Temperature sensing calibration

Temperature Recording. Use an accurate temperature-sensing device, such as a clinical thermometer or thermistor or similar probe, that has been calibrated to ensure an accuracy of 0.1° and has been tested to determine that a maximum reading is reached in less than 5 min. Insert the temperature-sensing probe into the rectum of the test rabbit to a depth of not less than 7.5 cm and, after a period of time not less than that previously determined as sufficient, record the rabbit s temperature. 

The National Institutes of Standards and Technology (NIST, formerly the National Bureau of Standards (40)] sells a high-purity gallium standard in a Teflon and nylon container [Standard Reference Material (SRM) no. 1968] for use as a temperature standard. The melting point is 29.7 70 C and can be used to calibrate thermometers and other temperature-sensing devices. 

Modem automated thermometric titrators consist of a constant delivery pump for the titrant, a temperature control system for the titrant, an insulated cell, calibration circuitry, electronic temperature sensing, and a data processing system. Most modem instruments are totally computerized, so different methods can be programmed and run unattended. 

Thermoelectric flow sensors indirectly measure the velocity of gases and liquids close to the wall and the volume flow rate in a microchannel. Electrical heating, thermoelectric temperature sensing, appropriate calibration, and... 

The preceding presentation on temperature measurement shows clearly how complex the subject is and what precautions must be taken to obtain a meaningfiil temperature measurement. The proper use of the right temperature-measxuing instruments is very important. Calibration for instrumental errors is mandatory for temperature-sensing devices and other temperature-measurement-system components periodic checking of the calibration is also very important. 

The Rule of 10 is better still. If we use 10 times the number of samples as there are components, we will usually be able to create a solid calibration for typical applications. Employing the Rule of 10 will quickly sensitize us to the need we discussed earlier of Educating the Managers. Many managers will balk at the time and money required to assemble 40 calibration samples (considering the example, above, where temperature variations act like a 4th component) in order to generate a calibration for a "simple" 3 constituent system. They would consider 40 samples to be overkill. But, if we want to reap the benefits that these techniques can offer us, 40 samples is not overkill in any sense of the word. 

It is clear from the Nemst equation that the temperature of the solution affects the response slope (2.303A7//0 of the calibration curve. The electrode voltage changes linearly in relationship to changes in temperature at a given pH therefore, the pH of any solution is a function of its temperature. For example, the electrode response slope increases from 59.2mV/pH at 25°C to 61.5 mV/pH at a body temperature of 37°C. For modem pH sensing systems, a temperature probe is normally combined with the pH electrode. The pH meter with an automatic temperature compensation (ATC) function automatically corrects the pH value based on the temperature of the solution detected with the temperature probe. 

Here functions Qnt X), Qj(X), and QP(X) can be determined experimentally using calibration samples. If these functions are linear independent then the parameters Ank, A, and Ap can be uniquely determined from the variation of P /1, , n2,. .. /( . /. / considered as a function of X. In particular, the side effects, i.e., the temperature and pressure dependences, can be eliminated from the transmission spectrum. The sensing method based on this simple idea was applied in Ref. 69 for determination of microfluidic refractive index changes in two microcapillaries coupled to a single MNF illustrated in Fig. 13.26c. The developed approach allowed to compensate the side temperature and pressure variation effects. 

In a kinetic sense, the system is a better solvent than HFIP alone. We postulate that MeCl2 swells the amorphous regions of PET thereby providing HFIP with an easy access to the crystalline regions. This swelling action does not occur with HFIP alone, and the dissolution process takes much longer. At room temperature, amorphous PET is Instantaneously solubilized by this solvent system. PET that has been annealed for >24 hr at 220 C to yield maximum crystallinity dissolves in <4 hr at room temperature. PET annealed in this manner does not dissolve in pure HFIP after 14 days at room temperature. Poly(butylene terephthalate) and aliphatic polyamides are soluble in this solvent system. Polystyrene is also soluble, which permits conventional calibration and the use of the universal calibration approach. We have determined the Mark-Houwlnk relationships for PET and polystyrene in 70/30 MeCl2/HFIP to be... 

The emf developed by a thermocouple depends upon the temperature of both the measuring and reference junctions. Thus, to determine temperature, the following data musi be known (1) the calibration data for the particular thermocouple (2) the measured emf and (3) the temperature of the reference junction. In laboratoiy cases, the reference junction can be maintained at the freezing temperature of water. However, in most modem instruments, the ambient temperature of the reference junction is sensed, and the correction is incorporated in the measurement circuitry. 

As a result, it was found that NIR had the same accuracy as the conventional method when using individual calibration for each variety. To design an on-line NIR sensor, the effects of sample temperature, moisture, air bubbles, and shape of flow cell were simulated. Based on the these results, an on-line sensing system has been developed. 

Because each enzyme sensor has its own unique response, it is necessary to construct the calibration curve for each sensor separately. In other words, there is no general theoretical response relationship, in the same sense as the Nernst equation is. As always, the best way to reduce interferences is to use two sensors and measure them differentially. Thus, it is possible to prepare two identical enzyme sensors and either omit or deactivate the enzyme in one of them. This sensor then acts as a reference. If the calibration curve is constructed by plotting the difference of the two outputs as the function of concentration of the substrate, the effects of variations in the composition of the sample as well as temperature and light variations can be substantially reduced. Examples of potentiometric enzyme electrodes are listed in Table 6.5. 

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