Home > Knowledge > Content

Flow meter accuracy

Dec 29, 2018

Flow meter accuracy

The accuracy level of the flow meter refers to the large allowable error expressed by the percentage of the meter minus the percent sign. The higher the accuracy, the lower the level and the smaller the error.

The performance of the general-purpose models on the market is quite different, some have high precision, many functions, some have low precision, and the functions are simple. The instrument accuracy with high accuracy is about (±0.5%~±1%) R, and the instrument with low precision is (±1.5%~±2.5%) FS. The difference between the two offers is 1~2 times. Therefore, it is economically uneconomical to select a high-precision appearance when the accuracy requirements are not high (for example, non-trade accounting is only for control purposes, and electromagnetic flowmeters only require high reliability and excellent repeatability).

Flow meter accuracy

Some instruments say that they have higher accuracy, the error is basically only (±0.2% ~ ±0.3%) R, but there are strict equipment requirements and reference conditions, such as ambient temperature 20 ~ 22 ° C, front and rear straight pipe length requirements More than 10D and 3D (usually 5D and 2D), respectively, even the flow sensor should be integrated with the front and rear straight tubes for real-flow calibration on the flow standard equipment to reduce the impact of the clamping. Therefore, do not simply look at high and high indicators when comparing multiple models.

The serial digital communication function of some models of instruments can be selected from a variety of communication interfaces and dedicated chips (ASIC), turbine flowmeter to connect HART protocol system, PROFTBUS, Modbus, CONFIG, FF field bus and so on. The condition for applying EMF is that the liquid to be tested needs to be electrically conductive and cannot be below the threshold (ie, the lower limit). If the conductivity is lower than the threshold, measurement errors or even unusable will occur. Even if the threshold is exceeded, the measurement can be measured, and the indication error does not change much. The threshold of the general-purpose EMF is between 10-4 and (5×10-6) S/cm. , depending on the model. In use, it also depends on the length of the flow signal line between the sensor and the converter and its distributed capacitance. The length of the signal line corresponding to the conductivity is generally specified in the manufacturer's instruction manual.

Flow meter accuracy

Specific analysis of the accuracy of the flowmeter:

       Calculation method: relative percentage error = (measured value of measured parameter - standard value of side parameter) / (scale upper limit - scale lower limit) * 100%

       Flowmeters on the market use different processes and therefore have different levels of accuracy. So how is the progress level of the flow meter divided? Huaheng Instrument Co., Ltd. makes the following analysis for you:

1. The accuracy of the first-class standard instrument is: 0.005, 0.02, 0.05

2. The accuracy of the secondary standard instrument is: 0.1, 0.2, 0.35, 0.5

3. The accuracy of general industrial instruments is: 1, 1.5, 2.5, 4.0

4. The accuracy level of instruments used in scientific experiments is above 0.05.

5. Electrical instruments are divided into seven levels of 0.1, 0.2, 0.5, 1.0, 1.5, 2.5, and 5.0.

      The accuracy of the general Coriolis mass flowmeter is 0.2, the accuracy of the turbine flowmeter is 0.5, the accuracy of the vortex flowmeter is 1.5, the accuracy of the target flowmeter is 1.0, the accuracy of the glass rotor is 2.5, and the flow of the metal tube float The meter is 2.5, and the electromagnetic flowmeter is 0.5.


Flow meter accuracy

   Huaheng Instrument ,well-known brand, professional selection, professional quotation, summed up the experience of production practice for many years, and strive to develop various flow metering products, according to the needs of different customers, different customer equipment requirements, professional custom Non-standard flowmeter products, in accordance with the parameters and requirements provided by customers, "customized" for customers, adhere to the "quality first, customer first" governance policy to ensure long-term product quality and continuous improvement, for Users provide quality products and perfect services.

You may be interested in what is a pressure transmitter.