Gas pressure, control

Use blanketing gas pressure control system to minimize vacuum... 

Non-stoichiometry, which originates from various kinds of lattice defect, can be derived from the phase rule. As an introduction, let us consider a trial experiment to understand non-stoichiometry (this experiment is, in principle, analogous to the one described in Section 1.4.8). Figure 1.1 shows a reaction vessel equipped with a vacuum pump, pressure gauge for oxygen gas, pressure controller for oxygen gas, thermometer, and chemical balance. The temperature of the vessel is controlled by an outer-furnace and the vessel has a special window for in-situ X-ray diffraction. A quantity of metal powder... 

Gas pressure control Our objective is to regulate the pressure p in the tank of Figure PIII.2c, when the inlet pressure p i or the pressure Pi in a downstream process change. Usually, we want to maintain p within a certain range around a desired value, thus making a proportional controller satisfactory for our purpose. 

Gas pressure control, 230, 308-9 Gas storage systems, 230 Gibb s rule, 97... 

Fig. 1. Diagram of a pneumatic amplifier pump, a = gas pressure controller, b, c = valves, d = gas piston, e = liquid piston, f = piston seal, g = solvent Chamber, h = column check valve, i = to column, j = reservoir check valve, k = reservoir.

Gas Pressure Control Device. The gas pressure over the cryogenic liquid in the measuring vessel and guard vessel is subject to atmospheric pressure changes. These changes can lead directly to boil-off measurement errors. Calculations show that the pressure above the cryogenic liquid should be controlled within 0.1 torr however, the atmospheric pressure variation may extend over several torrs. 

Einhorn fermentation saccharometer method CO2 gas pressure control system ... 

The handling and processing of chlorine are nearly identical for the three different types of cell. Important differences are in the cell room header pressure control and the amounts of hydrogen and oxygen contained in the gas. Pressure control requires special attention because it is necessary to maintain a constant differential between the hydrogen and chlorine gas headers that is a small fraction of the (absolute) operating pressure. 

The application of load to the electrolyzers should be made in steps, typically 0.5 kA m at a time, with 15-min waiting periods between steps. The rate of increase at each stage will depend on the need to maintain stable control of the gas pressure control systems. The addition of water to the circulating catholyte should begin at 0.5 kA m. The rate required is nearly linear with current density. In any event, the operating load determines the set point, which can be programmed into a DCS. 

Primary circuit pressure control Cover gas pressure control Active ... 

Let s look at Figure 25-2. The discharge pressure of the compressor is fixed by the absorber fuel gas pressure control (PC). If we start to raise the absorber pressure by closing this PC, the compressor will have to develop more differential pressure. That means it will have to produce more feet of polytropic head (Hp). As shown in Figure 25-1 the compressor will be backed up on its curve. The volume of gas compressed will be reduced. The pressure in the wet gas drum will then rise. The other PC on the spill-back line will then start to close in order to reduce the volume of gas flowing back to the compressor s suction. 

A semi-batch reactor is more difficult to analyze mathematically because at least one of the reactant or product species enters or leaves the system boundaries, thus specific applications should be modeled [1,5]. However, the most typical application for a semi-batch reactor is the presence of one reactant initially contained in a stirred tank reactor and a second reactant continuously added to the reactor, with no flow out of the reactor. The addition of a gas to participate in a liquid-phase reaction is one of the more common situations involving a semi-batch reactor, especially because the rate of addition of the gas can be controlled to keep its partial pressure essentially constant as well as providing quantitative information about the rate of reaction. In addition, there is frequently little or no change in the volume of the liquid phase. Well-mixed autoclave reactors coupled with gas pressure controllers, mass flow meters and computers can nicely provide continuous, real-time rate data related to heterogeneous catalysts used in such gas/liquid systems [6-8]. Again, it must be emphasized that experiments must be performed and/or calculations made to verify that no heat or mass transfer limitations exist. 

Varying the flow of a compressible fluid controls the pressure in a large volume. This process is dominated by a single large capacitance with no dead time. The measurement is normally noise free and, owing to its capacitive nature, is characterized by a slow response and a small process gain. As shown for liquid level control, a proportional controller is more than adequate for gas pressure control. 

In arc deposition, gas pressure control is generally not as critical as in sputter deposition and the gas pressure is monitored in the same manner as for sputter deposition. 

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