Three-way solenoid valves

Three-Way Solenoid Valve Latch Type With Manual Reset... 

Feeds to the reactor (air, nitrogen, and methane) were fed continuously through rotameters and needle valves for flow control. The gases then passed through three-way solenoid valves activated by timers to give desired feed program. A typical run" consisting of the sequence of N2, A1r, N2,... 

For the laboratory prototype a Gilson fraction collector was used. The whole setup as depicted was named MICROTAUROS (Fig. 15.14) (microreactor for automated reaction optimisation) and worked fairly well with only a few drawbacks. The length of the tube necessary for reaching every position on the fraction collector rack precluded very short reaction times. Higher pump rates would compromise the advantage of a laboratory system with the rather small amoimts of materials and small syringes. A much more severe drawback is the fact that a three-way solenoid valve had to be used. In the equilibrium phase the material stream is switched to waste and only diverted for collection of analytical samples. 

A sheathed thermocouple was inserted axially in the middle of the catalytic bed. Local bed temperatures were recorded continuously by a data acquisition device. A three way solenoid valve (Jefferson model 365) activated by timers was used to generate liquid flowrate variations. Hydrogen was presaturated with AMS. Experiments were performed randomly. Operating conditions used in most of the experiments are given in Table 3... 

The MCFIA technique, devised by B.F. Reis et al. [10], exploits fast-switching three-way solenoid valves (see Figure 1.11). Earliest MCFIA systems used a single-channel propulsion system to aspirate the liquids via individual valves. Since aspiration devices tend to insert air bubbles or degas liquids in the system, it is preferable to use liquid propulsion devices such as peristaltic or multipiston pumps instead. 

Three-way solenoid valve. (For color version of this figure, the reader is referred to the online version of this book.)... 

The first design of LIS (Figure 1.27) [30] consisted of an automatic syringe pump equipped with a three-way solenoid valve at the head and two optical fibers mounted to the syringe, enabling the whole procedure (i.e. microextraction and detection) inside a glass syringe, connected to the central port of a selection valve. 

East-switching three-way solenoid valves constitute the technical basis of the multicommutated flow analysis technique and also are common elements of multisyringe flow injection analysis systems. We... 

An automated system for potentiometric determination of free and total cyanide in wastewaters is by employing a homogeneous membrane tubular ion-selective electrode [38]. After the electrode is assembled, it is connected to a system composed of 3 three-way solenoid valves, sample line, carrier line, acid stream, and gas diffusion chamber. A turbo pascal computer program performs all the steps involved in data acquisition and processing. The proposed analytical procedure offers operational simplicity, since detection is performed by a cyanide ion-selective tubular electrode, and is fast and easy to assemble. 

FIGURE 4.2 Schematic depiction of an MCFIA system for the spectrophotometric determination of iron. C carrier (perchloric acid solution) D detector (480 nm) PP peristaltic pump R reagent (thiocyanate solution) RC reaction coil S sample V three-way solenoid valve W waste. 

MCFIA has not had great success as a novel flow technique in itself. There are few publications of MCFIA methods in comparison with other flow techniques. However, three-way solenoid valves have been widely implemented in other flow systems. Thus, three-way solenoid valves have been one of the major contributions of MCFIA. 

FIGURE 4.5 MCFIA system for mercury determination in fish by cold vapor absorption spectrophotometry. AAS atomic absorption spectrometer quartz cell Ar argon carrier gas C carrier (HCl) GLS gas-liquid separator PP peristaltic pump R reducing reagent (NaBFL, in NaOH) RC reaction coil V three-way solenoid valve and W waste. 

FIGURE 4.6 Schematic diagram of an MCFIA system for photometric titration procedures. C carrier (H2O) MB magnetic stirring bar Mm DC mini-motor PP peristaltic pump Rl dye indicator solution R2 titrant solution S sample TC titration chamber V three-way solenoid valve and W waste. 

FIA. Each syringe has a three-way solenoid valve (N-Research, Caldwell, NJ, USA) at the head, which facilitates the application of multicommutation schemes allowing four kinds of liquid displacement on-dispense, off-dispense, on-pick-up, and off-pick-up. High chemical robustness is provided by the use of resistant polymers, for example, poly(ethylene-co-tetrafluoroethylene) (ETFE) (head valves) and PTFE (piston heads, poppet flaps). 

FIGURE 4.9 MSFIA system for the determination of total antioxidant capacity using the DPPH assay. C carrier (ethanol solution) D detector HC holding coil R 2,2-diphenyl-l-pirylhydrazyl reagent in carrier RC reaction coil S1-S4 syringes S sample or antioxidant standard solution V three-way solenoid valve and W waste. 

Figure 4.11 shows an MSFIA system coupled to cold vapor atomic fluorescence spectrometry (CV-AFS) for mercury determination in rice [47]. As can be seen for sample pick-up an extra three-way solenoid valve (V) was connected to syringe 1 (SI), syringe 2 (S2) was used to dispense the reducing solution and a solenoid micropump was used to remove the liquid-excess from the gas-liquid separator, keeping a constant liquid volume in it. 

FIGURE 4.10 Schematic depiction of an multisyringe chromatography system applied to oxalate determination in beer and urine with chemiluminescence detection. HC holding coil KRC knotted reaction coil MC monolithic column—10 mm x 4.6 mm Qg coated with cetyltrimethyl ammonium bromide (CTAB) PMT photomultiplier Rl tris(2,2 -bipyridyl)dichlororuthenium(II) solution R2 cerium(IV) solution S syringe SFC spiral flow cell V three-way solenoid valve and W waste. 

FIGURE 4.11 MSFIA CV-AFS system for the determination of mercury. D Fluorescence detector GD gas dryer GL gas-liquid separator HC holding coil MP micropump Rl nitric acid R2 SnCl2 + HCl RC reaction coil S1-S4 syringe S sample SGC spray generator coil V three-way solenoid valve and W waste. 

FIGURE 4.15 MPFS for iron determination. C carrier D detector E eluent MP micropump O oxidizing agent R chromogenic reagent RC reaction coil S sample SPE column containing the SPE disk V three-way solenoid valve and W waste. 

FIGURE 5.9 MSC system for isocratic separation. MS multisyringe burette M manometer V1-V3 solenoid valves El two-way connector E2 three-way solenoid valve MP mobile phase S sample W waste RP-18 monolithic column DAD diode array detector and SC sample coil. (Reprinted from Gonzalez-San Miguel, H. M., J. M. Alpizar-Lorenzo, V. Cerda-Martin, 2007. Talanta 72 296-300. With permission.)... 

Determination of hydrosoluble vitamins (AA, thiamine, riboflavin, and pyridoxine). The flow manifold is designed with computer-controlled three-way solenoid valves... 

The concurrent BKF system consists of four elements A three-way solenoid valve (BKF valve) in the carrier gas line, a wide-bore pre-column, a purged T-connector in the GC oven and a flow restrictor (see Figures 2.60 and 2.61). The analytical column is pushed about 3-5 cm into the wide-bore pre-column to ensure full chromatographic integrity avoiding analyte contact to the surface of the T-piece. 

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