Calibrated thermometer

The fixed reference points for ITS-90 (temperatures at specified equilibrium states) are given in Table A2.1. These reference points are selected to calibrate thermometers over different temperature ranges as we describe later. 

An NiCr heater (H) was glued onto the bottom end of the sample, and two Ru02 calibrated thermometers (for the measurement of Th and Tc ) were glued near the bottom end of the sample (see Fig. 11.6). 

Low-temperature thermometers are obtained by cutting a metallized wafer of NTD Ge into chips of small size (typically few mm3) and bonding the electrical contacts onto the metallized sides of the chip. These chips are seldom used as calibrated thermometers for temperatures below 30 mK, but find precious application as sensors for low-temperature bolometers [42,56], When the chips are used as thermometers, i.e. in quasi-steady applications, their heat capacity does not represent a problem. In dynamic applications and at very low temperatures T < 30 mK, the chip heat capacity, together with the carrier-to-phonon thermal conductance gc d, (Section 15.2.1.3), determines the rise time of the pulses of the bolometer. 

This last paragraph inevitably leads to the questions, So how do we know what the exact temperature is and How do I know if my thermometer follows profile (a) or profile (b) in Figure 1.4 Usually, we do not know the answer. If we had a single thermometer whose temperature was always accurate then we could use it as a primary standard, and would simply prepare a calibrated thermometer against which all others are calibrated. 

Viscosity depends on temperature. The higher the temperature, the lower the viscosity Pancake syrup, for example, flows more freely when heated. For reasonable accuracy when measuring viscosity, the temperature must be very carefully controlled. This means that the viscometer and sample must be immersed in a constant temperature bath and the temperature given time to equilibrate before the measurement is recorded. A calibrated thermometer must be used to measure the temperature. 

A thermocouple is a junction of two metals that produces a voltage proportional to temperature and is therefore a device for measuring temperature. A thermocouple can be calibrated with the use of known temperatures, such as the freezing point of water (slushy ice-water mixture) or temperatures known because they are measured with a calibrated thermometer. 

Several techniques are available for thermal conductivity measurements, in the steady state technique a steady state thermal gradient is established with a known heat source and efficient heat sink. Since heat losses accompany this non-equilibrium measurement the thermal gradient is kept small and thus carefully calibrated thermometers and heat source must be used. A differential thermocouple technique and ac methods have been used. Wire connections to the sample can represent a perturbation to the measurement. Techniques with pulsed heat sources (including laser pulses) have been used in these cases the dynamic response interpretation is more complicated. 

As the difference between refractive indices of NG and EGDN is fairly large, Rinkenbach decided to apply this difference to analysis of EGDN—NG mixtures. He used a precision Leitz xeftactometer, equipped with a water jacket and calibrated thermometer. Indices were derd over a wide range of temps for each substance previously... 

Calibrated thermometer with range above 100°C Water bath with temperature range to 100°C... 

The temperature accuracy of the column heater is evaluated by placing a calibrated thermometer in the column compartment to measure the actual compartment temperature. The thermometer readings are compared to the preset temperature at 40 and 60°C. Many LC equipment manufacturers have the requirement set at 2°C. The temperature stability of the column compartment can be assessed indirectly by comparing the retention time of certain peaks in the chromatogram over time. Acceptance criteria of the stability evaluation should be assessed on a case-by-case basis due to different laboratory conditions and environment. 

The drying temperature and drying time are traceable to the SI through calibrated thermometer and calibrated clock. 

NIST-calibrated thermometers are expensive, but very accurate tools. Unfortunately, they require special use and maintenance to maintain their integrity. Not only can abuse alter their calibration, but general use can as well. For example, if you are using an NIST-calibrated liquid-in-glass thermometer on a regular basis, an ice-point recalibration should be taken after each measurement. These variations should be added to the adjustments made to the corrected scale temperatures. 

Measuremaits. A thermostat bath containing water or glycerine (at temperatures above 95 °C) was used in the melting point determinations. The temperature was regulated to 0.02 C. A calibrated thermometer was used. The melting point was taken as the temperature at which the last crystals of solid became liquid or at which turbidity cleared. 

For most purposes, it is convenient to use partial-immersion thermometers, because the corrections required at any temperature will usually be smaller. However, regardless of which type is used, it should be calibrated against some thermometers for which the calibrations are known. The common practice of calibrating thermometers by using the melting points of known substances will often lead to considerable errors if the capillary method is used. 

With all three phases present, none of the physical conditions can be varied without the loss of one phase. As a corollary, if the three phases are present, the temperature, the specific volume, and so on, must always be fixed at the same values. This phenomenon is useful in calibrating thermometers and other instruments. 

Heat the shaking water bath to 39°C. Check temperature using a calibrated thermometer. Prewarm the hybridization buffer in a 37°C water bath. Mix from time to time to dissolve the crystals that could be present. Do not proceed unless all crystals are dissolved. 

Primary standards are those developed and maintained by national standards laboratories such as the National Bureau of Standards. These laboratories develop, maintain, and disseminate standards, such as the International Practical Temperature Scale. The IPTS-68 is disseminated to the users through secondary standards such as calibrated thermometers, fixed point references, and so on (see Table II). Some of these thermometers are calibrated directly against the defining fixed points and others are calibrated over the range of need by a comparison calibration against a standard interpolating thermometer. This ensures that the basis for temperature measurement, the IPTS-68, is the same everywhere throughout the world. 

Calibrated thermometers - if your compound is only slightly impure and has a melting point 2 C lower than the literature value, a thermometer reading 10 C low will give you an error of 12 C, indicating a low level of purity and hence a low grade or false information to fellow scientists. 

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. 

Instruments, apparatus, gages and recording devices shall be calibrated at predetermined intervals in accordance with good scientific practices and instructions from the manufacturers. Balances and scales, and weights for these, shall be calibrated at least every year. Calibrated thermometers shall be employed for practice temperature measurements. 

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