Thermal gauge

Medium vacuum (25-1 x 10 Torr) is vacuum that can be achieved with a single pump, but the pressure cannot be measured by liquid or mechanical manometer. The pressure can be measured with a thermal gauge or a capacitive gauge. 

Vacuum gauges may be broadly classified as either direct or indirect (10). Direct gauges measure pressure as force pet unit area. Indirect gauges measure a physical property, such as thermal conductivity or ionisation potential, known to change in a predictable manner with the molecular density of the gas. 

Experimental screening involves conducting experimental tests to gauge the thermal hazard of materials and processes. The goal of these tests is to provide information by which the materials and processes may be characterized. Experimental screening can be performed for the following ... 

Gauge pressure of a space The positive or negative pressure in a space with respect to its surroundings, due to wind or thermal forces or the relationship of supply air to extract air. 

Fig. 2. A schematic variation of the thermal expansion, reduced to the gauge length 1, for the components of the composite (f corresponds to the elastic filler, m to the matrix, i to the mesophase and, c to the composite). The (Al/IJ of the composite is chaneing slope twice, at Tg, and Tgm. The Tgc is found approximately by the intersection of the two external linear branches of the (Al/lc) = f(T) curve...

Vessels normally have a relief device to prevent damage during thermal expansion. A stainless steel cylindrical vessel has 1/4-in thick walls and is 4 ft in diameter. It is filled with 400 gal of water, and 0.2 ft3 of air is trapped at a pressure gauge. Start at 0 psig and 50°F and then heat the vessel. At what temperature will this vessel rupture if it does not have a relief ... 

Apart from the qualitative observations made previously about suitable solvents for study, the subject of solvates has two important bearings on the topics of thermochemistry which form the main body of this review. The first is that measured solubilities relate to the appropriate hydrate in equilibrium with the saturated solution, rather than to the anhydrous halide. Obviously, therefore, any estimate of enthalpy of solution from temperature dependence of solubility will refer to the appropriate solvate. The second area of relevance is to halide-solvent bonding strengths. These may be gauged to some extent from differential thermal analysis (DTA), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) solvates of "aprotic solvents such as pyridine, tetrahydrofuran, and acetonitrile will give clearer pictures here than solvates of "protic solvents such as water or alcohols. 

Figure 1. Schematic representation of the calcium mass spectrum in (a) natural materials, (b) a Ca- Ca tracer solution used for separating natural mass dependent isotopic fractionation from mass discrimination caused by thermal ionization, and (c) a typical mixture of natiwal calcium and tocer calcium used for analysis. The tracer solution has roughly equal amounts of Ca and Ca. In (c) the relative isotopic abundances are shown with an expanded scale. Note that in the mixed sample, masses 42 and 48 are predominantly from the tracer solution, and masses 40 and 44 are almost entirely from natural calcium. This situation enables the instrumental fractionation to be gauged from the Ca/ Ca ratio, and the natural fractionation to be gauged from the sample Ca/ Ca ratio.

An appropriate cure cycle was established based on the results obtained from the thermal analysis and cure rheology studies of the resin and cured BCB bar and dogbone shaped samples were fabricated for testing. Bar shaped specimens had the dimensions of 3.5 x 0.5 X 0.125 and were used to stake compact tension specimens for fracture toughness studies and for dynamic mechanical analysis of a torsion bar. Dogbone shaped specimens for tensile tests had a gauge area of 1 x 0.15 and were approximately 0.040 thick. 

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