Steam vortex flowmeter measurement is divided into saturated steam and superheated steam, relatively, vortex flowmeter manufacturers will give saturated and superheated steam quality flow range selection, it is convenient to determine the size of. Vortex flowmeter on the true meaning of saturated steam as long as the temperature and pressure compensation is good, in the measurement can be based on the temperature and pressure to check the density meter can be found out the required mass flow. Flow meter in the actual survey because of the changes of working conditions, saturated steam and superheated steam is likely to deviate from the original design of the state, usually by the steam temperature and pressure to calculate the density of the relationship in the change, will also affect the measurement accuracy.

The flow totalizer can draw density and calculated the mass flow rate based on pressure and temperature of superheated steam, but when the superheated steam through the long distance transportation or because the pipeline insulation measures properly, often because the heat loss temperature will decrease to make it enter from overheating state to the saturated state. In the condensation of steam there is a phase transition and become a drop of water, this time will become wet saturated steam. Vortex flowmeter output is only a fluid flow rate and flow through the pipeline measurement as its measurement is directly proportional to it in wet saturated steam, the dripping water will affect the vortex flowmeter output, can also be considered the output of vortex flowmeter is caused by wet saturated steam saturation, and in its density according to the temperature compensation or to precisely calculate the pressure compensation.

When the vortex flowmeter is installed in the valve back, wet saturated steam will suddenly have a substantial expansion of the fluid pressure, water evaporation, or from the liquid and vapor phase to absorb the heat of vaporization, the vapor-liquid temperature decreases, if the temperature is not reduced or evaporation of high humidity this will make the temperature rapidly decreased to the saturation temperature corresponding to the new pressure, a new equilibrium condition. The steam is saturated steam at this time of the case, if the pressure is reduced or steam humidity is low, this is because the stability of droplet evaporation is reduced, is still higher than the saturation temperature corresponding to the new pressure is changed into steam, superheated steam conditions.