Instruments for measuring

A recent design of the maximum bubble pressure instrument for measurement of dynamic surface tension allows resolution in the millisecond time frame [119, 120]. This was accomplished by increasing the system volume relative to that of the bubble and by using electric and acoustic sensors to track the bubble formation frequency. Miller and co-workers also assessed the hydrodynamic effects arising at short bubble formation times with experiments on very viscous liquids [121]. They proposed a correction procedure to improve reliability at short times. This technique is applicable to the study of surfactant and polymer adsorption from solution [101, 120]. 

The traditional instruments for measuring emission and absorption spectra described above set the standard for the types of infonnation which can be obtained and used by spectroscopists. In the more recent past, several new... 

A simple instrument for measuring absorbance that uses absorption or interference filters to select the wavelength. 

An instrument for measuring fluorescence that uses filters to select the excitation and emission wavelengths. 

Time, Cost, and Equipment In comparison with competing methods, potentiome-try provides a rapid, relatively low-cost means for analyzing samples. Commercial instruments for measuring pH or potential are available in a variety of price ranges and include portable models for use in the field. 

Once inside the hot plasma, which is at a temperature of about 8000 K and contains large numbers of energetic electrons and ions, the sample molecules are broken down into their constituent elements, which appear as ions. The ions are transported into a mass analyzer such as a quadrupole or a time-of-flight instrument for measurement of m/z values and ion abundances. 

Atoms of elements are composed of isotopes. The ratio of natural abundance of the isotopes is characteristic of an element and is important in analysis. A mass spectrometer is normally the best general instrument for measuring isotope ratios. 

J. W. Butier and co-workers, FastKesponse Zirconia Sensor-Fased Instrument for Measurement of the Air (Fuel Katio of Combustion Exhaust, SAE 840061, Society of Automotive Engineers, Warrendale, Pa., 1984. 

Anemometers An anemometer may be any instrument for measurement of gas velocity, e.g., a pitot tube, but usually the term refers to one of the following types. 

A turbine flowmeter consists of a straight flow tube containing a turbine which is free to rotate on a shaft supported by one or more bearings and located on the centerline of the tube. Means are provided for magnetic detection of the rotational speed, which is proportional to the volumetric flow rate. Its use is generally restric ted to clean, noncorrosive fluids. Additional information on construction, operation, range, and accuracy can be obtained from Holzbock (Instruments for Measurement and Control, 2d ed., Reinhold, New York, 1962, pp. 155-162). For performance characteristics of these meters with liquids, see Shafer,y. Basic Eng., 84,471-485 (December 1962) or May, Chem. Eng., 78(5), 105-108 (1971) and for the effect of density and Reynolds number when used in gas flowmetering, see Lee and Evans, y. Basic Eng., 82, 1043-1057 (December 1965). 

Resistance is measured either indirectly by separate current and voltage measurements or directly by comparison in a bridge. In both cases it involves two measurements. The instruments for measuring the current and voltage U2 have to be chosen so as to make the deviation from U and I in Fig. 3-2 as small as possible. 

Search, detection, navigation, guidance, aeronautical, and nautical systents and Instruments Laboratory apparatus and furniture Automatic controls for regulating residential and commercial environments and appliances Industrial instruments for measurement, display, and control of process variables and related products... 

By connecting manometer hoses to both output pressures given by the tube, the pressure difference Ap can be measured directly. The barometric pressure and the fluid temperature are required for the determination of the fluid density. The Pitot-static tube is not a suitable instrument for measuring low velocities. It can be applied in cases where the flow velocity is high... 

Instrument for measuring effective static pressure at gas-metenng device. 

An instrument for measuring nitrogen oxides based on chemiluminescence is shown in Fig. 13.49. The ozone required for the reaction is produced in the ozone generator, which is part of rhe device. One of the reaction chamber walls is an optical filter through which a red-sensitive photomultiplier tube measures the chemiluminescence radiation intensity and converts it into a current signal. 

Optical anemometer An instrument for measuring gas flow rate using a laser, in which small frequency shifts are visualized as interference fringes. 

Optical particle counter An optical-electronic instrument for measuring the numbei" of airborne particles in different size ranges. 

There are several instruments for measuring temperature as follows. 

Instruments for measuring the velocity as a pressure effectively convert this energy into pressure. The transducer used is the Pitot tuhe (Figure 27.3), which faces into the airstream and is connected to a manometer. The outer tuhe of a standard pitot tuhe has side... 

In the present chapter consideration is given to various types of indicator and reference electrodes, to the procedures and instrumentation for measuring cell e.m.f., to some selected examples of determinations carried out by direct potentiometry, and to some typical examples of potentiometric titrations. 

See under Closed Bomb (or Vessel) and Instruments for Measuring Pressures Developed by Explosives or Propellants in Vol 3, C330-L to C345-R... 

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