By pressure regulator

Adequate gas control for fhune ionisation d ector gases is usually achieved by pressure regulators supplying gas via constrictors. Some flame ionisation detectors reqiure very precise control of hydrogen flow, best achieved by mass flow control. 

The third-transition-series metal hexafluorides are excellent for this purpose in that they constitute a set, well graded in oxidizing power [7], yet dmost isodimensiond moreover, as gases they may be readily transported and applied, and their activity controlled, to some extent, by pressure regulation. 

In addition to the cell temperature, the flow rate, the inlet and outlet pressures, and the relative humidity (RH) of the gaseous reactant should be controlled. The temperature is controlled by the aqueous electrolyte into which the electrode/membrane assembly is immersed. The electrolyte temperature can itself be controlled by either a water or an oil bath. The flow rate of the gaseous reactant can be controlled by a flow meter or a mass flow controller. The inlet and back pressures of the reactant can be controlled by pressure regulators. The RH can be controlled by passing the reactant through a humidifier at a predetermined temperature. There are several types of humidifiers to choose from. The cheapest one is a sparging bottle that contains water. 

The gas-liquid and liquid-solid mass transfer resistances are suppressed by vigorous agitation of the reactor contents, and the mass transfer resistance inside the catalyst particles is minimized by using finely dispersed particles (of micrometer scale). The addition of the gas-phase component is controlled by pressure regulation thus, the pressure in the gas phase is kept constant, which implies that the mass balance of the gas phase can be excluded from the mathematical treatment. The concentrations of dissolved gases in the liquid phase are equal to the saturation concentrations (Chapter 6). Under these circumstances, the mass... 

Gas flow rates were monitored by Matheson mass flow transducers and pressures were controlled by pressure regulators. Flow rates, temperatures and reactor pressure were recorded at 10 s intervals by a data acquisition system interfaced with a Hewlett Packard 1000 mini-computer. Details regarding the reactor system will be presented elsewhere. ... 

Most continuous pressure filters available (ca 1993) have their roots in vacuum filtration technology. A rotary dmm or rotary disk vacuum filter can be adapted to pressure by enclosing it in a pressure cover however, the disadvantages of this measure are evident. The enclosure is a pressure vessel which is heavy and expensive, the progress of filtration cannot be watched, and the removal of the cake from the vessel is difficult. Other complications of this method are caused by the necessity of arranging for two or more differential pressures between the inside and outside of the filter, which requires a troublesome system of pressure regulating valves. 

In most utibty boilers, steam pressure regulation is achieved by the throttling of turbine control values where steam generated by the boiler is admitted into the steam turbine. Some modem steam generators have been designed to operate at pressures above the critical point where the phase change between Hquid and vapor does not occur. 

The chromaffin cells of the adrenal medulla may be considered to be modified sympathetic neurons that are able to synthesize E from NE by /V-methylation. In this case the amine is Hberated into the circulation, where it exerts effects similar to those of NE in addition, E exhibits effects different from those of NE, such as relaxation of lung muscle (hence its use in asthma). Small amounts of E are also found in the central nervous system, particularly in the brain stem where it may be involved in blood pressure regulation. DA, the precursor of NE, has biological activity in peripheral tissues such as the kidney, and serves as a neurotransmitter in several important pathways in the brain (1,2). 

The total feed flow is set for a higher level than it is needed for the experiment. The excess feed is released by a back pressure regulator (BPR at the bottom of the picture), e.g., at 21 atm and is led to the analyzer. The... 

A forward pressure regulator (FPR) reduces the pressure and keeps the reactor at 7.5 psig. Reactor pressure is Indicated and recorded by (PIR) and temperature by (TIR). Discharge flow from the reactor is measured by a flow transmitter (FT) and after correction for temperature and pressure the Flow is Recorded on (FR). 

Ensure that the rated maximum inlet pressure of the regulator is not less than the eylinder supply pressure. (Eor eylinder pressures up to 200 bar, pressure regulators should eomply with BS 5741. Eor higher eylinder pressures eheek with the manufaeturer that the pressure regulator has been shown to be suitable by appropriate testing.)... 

Figure 10.4 Schematic representation of the multidimensional GC-IRMS system developed by Nitz et al. (27) PRl and PR2, pressure regulators SV1-SV4, solenoid valves NV— and NV-I-, needle valves FID1-FID3, flame-ionization detectors. Reprinted from Journal of High Resolution Chromatography, 15, S. Nitz et al, Multidimensional gas cliro-matography-isotope ratio mass specti ometiy, (MDGC-IRMS). Pait A system description and teclinical requirements , pp. 387-391, 1992, with permission from Wiley-VCFI.

Butane cylinders, which are so widely used for domestic service, are now provided with a self-sealing clip-on valve. The pressure regulator, which is normally attached directly onto the cylinder outlet, is fitted by a simple push-on or snap-on action and is provided with a lever, which will open or shut the cylinder valve. 

Most compressed air equipment operates at about 6 bar (gauge) and it is usual for the compressor to deliver air into the mains at 7 bar (gauge) in order to allow for transmission losses (see Tables 35.1-35.4). If some of the air is to be used at a lower pressure (for example, for instmment control) the pressure is reduced by means of a pressure regulator to the required line pressure. 

Air reservoirs are designed to receive and store pressurized air. Pressure regulating devices are installed to maintain the pressure within operational limits. When the air reservoir is pressurized to the maximum pressure set-point, the pressure regulator causes the air compressor to off-load compression by initiating an electrical solenoid valve to use lubricating oil to hydraulically hold open the low pressure suction valve on the compressor. 

A condenser pressure regulator can be in the form of a pressure-operated bleed valve in a bypass across the condenser, to divert hot gas to the receiver. The valve diaphragm is balanced by a pre-set spring and will open the bypass if the condensing pressure falls. A similar effect can be obtained by a pressure-operated valve between the condenser and the receiver, to restrict the flow and allow liquid to accumulate in the condenser, reducing its efficiency. For operating... 

Check all pressure relief valves. These can open to relieve excess pressure in the system caused by temperature changes or failing pressure regulator on the MU line. 

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