid solution and supercritical CO2, respectively. A cylindrical vessel is used as the precipitation chamber. The liquid mixture is delivered to the precipitator through an injector. Different arrangements have been proposed in the literature like nozzles, capillaries, vibrating orifices and coaxial devices. Supercritical CO2 is delivered through another inlet port that can be located on the top or the bottom of the vessel. The pressure in the precipitator is regulated by a micrometering valve located at the exit of the chamber. A stainless-steel fiit located at the bottom of the precipitator is used to collect the produced powder. A second vessel located downstream the micrometering valve is used to recover the Uquid solvent. 

R. A. Lee, C. Patel, H. A. Williams, and N. A. Cade, Semiconductor fabrication technology applied to micrometer valves, IEEE Trans. Electron Devices 36(11), 2703, 1989. 

A.B SOLVENT PUMPS C EXTRACTION COLUMN 0 CONSTANT TEMPERATURE BATH E PREHEATER P HEATER-CIRCULATOR G THROUGH - WINDOW RUSK A CELL H REFRIGERATED BATH COOLER t MICROMETERING VALVE... 

Figure 9. Proposed architecture of an electric controlled micrometering valve.

When this phenomena occurs the valve control needs to be halted imtil temperature rises beyond the freezing point. This is propelled by an electric heater installed within the micrometering valve. 

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