Proper Calibration Procedures Research Articles

Liquidus temperature determination in multicomponent alloys by thermal analysis

Thermal analysis is often used to determine equilibrium phase boundary temperatures such as the liquids. Accurate measurements require proper calibration procedures, which are standard for given instruments. In multicomponent alloys such as RENE N5 and PWA 1484 superalloys, a complex melting behavior associated with the solidification structure was exposed by examining the melting response at different heating rates. The observed variability in the melting signal is related to the sample processing history and is not addressed by the various standard calibration methods or supplemental procedures for different heating rates. The liquidus temperature can be determined under conditions approaching full compositional equilibrium by the application of an interrupted-heating thermal analysis protocol. The approach provides a new strategy for the reliable determination of phase boundary temperatures by thermal analysis.

Quantitative correlation of ethyl acetate diffusion and crystallinity in poly(vinylidene fluoride): photoacoustic FTi.r. approach

The mobility of ethyl acetate (EAc) as a function of crystallinity in poly(vinylidene fluoride) (PVF 2) has been quantified utilizing methodology based on the recently developed rheo-photoacoustic Fourier transform infrared spectroscopy (RPA FTi.r.). The diffusion measurements obtained with the photoacoustic cell, combined with the independent sorption and X-ray measurements, indicate that the crystalline phase of the polymer is impermeable to EAc. Spectroscopic RPA FTi.r. measurements agree with the independently determined diffusion coefficients and the theoretical predictions relating diffusion to the per cent crystalline phase in PVF 2. This study indicates that RPA FTi.r. methodology is highly sensitive to the gas phase analysis and, with the use of proper calibration procedures, can be applied to a quantitative analysis of diffusion in polymers.

Methods in calibration and error analysis for infrared imaging radiometers

Various methods for the calibration and error estimation of imaging radiometers are described. The methodologies are presented in the form of specific examples of the calibration of the Naval Research Laboratory's airborne infrared (IR) radiometric measurement system. Two imaging radiometers are part of this system and are used to perform radiometric measurements on a variety of targets and backgrounds over a spectral range of 3 to 12 μm. The calibration procedures for these radiometers are presented along with an extensive error analysis that examines in detail 16 different sources of error. Such an error analysis clearly illustrates the need for proper calibration procedures.

Calibrating network analyzers with imperfect test ports

The test ports on automatic network analyzers are generally built with an impedance that matches the impedance of the calibration standards. Experimental evidence is presented that substantial impedance discontinuities can be tolerated at the test port interface if proper calibration procedures are observed. The 50- Omega test port on one of the six-ports in a dual six-port network analyzer was replaced with a 75- Omega test port. This test port was then calibrated to look like a 50- Omega test port. Measurements on various devices show that it is possible to make a 75- Omega test port indistinguishable from a 50- Omega test port.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Quality control for solar radiation data

Solar radiation values are difficult to predict or to estimate, due to the multitude of factors affecting radiative transfer in the atmosphere. Whether considering a network of stations or several radiation sensors at a single station, proper calibration procedures of both sensors and data acquisition systems are mandatory. This paper presents a method whereby the interrelationships of signals received from different radiometers at a single site are systematically checked as a means of data control. The various measurements discussed include direct solar, global, diffuse solar and net radiation, albedo, measurements on inclined surfaces and in various bandpasses. The data control method is accomplished by examining ratios, combinations, and comparisons of various measured parameters in addition to calculating some of these parameters by the use of empirical formulae.

Quality assurance for radiation processing

The growth of the Radiation Processing Industry has presented a new set of parameters for QA programs. The large massive doses of radiation required for commercial applications of sterilization, curing, cross linking, etc., needs measurement methods outside the scope of familiar radiation survey instruments. Among the problems that need to be considered by a QA engineer in establishing the validity of a radiation source are; 1) detector response to dose and dose rate, 2) variations due to source spectrum and quality, 3) perturbations due to physical environment, and 4) ease of handling, read-out, and interpretation. In addition, special problems have been encountered in developing proper calibration procedures and selecting transfer instrumentation that supply tracability to primary radiation standards. Thin plastic and dyed plastic films have been used extensively in radiation measurement due to their low cost, ruggedness, ease of handling and read-out, and compatibility to many geometrical configurations. Radiachromic detectors have been developed that minimize problems associated with QA procedures, and may be standardly checked with calibration services available to industry by the National Bureau of Standards. Radiachromic films are now available which provide selected sensitivity over dose ranges of interest to Radiation Processing. Instrumentation is available for single point checks and for one and two dimensional scans which may be used to support QA programs. A variety of instruments may be selected to read-out in 1) transmission, 2) optical density, or 3) directly in absorbed dose.

Diffuse Reflectance Spectroscopy; Applications, Standards, and Calibration (With Special Reference to Chromatography).

The multitude of areas in which diffuse reflectance spectroscopy can be applied has been described in several books and reviews and ranges from color measurements of textiles, pharmaceuticals, building materials, paper and pulp materials etc., to adsorption studies and other basic investigations in physical, inorganic and organic chemistry.The major area of application is still the measurement of color which has become indispensible in the quality control of colored products, dyes and pigments. Color matching practices and techniques with sophisticated instrumentation which can be fully computerized as well as the use of simpler filter instruments for quality control are mentioned.Transferability of reflectance data i.e., color coordinates, depends on the quality of standards particularly when absolute measurements are desired. The difficulty of finding suitable “white standards” with good reflection properties at low UV and with a good long term stability is discussed. Similar arguments hold for sphere coating materials. For the measurement of fluorescing surfaces suitable standards are lacking which renders transfer of such data almost impossible.The usefulness of diffuse reflectance techniques to study adsorption phenomena on small particle adsorbents is demonstrated with a malachite green-o-carboxylic acid lactone system studied by Kortüm. This or similar systems could be adopted to the measurement of relative surface areas on certain chromatographic adsorbents yielding more realistic values than the BET-method.The most recent area of application has been in the field of chromatography for the in situ evaluation of chromatographic zones in flat-bed chromatography, electrophoresis and isoelectric focusing.In chromatography, standardization is less problematic since usually relative measurements are sufficient. On the other hand one has to find suitable calibration procedures. The use of the Kubelka-Munk function is often questionable since we are usually not dealing with layers of infinite thickness and below 300 nm the conventional adsorbents such as silica gel, alumina or cellulose are strongly absorbing. Experiences with a new function combining the laws of Kubelka-Munk and Lambert-Beer are therefore presented.The problem is also to find calibration techniques which account for chromatographic parameters. Until recently it was believed that a quantitative evaluation of chromatograms required a number of reference zones to be developed on the same chromatogram. In our experience this is no longer true. A novel calibration technique which utilizes the concept of transferable calibration factors is discussed. With this approach a quantitative evaluation of a chromatogram with only one reference spot is possible. Here again scanning and data acquisition can be fully automated. The application of proper calibration procedures to differential reflectance techniques and the measurement of multi-component systems is briefly mentioned.Finally it is demonstrated that it is possible to carry out in situ quantitative measurements on low UV absorbing compounds (down to 190 nm) separated on silica gel surfaces, provided suitable techniques and instrumentation are used.

Field Use of Turbine Meters in Sand-Laden Oil

Introduction The need for an accurate, reliable device for metering lease crude oil is a natural outgrowth of efforts by the oil industry to modernize producing facilities to improve operating efficiencies. An initial step in this effort was eliminating the traditional, individual-lease, oil-treating facilities, and oil-storage tanks from which "pipeline-quality" oil was transferred to the pipeline after manual gauging and sampling. In may areas, modernization has replaced the traditional tank battery with lease free-water knockouts and emulsion metering equipment. Centrally located oil-treating stations treat commingled emulsion streams from a number of leases before transferring custody to the pipeline through an automatic custody transfer (ACT) unit. In any measurement system it is imperative that the measurement device not only be accurate, but that it remain repeatable between calibration checks. Many parties, including the oil producer, royalty owners, parties, including the oil producer, royalty owners, out-side working interests, and regulatory agencies, have a vital interest in metering accuracy. An operator's policy to deal honestly and equitably with all associates policy to deal honestly and equitably with all associates requires selecting metering equipment of proven accuracy and providing proper calibration, surveillance, and preventive maintenance procedures for this equipment. preventive maintenance procedures for this equipment. Positive displacement (P) meters have been recognized by industry and regulatory agencies for many years as acceptable measuring devises for metering emulsions from the commingled leases. Regardless of make, the PD meter is designed to divide the fluid stream into a number of discrete-volume segments; the movement of these segments is registered on a counter in terms of gallons, barrels, or other desired units. The PD meters are manufactured with tolerances sufficiently close to assure that the discrete-volume segments remain isolated from each other within the meter. The PD meters, with their inherent close tolerances, are susceptible to internal wear, particularly when handling erosive, sand-laden crudes. The internal wear becomes apparent during periodic provings with a master meter. As internal clearances increase because of erosive wear the meter factor gradually increases to the point where the meter becomes an unsuitable measuring device. A number of fields along the Gulf Coast produce from poorly consolidated sand formations, and produced fluids contain sand in varying quantities. To reduce meter drift and high maintenance costs experienced with the PD meter in sandy crudes, a test program was initiated in Dec. 1971 to evaluate turbine program was initiated in Dec. 1971 to evaluate turbine meters in this service. Based on the satisfactory results of the initial test, the use of the turbines has been expanded to include 56 turbine meters installed in seven fields. Turbine-Meter Description A cross-section of a typical turbine meter is shown in Fig. 1. Meters vary among manufacturers by rotor pitch and proportions, bearing design, materials, etc. but the principle is the same for all. Liquid impinges on the principle is the same for all. Liquid impinges on the rotor, resulting in rotory motion whose speed or frequency is proportional to the rate of flow. JPT p. 139

Evaluation of a reagent-strip method for glucose in whole blood, as compared with a hexokinase method.

The hexokinase method (I) for glucose in biological fluids, proposed by the FDA as a potential national standard method, is compared with the Eyetone/Dextrostix/Control method (II) for measurement of glucose in whole blood. I used a new, two-step calibration procedure based on a 1.30 g/liter standard for the II system. The correlation coefficient for results by the two methods was 0.99 for 142 assays in duplicate. Recovery values were near 100% (I, range 100.0 to 106.2%; II, range 100.8 to 105.1%), and the coefficients of variation were respectively +/- 4.1% and +/- 4.5%. Considering the close correlation between the two methods, together with the simplicity, speed, and convenience of II, I conclude that it has great clinical utility, particularly in emergency situations. The precision and accuracy of II depends greatly on proper calibration and control procedures and on adequate training of the operator.