ASTM standards temperature calibration

ASTM E 967-92, Standard Practice for Temperature Calibration of Differential Scanning Calorimeters and Differential Thermal Analyzers, 1992. 

Accurate temperature calibration using the ASTM temperature standards [131, 132] is common practice for DSC and DTA. Calibration of thermobalances is more cumbersome. The key to proper use of TGA is to recognise that the decomposition temperatures measured are procedural and dependent on both sample and instrument related parameters [30]. Considerable experimental control must be exercised at all stages of the technique to ensure adequate reproducibility on a comparative basis. For (intralaboratory) standardisation purposes it is absolutely required to respect and report a number of measurement variables. ICTA recommendations should be followed [133-135] and should accompany the TG record. During the course of experiments the optimum conditions should be standardised and maintained within a given series of samples. Affolter and coworkers [136] have described interlaboratory tests on thermal analysis of polymers. 

A standard procedure for the temperature calibration of differential thermal analysers and differential scanning calorimeters has been published as ASTM E 967 (1999). In the two point method two calibrants are chosen to bracket the temperature range of interest. It is assumed that the correct temperature T is related to the experimental temperature Texp by the relationship,... 

Calibration of TA instrumentation and development of standards for calibration continue to be administered by ICTAC in conjunction with ASTM. The standardization Committee of ICTAC has certified a range of materials for temperature calibration of TA systems, and in addition, standards for calibration of mass (known as Class M Standards ) are available for this purpose. A range of certified reference materials are available for enthalpy calibration in DSC. Temperature calibration for TMA and dynamic mechanical analysis (DMA) is effected by using disks of pure metals (silver, aluminum, and tin) separated by alumina disks. Load or force calibration for DMA is a complex process involving the use of calibrated weights. Temperature calibration for DETA is effected by measuring the melting transition of benzoic acid and dielectric calibration is... 

Hakvoort (16) and also Della Gatta and Barczynska (17) advocate certain solid-state first-order transitions for use as subambient temperature standards. For relatively low temperature ranges, such as the glass transitions (Tg) for elastomers, Tan and Sabbah (18) have proposed the melting transitions of various organic compounds. Certified reference materials for heat capacity calibration, which are recommended by International Union of Pure and Applied Chemistry (lUPAC), are also available (Ref 5, pp. 46 and 353-356). Two ASTM standards document procedures for temperature (ASTM E967) and heat-fiow (ASTM E968) calibration in DSC. 

A temperature calibration procedure for TMA has been proposed (53-55) and subsequently included as an ASTM method (Test Method for Temperature Calibration of Thermomechanical Analyzers, E1363-90). It uses a penetration probe and the melting temperature of one or more standard materials. Pure metals with sharp melting points are the standards often used. An open DSC pan may be used to contain the calibrant material. Another potential material would be the selected shape memory alloy, reported to be reproducible to 1°C (56). Several reviews on temperature calibration for TMA have been published based on ASTM efforts in this area (54,55). Sircar (26) suggests that, when used for elastomer evaluation, temperature calibration for TMA should be conducted with low melting liquids as in DSC. For calibration of the expansion, one manufacturer s manual (TA Instruments) recommends aluminum for calibrating the linear expansion parameter. Other calibration standards suggested for the linear coefficient of thermal expansion (CTE) are lead (57) and copper (58). 

ASTM E1363, test method for Temperature Calibration ofThemomechani-cal Analyzers, provides a standard method for calibrating TMA instruments (Seyler and Earnest 1991 and 1992). In the recommended ASTM method, three standard materials (phenoxybenzene, Pb, and In) are used. 

Finally, since the TGA8S1° detects transitions from their temperature lags, events without associated weight loss, such as melting (seen previously) are also detectable This makes true temperature calibration possible with melting point standards. Classically designed systems with itv temperature measurements that do not detect this lag must use other methods described in the ASTM procedure One such method uses a slight... 

The use of TMA (and DMTA) to measure the properties of thin films and fibers is growing. TMA can be used, for example, to observe the effects of processing on specimen dimensions (e.g. shrinkage and anisotropy) and transition temperatures. As these properties are often measured with long specimens in a tensile arrangement, a new type of temperature calibration may be required. Although no ASTM test method exists for such a purpose, Moscato [3] used indium and lead foils as melting point standards at a... 

This is the essential characteristic for every lubricant. The kinematic viscosity is most often measured by recording the time needed for the oil to flow down a calibrated capillary tube. The viscosity varies with the pressure but the influence of temperature is much greater it decreases rapidly with an increase in temperature and there is abundant literature concerning the equations and graphs relating these two parameters. One can cite in particular the ASTM D 341 standard. 

The viscosity is determined by measuring the time it takes for a crude to flow through a capillary tube of a given length at a precise temperature. This is called the kinematic viscosity, expressed in mm /s. It is defined by the standards, NF T 60-100 or ASTM D 445. Viscosity can also be determined by measuring the time it takes for the oil to flow through a calibrated orifice standard ASTM D 88. It is expressed in Saybolt seconds (SSU). 

The bulk density of the feedstock at ambient temperature and pressure should be measured prior to the design of a new screw, especially if it contains in-plant recycle resin. The measurement method is extremely simple and requires only a calibrated cell and a scale. A calibrated measuring cell with a volume of 500 cm can easily be constructed by welding a thin-walled metal pipe to a flat sheet of metal, as shown in Fig. 4.2. The bulk density is measured by filling the cell with feedstock, leveling the top with a steel ruler, and then weighing the cell contents. A more formal measurement technique was developed by ASTM as standard method D1895. 

Fourier transform infrared (FTIR) spectroscopy of coal low-temperature ashes was applied to the determination of coal mineralogy and the prediction of ash properties during coal combustion. Analytical methods commonly applied to the mineralogy of coal are critically surveyed. Conventional least-squares analysis of spectra was used to determine coal mineralogy on the basis of forty-two reference mineral spectra. The method described showed several limitations. However, partial least-squares and principal component regression calibrations with the FTIR data permitted prediction of all eight ASTM ash fusion temperatures to within 50 to 78 F and four major elemental oxide concentrations to within 0.74 to 1.79 wt % of the ASTM ash (standard errors of prediction). Factor analysis based methods offer considerable potential in mineral-ogical and ash property applications. 

Thermodilatometry is a particular case of thermomechanical analysis in which change in a dimension is monitored as a function of temperature under negligible load and, normally, measures the linear coefficient of expansion. It has become the most usual method and there is an ISO standard for plastics5. A British standard is identical, published as BS ISO 11359-2. ASTM has a TMA method for materials in general6 and also a formal procedure for the calibration of the analysers7. The absence of methods specifically for rubber reflects the relatively small interest in the property in the industry. 

Coal analysis has, by convention, involved the use of wet analysis or the use of typical laboratory bench-scale apparatus. This trend continues and may continue for another decade or two. But the introduction of microprocessors and microcomputers in recent years has led to the development of a new generation of instruments for coal analysis as well as the necessary calibration of such instruments (ASTM D-5373). In particular, automated instrumentation has been introduced that can determine moisture, ash, volatile matter, carbon, hydrogen, nitrogen, sulfur, oxygen, and ash fusion temperatures in a fraction of the time required to complete most standard laboratory bench procedures. 

The volumetric marks on volumetric ware are called calibrations. How they were located on the volumetric ware is called calibration. All volumetric ware is calibrated to provide its stated volume at 20°C. The International Standards Organization has recommended that the standard volumetric temperature should be changed to 27 °C. However, so far there has not been any significant movement toward this goal. The ASTM recommends that those labs in temperate climates that are unable to maintain an environment at 20°C should maintain one at 27°C. 

Calorimetric methods are infrequently used for routine quality control purposes because of their non-specific nature and relatively slow speed. However, data from calorimetry experiments are commonly presented in applications for new product licenses and in support of patent applications. To ensure the integrity of all calorimetry data, normal procedures for good laboratory practices, standard operating procedures, appropriate calibration methods, and regular instrument servicing are necessary. The use of DSC for the measurement of transition temperatures and sample purity is described in the United States Pharmacopoeia, and standard procedures for DSC analyses are also suggested by the ASTM (100 Barr Harbor Dr., West Conshohocken, Pennsylvania 19428). 

Cut three specimens from the leather sample by the sampling method in Section 3.4.1. Each specimen consists of approximately 5 g of leather. Cut the specimen to small pieces of around 1 cm in diameter. Soak the specimen in a 250 ml flask with distilled water that is 20 times the weight of the specimen (ASTM D2810,2001b). Stopper the flask and shake thoroughly. Keep it in a conditioned room (temperature 23 1 °C) for 6 h. Remove the leather specimen from the flask and measure the pH of the solution with a pH meter that has been calibrated against standard pH solutions. Standard pH solutions (pH 4.0, pH 7.0 and pH 10.0) are conunercially available. 

The second method (ASTM D-4294, IP 477) uses energy-dispersive X-ray fluorescence spectroscopy, has slightly better repeatability and reproducibility than the high-temperature method, and is adaptable to field applications but can be affected by some commonly present interferences such as halides. In this method, the sample is placed in a beam emitted from an X-ray source. The resultant excited characteristic X radiation is measured, and the accumulated count is compared with counts from previously prepared calibration standard to obtain the sulfur concentration. Two groups of calibration standards are required to span the concentration range, one standard ranges from 0.015% to 0.1% w/w sulfur and the other from 0.1% to 5.0% w/w sulfur. 

The most common viscosity test is the kinematic viscosity method (ASTM D445, IP-71, DIN 51566 and ISO 3104). Note that lubricant viscosity is discussed in detail in the next chapter. The kinematic viscosity is the product of the time of flow and the calibration factor of the instrument. The test determines the kinematic viscosity of liquid lubricants by measuring the time taken for a specific volume of the liquid to flow through a calibrated glass capillary viscometer under specified driving head (gravity) and temperature conditions. The test is usually performed at a lubricant temperature of 40°C and/or 100°C to standardize the results obtained and allow comparison among different users. 

DTA measures the difference in temperature between the sample and a standard for the same rate of heat input. DSC compares the rate of heat inputs for the same rate of temperature rise. The latter is easier to analyze as it gives a direct measure of the rate of heat input. The method is based on the assumption that the samples are so small that thermal equilibrium is obtained almost immediately. For polymers this is not correct, and errors from this source are discussed by Strella and Erhardt [82]. Richadson [83 -86] and Laye [87] have discussed methods of calibrating the DSC to improve the accuracy of the results. The method is also outlined in ASTM El269 [88]. 

ASTM 3894 [139] is the standard that tests the flammability of the specimen arranged as two walls only, each 1220 mm x 610 mm high, or two walls plus a ceiling 1220 mm X 610 mm high, or two walls plus a ceiling 1220 mm square, which are exposed to a premixed propane flame positioned in the lower corner. A specified temperature time calibration is specified, and results are assessed in terms of flame spread. Thermocouples are positioned at specified locations on the specimen surface, and the times to maximum temperatures and the maximum temperatures are recorded. 

It is seen that the calibration constant disappears, which assumes that it is constant over the experimental conditions. The calculation is carried out using dedicated software. In some circumstances the crucible used for the sample may have to be different from that used for the calibrant. This means that a correction will be required to take into account the difference between the heat capacity of the two crucibles - readily calculated with sufficient accuracy. Measurements can be made at a series of temperatures but are meaningful only within the quasi-steady-state region of the experiment. The specific heat capacity of sapphire has been listed by ASTM in connection with the standard test method E 1269 (1999) for determining specific heat capacity by differential scanning calorimetry. 

Calorimetry is an absolute method of dosimetry, since almost all absorbed radiation energy is converted into heat that can be readily measured as a temperature rise of the calorimetric body. Calorimeters that are used as primary dosimeters do not require calibration and, ideally, their response is independent of dose rate, radiation characteristics, and environmental factors (Domen 1987). The calorimeters that are used in radiation processing for the measurement of absorbed dose are relatively simple and need calibration (ISO/ASTM 2003b). The use of calorimeters as primary standard dosimeters for electron beam irradiation is described by McEwen and Dusatuoy (2009) and for gamma irradiation by Seuntjens and Duane (2009). 

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