Orifice flowmeter has a longer history in the industrial production instrument panel, and it is a more common flowmeter with simple structure, convenient manufacture, easy installation, application, maintenance and other simple and easy to understand.Very high credibility.Only according to the national industry standards to carry out the calculation, production and processing, the foundation does not need real flow calibration, can immediately get higher accurate measurement accuracy.In recent years, the types of flowmeters have become more diverse, but orifice flowmeters can still maintain a certain market share.It shows that orifice flowmeter can not be substituted.The orifice flowmeter measures the initial value as differential pressure, which is proportional to the hydrodynamic flow after the square root.Orifice flowmeter flow detection range by differential pressure value, discharge index, Reynolds number and other factors of harm, promote orifice flowmeter range ratio can not be increased, the following simple analysis of orifice flowmeter range ratio is limited key reasons.
Orifice flowmeter range ratio is 5:1, the number is not more than 10:1, the first is the range of differential pressure transmitter.Differential pressure transmitter is a more precise component of orifice flowmeter.The measuring range of differential pressure transmitter and its accurate measuring precision immediately determine the accurate measuring precision and measuring range of orifice flowmeter.In the calculation formula of orifice flow, the differential pressure is proportional to the square meter of flow.It is not difficult to see that if the application flow is 30% of the full range, the differential pressure value is 9% of the full range of the differential pressure transmitter.
If the flow rate is 20% of the full flow rate, then the differential pressure value is 4% of the full range of the gas pressure differential pressure transmitter.According to the uncertainty calculation method in gb/t1624-93, when the field application flow is less than 10% of the full flow, the uncertainty is too large.Therefore, the manufacturer proposed that the orifice flowmeter range ratio should not exceed 10:1;The second factor of containment is the containment of the discharge index.The orifice flow formula calculation will discharge index as a constant, but under certain installation standards, discharge index is changes with the Reynolds number, thus made in the concrete process in general will expand the orifice differential pressure flowmeter lower limit value and ascension to reduce discharge index of the dangers of accurate measurement of orifice flowmeter.This method increases the range ratio of orifice flowmeter.The third is the restriction of the coefficient of thermal expansion.The coefficient of thermal expansion is the change of discharge index caused by the change of relative density of convective physical energy by the throttle valve.Under the common flow standard, the coefficient of thermal expansion is close to 1. If excessive deviation of common flow is applied on the spot, additional deviation will be caused.This point is the key reason to limit the orifice flowmeter range ratio.
Orifice flowmeter characteristics
1. Orifice flowmeter throttling device is easy to copy, simple, solid, stable and reliable, with long application period, good quality and low price.
2. Orifice plate measurement shall adopt national standards and production and processing
3. Orifice flowmeter has a wide coverage, all single-phase currents can be accurately measured, and part of miscible flow can also be used.
4. The basic throttling device can be put into use without real flow correction.
5. The all-in-one orifice flowmeter is easier to install without pressure tube, and can be connected to differential pressure transmitter and temperature transmitter immediately.
6. Imported monocrystalline silicon intelligent differential pressure sensor is selected
7. High precision, sound self-diagnosis function
8. Intelligent orifice flowmeter intelligent orifice flowmeter its measuring range can be programmed and adjusted by itself.
9. The intelligent orifice flowmeter can also display the total flow, instantaneous velocity flow, working pressure and temperature.
10. In addition to free online and dynamic full compensation, intelligent orifice flowmeter is also equipped with self-diagnosis and independent range setting.
11. Equipped with a variety of communication ports
12. High reliability
13. The range is wider than 10:1
14. High precision: ±0.075%
15. High reliability: better than 0.1%FS/ year
16. High negative pressure: 40MPa
17. No calibration is required for 5 years of continuous work
18, can ignore the temperature, negative pressure harm
19, resistance to high overpressure
At present, Shanghai porcelain flowmeter has been exported to more than 100 countries, involved in more than 100 industries.At the same time, the research and development of micro flowmeter also obtained the metrological certification.At home to fill the gap in the micro flowmeter, while breaking the monopoly of foreign enterprises.