Valves four-position

FIGURE 5.11 Timing diagram for comprehensive 2DLC with either a two-position valve (hottom) or four-position valve (top). Repetitive sampling of the first dimension at each time (7i, T2, T3, T4, ,) results in an injection onto the second-dimension column. 

A valve position controller is used to reset the setpoint of the furnace exit temperature controller such that the control valve that is the most open of the four control valves on the hot oil streams flowing through the process heat exchangers is 80 percent open. 

Modifier Pump. The first feature in our adapted design is the introduction of a liquid pump via an instrument controlled VALCO (Model E04, Valeo Instruments, Houston, TX), four position selection valve. We have used an LKB Model 2150, dual piston pump for pumping modifier and entrainer fluids (LKB-Produkter AB, Bromma, Sweden). However, any suitable liquid pump could be substituted. Only pure fluids such as carbon dioxide have been introduced with the Suprex system syringe pump. With the addition of this second pump to deliver liquids, modifier is introduced directly into the extraction vessel. A wide range of alternative fluids and fluid mixtures can be rapidly selected with this dual pumping option. The criteria for selection of a modifier pump include the ability of the pump heads to withstand pressures in the range of 100 to 300 atm and interfacing capabilities, i.e. the ability to be turned on and off by the Suprex contact closure controls. 

Figure 7.7. Schematic diagram of the continuous flow hydride generation system, showing the two positions of the four-port valve (A) for analysis of the test solution and (B) for blank integrations used for changing the test solution. From [115]...

Reactants are pumped from storage, then heated and injected into a mixing chamber (black flow lines). Sample is added to the mixing chamber, the mixture is injected into the flow cell, and the formazan production is monitored every 15 s for 3.5 min. The mixture is flushed, the system is rinsed, and the cycle begins again. The hatched regions are maintained at surface seawater temperatures. The four solenoid valves function most of the time in normally open (NO) or normally closed (NC) positions. A Technicon Autoanalyzer pump and a Bausch and Lomb Spectronic 88 spectrophotometer were used. 

In this section, we describe the operation of the DAB method. With the bed isolated by the four way valve and the three way valve set to the position such that the adsorption cell (C) is connected to the desorption bomb (B). These two are cleaned by either vacuum or heating or a combination of them. 

After the bed is cleaned, the three way valve is set to the position to isolate the cell from the reservoir B, and the adsorption cell is brought to the adsorption temperature with an aid of a flowing inert gas. Once this has been done, the cell is isolated from the flowing gas by using the four way valve F. 

The electrical system is tied into the die close control system and prevents the operation of this system with the safety gate in the open position. The hydraulic system is a pilot valve placed between the die close four-way valve and its solenoid control valve to prevent shifting of the fourway valve with the safety gate open. The mechanical system consists of some form of mechanical interference bar that physically prevents the... 

The microchips are coupled to an SIA system for fully automated determination of MSG. The system is constructed with a syringe pump, a 10-multiposition valve, an enzymatic microchip, and a fluorescence detector. The inlet capillary of the single-channel microchip is connected to a 10-position valve, but in this case, only four ports are used (only beads, sample, waste, and microchip position). The whole system is controlled by a computer using software developed in-house. The fluorescence of the NADH peak is recorded by a chart recorder. 

A bypass pipe connection may be used to isolate the mixing tank from the rest of the dyeing vessel in this way low liquor ratios can also be established. The fluid flow loop through the pipes, however, can be controlled by means of pneumatic valves that direct the fluid from inside to outside, or vice versa, of yam packages. This may be done with the aid of a four-way valve located at the base of the kier. A ventilator valve may be used to direct the liquid in the top of the kier to the mixing tank, and once the kier is full this valve is shut off. Valves may be controlled manually via a control box or via connections to the interface, which in the example in Table 7.2 are BlTs 0-5 of PORT B. All pneumatically operated ball valves on the machine may be fitted with doubleacting actuators. The actuators may be controlled by solenoid/spring spool valves (e.g. 5/2). The term 5/2 denotes a valve with five ports and two positions. 

At any particular moment, only four lines from the rotary valve to the adsorbent chamber are active. Figure 8 shows the flows at a time when lines 2, 5, 9, and 12 are active. When the rotating element of the rotary valve is moved to its next position, each net flow is transferred to the adjacent line thus, desorbent enters line 3 instead of line 2, extract is drawn from 6 instead of 5, feed enters 10 instead of 9, and raffinate is drawn from 1 instead of 12. 

In general, the downhole positive displacement motor constructed on the Moineau principle is composed of four sections (1) the dump valve section, (2) the multistage motor section, (3) the connecting rod section and (4) the thrust and radial-bearing section. These sections are shown in Figure 4-202. Usually the positive displacement motor has multichambers, however, the number of chambers in a positive displacement motor is much less than the number of stages in a turbine motor. A typical positive displacement motor has from two to seven chambers. 

The direction and flow rate of the test and hydraulic fluids are determined by nine three-way valves and six a1r-dr1ven hydraulic pumps that must be sequenced 1n the proper order. The position of the valves 1s determined by six air-driven actuators. Two of the pumps are miniaturized, air-driven, hydraulic pumps used for sample loading and pressurization. One of the remaining four pumps 1s a high-pressure, constant volume, positive displacement, piston metering pump to provide hydraulic pressure, and the other three are positive displacement syringe pumps for In-line addition of additives. 

Port Selector Valve. The inside of the Model 50 Extractor oven was originally equipped with a VALCO 4-port selector valve (Model No. E04). This valve is important in operations regularly utilizing additional co-solvents, inerts or vacuum, as in the introduction of modifiers in our case. When the valve is mounted in its normal fashion, one inlet port controls the flow to four outlet ports which are user selected by position number. When the valve is mounted in a reverse fashion, four inlet ports control the flow to one outlet port. In this manner, the inlet ports can be used to independently deliver various solvents. This reverse configuration is used in our system design. With this configuration, multiple fluids can be introduced to the extraction vessels with ease. 

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