Manometer function

Industrial and Control Instruments. Mercury is used in many industrial and medical instmments to measure or control reactions and equipment functions, including thermometers, manometers (flow meters), barometers and other pressure-sensing devices, gauges, valves, seals, and navigational devices (see Pressure measurements Process control Temperature measurement). Whereas mercury fever thermometers are being replaced by... 

One of the best and most convenient methods of measuring the flow in the terminal is to use the terminal characteristic pressure difference. This requires that the manufacturer of the terminal provide calibration curves, where the flow rate is expressed as the function of the characteristic pressure difference. Some devices have integrated pressure measurement tappings, and the user has only to attach a manometer to measure the pressure difference. 

The flow of fluids is most commonly measured using head flowmeters. The operation of these flowmeters is based on the Bernoulli equation. A constriction in the flow path is used to increase the flow velocity. This is accompanied by a decrease in pressure head and since the resultant pressure drop is a function of the flow rate of fluid, the latter can be evaluated. The flowmeters for closed conduits can be used for both gases and liquids. The flowmeters for open conduits can only be used for liquids. Head flowmeters include orifice and venturi meters, flow nozzles, Pitot tubes and weirs. They consist of a primary element which causes the pressure or head loss and a secondary element which measures it. The primary element does not contain any moving parts. The most common secondary elements for closed conduit flowmeters are U-tube manometers and differential pressure transducers. 

The Varian E-3 was also used for the study of radical cation formation as a function of oxygen pressure in the dark. Oxygen was supplied by a high pressure cylinder, and the lower pressures were controlled by a manometer assembly. The initial studies were per-... 

Haid, Becker and Dittmar Stability Test (Designed for high explosives). 42g of powdered explosive, previously dried over phosphorous pentoxide, is introduced through a side tube into a glass vessel connected with a manometer which is in the form of a U-tube and contains mercury covered with a layer of paraffin oil. The glass vessel is also fitted with a side tap. The ensemble is heated at 75° for several hours and pressures are recorded in mm of Hg as a function of time. The steeper the pressure-time curve the less stable is the explosive... 

Kinetic Experiments. The hydrogenation of alkene was followed by measuring the pressure as a function of time in a constant volume apparatus. The reactor was a 250 ml flask surrounded by a jacket through which thermostated water was pumped. The flask was connected to a vacuum pump, a pressure transducer, a Hg-manometer, a N2-source, and a H2 -source via a condenser. Limitation of the reaction rate because of transport restrictions from the gas phase to the liquid phase was avoided by magnetic stirring. Immediately above the reaction flask a small glass... 

Number of independent equations Number of degrees of freedom Number of independent variables Number of zeros of function Pressure upstream of nozzle in flapper/nozzle system Pressures applied to limbs of manometer tube or pressures downstream and upstream of orifice plate Distillation column pressure Pressure in feedback bellows of pneumatic controller Frictional drag per unit cross-sectional area of manometer tube... 

In the experiments, the filling times for plastisols I and II were measured at various initial pressures and the values indicated by manometer 1-4 were read as a function of time. The data obtained were represented in the dimensionless form as recommended in Sect. 6.3 and compared with the predictions of theory. The typical data... 

C. Extensions of helices having sensitivities of ca. 2 mg mm-- - were read to 0.01 mm with a precision of 0.02 g sorbate per 100 g sorbent. However, because of experimental uncertainties described later, the precision of uptakes is seldom better than 0.1 g/100 g, and sometimes worse. The helices were calibrated at five-degree temperature intervals between 5 and 50°C, and at 100-mg mass intervals up to U00 mg calibration formulae comprising functions of both independent variables were found by a polynominal least-squares fit of all the data. Pressures were measured with large-bore mercury manometers. 

The subscript "true denotes the corrected pressure values while MappM refers to the observed values after they have been corrected for contributions from the background flux. The function a(T) is a small correction that is obtained by intercomparing each cell manometer with a well-calibrated manometer that is always evacuated and maintained at a fixed temperature. Differentiating equation 2 gives... 

The rate of cracking as a function of pressure was studied in the pressure range of 0.4 to 1 atm. in order to test the applicability of the kinetic scheme and to determine the values of the constants k3B0 and G. Operation of the differential reactor at the required pressure was achieved by operating the gas outlet (21, Fig. 3) and the manometer outlet (23, Fig. 3) attached to a large reservoir kept at the required pressure. This made it possible to use the manometer system as before. The condensers were operated at the appropriate temperatures relative to the boiling points of cumene and benzene at the pressure used. 

Pressure measurement devices such as a manometer are used without disturbing the system being monitored. Another type of reacting system that can be monitored involves one of the products being quantitatively removed by a solid or liquid reagent that does not affect the reaction. An example is the removal of an acid formed by reactions in the gas phase using hydroxide solutions. From the reaction stoichiometry and measurements of the total pressure as a function of time, it is possible to determine the extent of the reaction and the partial pressure or concentrations of the reactant and product species at the time of measurement. 

Because gases are compressible, they exert pressure on their surroundings. Pressure is the force that is exerted over a unit area. For example, the atmosphere exerts a pressure known as atmospheric pressure. The Earth s atmosphere is a function of the location and the weather conditions, and it decreases with a higher altitude. The unit of pressure commonly used in chemistry is the atmosphere (atm). The standard atmosphere is 1 atm or a measurement of 760 millimeters of mercury (mm Hg or torr) on a manometer. 

Figure 3.4-4a shows an open-end manometer one end is exposed to a fluid whose pressure is to be measured, and the other is open to the atmosphere. Figure 3.4-4i> shows a differential manometer, which is used to measure the pressure difference between two points in a process line. Figure 3.4-4c shows a sealed-end manometer, which has a near-vacuum enclosed at one end. (Some of the enclosed fluid will vaporize into the empty space, thereby preventing the existence of a perfect vacuum.) If the open end of a sealed-end manometer is exposed to the atmosphere (Pi = Patm) functions as a barometer. 

The steam feeding of the chamber is under the full control of the programmable logic controller (PLC) and data acquisition is achieved by the SCADA system during sterilization cycle control. Vacuum gauges are adapted to function in saturated steam and ambient conditions (MKS capacitance manometer 621). 

With packed columns, it is often convenient to have a manometer attached to the still pot. There is always a pressure drop through the column, and its magnitude is a function of the vapor velocity... 

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