Mass Flow Measurement

 


What is mass flow measurement


Mass flow meter measures flow rate of the fluid through the pipe. Mass flow meter does not measure the volume. The mass flow rate is the mass of fluid that passes by a fixed point per unit of time. Mass of the fluid can be determine by using this type of flow meter. By measuring the density of fluid this flow meter measures the mass. 

The Mass flow is proportional to density, cross-sectional area through which the substance is flowing, and velocity of fluid. This mass flow meter is very accurate and it is used to measure the flow of gases and fluids. 

Types of mass flow meter


What are the types of mass flow meter 
How mass flow meter work

Coriolis and thermal flow meters are two types of a mass flow meter. A mass flow meter is required for the accurate measurement of the mass related processes such as chemical reaction, heat transfer .

Thermal flow meter

In thermal flow meter a thermostat is used to measures the mass of the fluid flowing in the process, Thermister is inserted in the line in which fluid is flowing, this thermistor is used to neasure temperature. Sofluid is not clogged and thermal flow meter can also measure very low flow rates. 

Thermal flow meter working principle is based on thermal conductivity. Thermal flow meter will introduce heat into the flow stream and it measures the heat dissipation amount in flow stream. This flow meter don't dependent on the density, pressure, or viscosity of the fluid flowing in the stream.

Thermal flow meter can be used to measure the mass flow rate of fluids as well as flow of gases. Basically a thermistor is mounted inside the pipe of flow stream when the fluid passes through it carries the heat away from the thermistor. So when flow rate is high then the thermistor will become cool fastly and increases its resistance. Another thermister is installed in some accurate meters.

Types of thermal mass flow meter
Constant temperature difference

Two temperature sensorsa are used in this type of flow meter one is a heated sensor and other is to measure the gas temperature. Electrical power vonsumed to maintain the temperature difference between two sensors is proportiobal to mass flow rate.


How to install a thermal mass flow meter

 1. It must not be installed where the flow is downward in a vertical pipe.

2. Flow meter should be installed in a way that, it must be full of liquid so no air be trapped inside the tube.

 Advantages of thermal mass flow meter

1. Mass flow directly measures the flow without using pressure and temperature inputs. 
2. This type of flow meter give accurate measurement at very low flow rates. 

3. Pressure drop is less in mass flow meter. 

4. This ttpe of fliw meter is less costly. 
5. This type of flow meter is Maintenance free
6. There is no need for pressure and temperature compensation. 

7. Its installation is easy. 


Applications of thermal mass flow meter

Oil and gas
Power plants
Chemical plants
Water and waste
Metals and mining process
Food and beverage
Pharmaceuticals
Textile industry


Coriolis meter

Corolios mass flow meter is U shaped and it is used to measure fliw of gases and liquids. The fluid will flow through a U shaped tube and tube vibrates and this vibration will be proportional to the fluid flow. Energy and velocity of the fluid resists the vibrating motion of the tube, and that makes it twist sideways. The degree of deflection is linearly and directly proportional to the mass of the fluid that passes through the tube. Magnetic position sensors are used to measure the amount of twist in the tube. 

Advanatage of corolios flow meter is high accuracy. 





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