A thermal gas mass flow meter is a unique gas mass measurement meter; its principle is based on the principle of thermal diffusion. It is designed using the constant temperature difference method. It is widely used in petroleum, new energy, environmental protection, electric power, pharmaceutical, chemical, light, and other industries.
Ground pipeline in situ meter head display, high-altitude pipeline split meter head display, but not all occasions apply to the thermal gas mass flowmeter. Therefore, before choosing the flowmeter, we need to confirm whether the site of some technical parameters is in line with the applicable thermal gas mass flowmeter.
1. Features of thermal gas mass flowmeters
The thermal gas mass flowmeter is a gas measuring instrument with many advantages and various forms.
1.1 It has a wide range ratio, slight pressure loss, and high accuracy.
1.2 It can directly measure the standard gas flow without temperature and pressure compensation and other features that other flow meters do not have.
1.3 Its power supply is also diverse (24V and 220V).
2. The medium of the thermal gas mass flow meter
The thermal gas mass flow meter measures the gas mass flowmeter instrument. It can measure almost all single gas media (only acetylene can not be measured).
However, some of the actual measurement sites will have mixed gases that need to be measured. Choosing the thermal gas mass flow meter will have specific requirements for mixed gases because all gas flow meter calibration is used with air as the measured medium. In a single medium is possible to find out the standard conversion factor.
But mixed gas needs to be converted to coefficients based on the percentage of the composition of the measured medium on site. So when we are measuring, the media composition will change. Then it will increase the measurement error of the flowmeter, so we are in the selection, the measurement medium should also be calibrated in detail.
3. The pressure of the thermal gas mass flow meter
The thermal gas mass flow meter is generally suitable for medium pressure is 4.0MPa. Because the hot gas mass flow meter medium is usually high heat content.
When the site pressure is too high, the unit volume of the medium with too much heat in the compression system reflects the rate of the two influences, making the instrument’s measurement value less than the actual value used. So the thermal gas mass flowmeter in the selection stage of the site pressure should also be standardized in place.
4. The flow rate of thermal gas mass flowmeter
The flow rate of JC010 should be expressed in terms of mass flow per unit time. However, it is customary to calculate the volume per unit time flowed in the normal state when measuring gases. Therefore, the flow rate is also expressed as the distance flow length per unit time in the standard condition.
JC010 is suitable for low flow ranges compared to other flow meters, especially for small diameter heat distribution types. Measuring short tube immersion detection rod type optional upper limit (total) flow rate range is wide, the upper range degree (maximum upper flow rate / minimum upper flow rate) in 10 ~ 30 and 60 ~ 80.
Insertion type thermal gas mass flowmeter upper limit flow rate selection range is more expansive, can be in 0.5 ~ 100m / s, but more for 3 ~ 60m / s between, depending on the instrument structure design and different—insertion type T thermal gas mass flowmeter for low flow rate flue gas measurement.
The upper limit of the mass flowmeter for liquids is minimal, the upper limit of foreign products in the range of 10-1 to 102g / min between the order of magnitude, and the flow range between 10:1 to 50:1.
5. The pipe size of the thermal gas mass flowmeter
Gas mass flowmeter scale selection has a more significant impact on its accuracy and service life, and each caliber of flowmeter has a specific measurement scale.
The flow scale also determines the selection of flowmeter caliber. The principle of selecting the flow scale is: that the use of the minimum flow rate shall not be lower than the minimum flow rate of the appearance of the promised measurement. Likewise, the application’s maximum flow rate shall not be higher than the maximum flow rate of the formation of the promised size.
For continuous work where the actual operating time of the exterior does not exceed 8 hours per day. Select 1.3 times the maximum flow rate in practice as the upper limit of the flow rate scale; for the continuous operation of the daily appearance in preparation for not less than 8 hours.
Select 1.4 times the maximum flow rate in practice as the upper limit of the flow rate scale. The lower limit flow rate of the external surface is 0.8 times the minimum flow rate in the course.
6. Note
In addition, the user side of the thermal gas mass flowmeter should pay special attention to the need to provide complete as possible the working conditions data and some technical requirements. Flow range, measuring medium, pipe diameter, pipe material, working pressure, working temperature, working environment temperature, signal power requirements, accuracy level, and other important parameters unless you choose some fixed models of thermal gas mass flowmeter, we can not provide the above technical parameters directly with the manufacturer to dock the specific model.
7. Conclusion
The thermal gas mass flow meter is easy to install, easy to maintain, anti-vibration, and has a wide range ratio (100:1). As a result, large-diameter small flow measurement and other advantages are widely used in chlorine, ammonia, gas, compressed air, hydrogen, nitrogen, and multi-component gas measurement.