主要是看中其高精确度，但是流量计准确度愈高，对现场使用条件的变化就愈敏感，所以，对仪表精确度的选择要慎重，应从经济角度考虑。 1. Accuracy level: Generally speaking, the choice of turbine flowmeter is mainly for its high accuracy, but the higher the accuracy of the flowmeter, the more sensitive it is to changes in field conditions. Therefore, the accuracy of the meter must be selected. Prudence should be considered from an economic perspective.
For the trade settlement instruments of large-diameter gas pipelines, it is cost-effective to invest more in the instruments, and for the occasions where the transportation volume is not large, it is only necessary to choose a medium accuracy level.
2. Flow range: The selection of the flow range of the turbine flow meter has a greater impact on its accuracy and service life. Also, each type of flowmeter has a certain measurement range. The selection of the flowmeter diameter is also determined by the flow range. .
The principle of selecting the flow range is: the minimum flow rate in use must not be lower than the minimum flow rate allowed by the meter, and the maximum flow rate in use must not be higher than the maximum flow rate allowed by the meter. For intermittent working occasions where the actual running time of the meter does not exceed 8 hours,
Select 1.3 times the maximum flow rate in actual use as the upper limit of the flow range; for continuous working occasions where the actual operating time of the meter is not less than 8 hours, select 1.4 times the maximum flow rate in actual use as the upper limit of the flow range. The lower limit of the meter is based on the actual
It is appropriate to use 0.8 times the minimum flow.
，流体物性的影响主要是气体密度，它对仪表系数的影响较大，且主要在低流量区域。 3. Density of gas : The effect on the gas turbine flowmeter and fluid physical properties is mainly the density of gas, which has a greater impact on the meter coefficient, and is mainly in the low flow area. If the gas density changes frequently, corrective measures should be taken for the flow coefficient of the flowmeter.
4. Pressure loss: Try to choose a turbine flowmeter with a small pressure loss. Because the smaller the pressure loss of the fluid through the turbine flowmeter, the less energy the fluid consumes from the input to the output pipeline, that is, the total power required will be reduced, which can greatly save energy,
Reduce transportation costs and increase utilization.
Some people have done experiments. The main component that affects pressure loss is the front deflector of the turbine flow meter. Compared with the front deflector of the cone, the front deflector of the semi-ellipsoid is used. Can be greatly reduced.
5. Structural type: The internal structure should use reverse push-type turbine flowmeter. Because the reverse push structure can make the impeller float in a certain flow range, there is no contact point in the axial direction, there is no end face friction and wear, and the service life of the bearing can be extended.
Models are selected according to the pipeline connection method. There are two types of horizontal and vertical installation of the flow meter. The flange connection, screw connection and clamp connection are available for horizontal installation and pipeline connection. Medium diameter is selected by flange connection; small diameter and high pressure pipeline is selected by thread connection
Clamping connection is only suitable for low pressure medium and small pipe diameter; vertical installation only has screw connection. (3) Select according to the environmental conditions, and consider the influence of temperature and humidity. Natural gas measurement should choose intrinsically safe explosion-proof turbine flowmeter.
6. Bearings: The bearings of turbine flowmeters are generally made of tungsten carbide, polytetrafluoroethylene and carbon graphite. Natural gas metering instrument bearings should use tungsten carbide materials.
These are the main aspects to consider when selecting a model. 类型规格繁多，特别是不同的制造厂产品质量有差别，选型时应尽量搜集制造厂及产品的有关技术标准等资料，进行反复调查比较后再决定取舍。 Because there are many types and specifications of turbine flowmeters , especially the quality of products from different manufacturers, you should try to collect the relevant technical standards of the manufacturer and the product when selecting models. After repeated investigations and comparisons, you can decide to choose.