A fluid quality, unit volume of fluid known as the quality of density, to P said. In any point in the flow from a small-size ^ V, the volume contains the fluid quality of ^ m, while its density is between both P = ^ M / ^ V. any point of its density, can take the limit by:

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Countdown known as the density of specific volume, with symbols v-table, the unit is the quality of the fluid volume

When the fluid is tested liquid, if it's clear components, and is commonly used medium, its density from the manual to obtain. If the use of methods for measuring density, temperature should be obtained under the density value, If the temperature changes in the scope of 20 , the density and temperature is basically a linear relationship, it may be two different temperatures by measuring the density, temperature and density to make a linear relationship, and then obtained within the scope of arbitrary Temperature points on the medium density.

For gas, excluding gas molecules of the interaction between itself and molecular size, that is, that is the ideal gas, its density P, temperature T, P pressure between the use of its equation of state said relations.

P ^ 112

Where, R as a gas constant, in units of J / kg.mol.K.

As for the majority of the tested gas mixture, the density of these gases to be adopted after the analysis of gas composition ratio obtained. Components of the density of the gases may generally be accessible through the manual. If others know of various components of the volume ratio, Hybrid gas density ^ n may be under-calculation:

^ 113

In the formula ^ niDDI category gas composition in the density of state standards;

XiDDa kind of the i element of the volume ratio gas

if the standard under the density ^ n, in other states, that is absolute temperature T, is under pressure P P medium density may be under-win:

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In the formula TnPnUnder the absolute standard temperature (273.15 K) to the absolute pressure (101 325.024Pa);

KnKDDUnder the standard approval status and the general state of the compression factor in the low pressure, the assumption that the establishment of the ideal gas within the compression factor of 1.

Table 1-1 in a several common standards under state gas compression factor Kn value.