Equipment temperature calibration

Differential Scanning Calorimetry. DSC scans were made at 20°C min"1 on a Mettler TA300O system equipped with a DSC-30 low temperature module. Temperature calibration was done with a multiple Indium-lead-nickel standard. An indium standard was used for heat flow calibration. Thin shavings (ca. 0.5 mm thick) were cut with a razor blade from the cross-sectional edge of a plaque. These sections contained both surface and center portions. 

Many spectrometers are equipped with facilities to monitor and regulate the temperature within a probe head. Usually the sensor takes the form of a thermocouple whose tip is placed close to the sample in the gas flow used to provide temperature regulation. However, the readings provided by these systems may not reflect the true temperature of the sample unless they have been subject to appropriate calibration. One approach to such calibration is to measure a specific NMR parameter that has a known temperature dependence to provide a more direct reading of sample temperature. Whilst numerous possibilities have been proposed as reference materials [41], two have become accepted as the standard temperature calibration samples for solution spectroscopy. These are methanol for the range 175-310 K and 1,2-ethanediol (ethylene glycol) for 300-400 K. 

The DSC experiments were performed using a Perkin-Elmer Pyris-1 equipped with a cryofill. The purge gas was a mixture of 10 % helium and 90 % neon at a flow rate of 25 mL/min. The sample pans, which were supplied by v.d. Boel Eng. NL, had a volume of 40 xL, The temperature calibration of the analyzer was performed with the aid of adamantane, water, indium, and lead. The sample weight was in the range of 10 to 20 mg. The samples were kept for 20 min at -150 °C before being heated at a rate of 20 °C/min. 

Differential scanning calorimetry (DSC) investigations were performed on a Perkin-Elmer DSC-2 apparatus equipped with scanning autozero. Polymer samples and inserts (8-10 mg) and equivalent amounts of pilocarpine salts (ca. 1.0 mg) were analyzed at heating-cooling rates of 20 /min under dry nitrogen flow. Indium standards were employed for temperature calibration and enthalpy change evaluation. 

Temperature Calibration. As mentioned, temperature control and calibration of TGA equipment is more difficult. Not only are the sample and the thermocouple a finite distance apart, so as not to interfere with the weight measurement, but also the heat transfer between sample and oven in TGA is usually across an air or an inert gas gap. In addition, sample masses are often larger than those in DTA/DSC. There may be a large temperature gradient inside the sample. There are also other factors noted in the right-hand side of Table 5 that would affect temperature control. 

Typical field equipment subject to these requirements include weather stations or other weather collection equipment, temperature probes, freezers, balances, and application equipment (i.e., sprayer booms). Application equipment must be calibrated prior to its use in a GLP study, at the rate(s) to be used in the study. All calculations used in the calibration of the application equipment must be retained as raw data. 

This short sununary leads to the conclusion that the mass axis, customarily drawn as the ordinate, is much better defined than the temperature abscissa. As in DTA, careful calibration of temperature is necessary. The most reliable should be a temperature calibration within the equipment under conditions close to the actual measurement conditions. 

These temperature calibration materials are supplied by instrument manufacturers on request. The essential condition is that the material should be pure. The above data are generally available for determination of temperature on DTA or DSC equipment. 

Differential scanning calorimetry (DSC) of PET and its nanocomposites was performed on a Perkin-Elmer DSC 7 thermal analysis system on typically 7 mg of material at a scanning speed of 10°C/min from room temperature to the melting point of the PET. Before evaluation, the thermal runs were subtracted similar runs of an empty pan. The DSC equipment was calibrated using indium as a standard. 

The furnace and thermostatic mortar. For heating the tube packing, a small electric furnace N has been found to be more satisfactory than a row of gas burners. The type used consists of a silica tube (I s cm. in diameter and 25 cm. long) wound with nichrome wire and contained in an asbestos cylinder, the annular space being lagged the ends of the asbestos cylinder being closed by asbestos semi-circles built round the porcelain furnace tube. The furnace is controlled by a Simmerstat that has been calibrated at 680 against a bimetal pyrometer, and the furnace temperature is checked by this method from time to time. The furnace is equipped with a small steel bar attached to the asbestos and is thus mounted on an ordinary laboratory stand the Simmerstat may then be placed immediately underneath it on the baseplate of this stand, or alternatively the furnace may be built on to the top of the Simmerstat box. 

A pH electrode is normally standardized using two buffers one near a pH of 7 and one that is more acidic or basic depending on the sample s expected pH. The pH electrode is immersed in the first buffer, and the standardize or calibrate control is adjusted until the meter reads the correct pH. The electrode is placed in the second buffer, and the slope or temperature control is adjusted to the-buffer s pH. Some pH meters are equipped with a temperature compensation feature, allowing the pH meter to correct the measured pH for any change in temperature. In this case a thermistor is placed in the sample and connected to the pH meter. The temperature control is set to the solution s temperature, and the pH meter is calibrated using the calibrate and slope controls. If a change in the sample s temperature is indicated by the thermistor, the pH meter adjusts the slope of the calibration based on an assumed Nerstian response of 2.303RT/F. 

Moisture measurements are important in the process industries because moisture can foul products, poison reactions, damage equipment, or cause explosions. Moisture measurements include both absolute-moisture methods and relative-humidity methods. The absolute methods are those that provide a primaiy output that can be directly calibrated in terms of dew-point temperature, molar concentration, or weight concentration. Loss of weight on heating is the most familiar of these methods. The relative-humidity methods are those that provide a primaiy output that can be more direc tly calibrated in terms of percentage of saturation of moisture. 

Muffle furnaces. An electrically heated furnace of muffle form should be available in every well-equipped laboratory. The maximum temperature should be about 1200 °C. If possible, a thermocouple and indicating pyrometer should be provided otherwise the ammeter in the circuit should be calibrated, and a chart constructed showing ammeter and corresponding temperature readings. Gas-heated muffle furnaces are marketed these may give temperatures up to about 1200 °C. 

This study presents kinetic data obtained with a microreactor set-up both at atmospheric pressure and at high pressures up to 50 bar as a function of temperature and of the partial pressures from which power-law expressions and apparent activation energies are derived. An additional microreactor set-up equipped with a calibrated mass spectrometer was used for the isotopic exchange reaction (DER) N2 + N2 = 2 N2 and the transient kinetic experiments. The transient experiments comprised the temperature-programmed desorption (TPD) of N2 and H2. Furthermore, the interaction of N2 with Ru surfaces was monitored by means of temperature-programmed adsorption (TPA) using a dilute mixture of N2 in He. The kinetic data set is intended to serve as basis for a detailed microkinetic analysis of NH3 synthesis kinetics [10] following the concepts by Dumesic et al. [11]. 

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