What is the mass flow rate of gas. If we take the virtual cylinder with the volume 1 liter that is hermetically closed from the one side, and from the other one-it has the movable piston with the very small weight. Such a cylinder places 1 liter of air under normal condition almost 1 bar. The weight of this air volume is 1,293 grams under the condition that the temperature equals to 0C. If we will move the piston on the half-width to the cylinder bottom, then the volume of the air will be decreased twice.
It will be 0,5 liters, the pressure here will be 2 bars, but the weight won t change and it will be 1,293 grams. It is caused by that fact that the amount of the air molecules that are placed in the cylinder won t change.
If we will follow such an example then the mass flow rate should be measured in units per minute, such as gram per minute or milligram per second or others. We got used to think and to work with gases using volumetric units liters, cubed meters etc. Such a problem won t arise if we will discuss the conditions temperature and pressure, under which the volume is changed. In the case of such conditions the temperature 0C and the pressure 1,013 bars were chosen. So, the gas flow meters mass flowmeters, measure the gas flow expense in volumetric units per minute under normal conditions, separately from the real temperature of gas and its pressure in the measuring moment.
Other words, such a measurer defines the amount of molecules that pass through the device. It should be mentioned that the given in the guidance and technical descriptions variables of volumetric flows expenses corresponds to the normal conditions the temperature is equal to 0C and the pressure is equal to 1,013 bars. For example if we choose the base temperature not 0C, but 20C then the difference in calculations will be 7. ь Mass flowmeters.
In the practical use of gas expense there were such situations that it was better to measure it not in the volumetric but in the mass units. Due to this the actual heat content will be represented more accurate. Except this more accurate will be energy expense and matter quantity that goes to the supplier or on the technological process. Mass expense may be calculated by reverse and direct ways. In reverse flowmeters the combination of raft meter66 плотномер with volumetric flowmeter is used. The expense that is measured with the help of any volumetric flowmeter then it automatically multiplies on the measured environment density.
In the flowmeters of direct action, that is also called power, the expense is mined under the power moment, is created in the flow due to application of additional motion.