Differential pressure flow transmitter is one of the combination instruments with pneumatic instrument and electrical unit and usually used with standard orifice plate. It is an important instrument widely used by the industrial enterprises for energy measurement and trading settlement. Generally, the flow transmitter is calibrated by maintenance and verification personnel on site. During calibration, the flow value will be converted into differential pressure value. To calibrate a differential pressure flow transmitter, complicated calculation is required before the standard signal input...
The essay herein analyses and compares the mainly existing problems for the measurement of the air flow that is of lower velocity and in large diameter duct. Through the wind tunnel test, the research is emphasized on the characteristics and mathematical model of the insert double ventrui tube and describes the structure, composition, erection, specialties and application of such tube and its advantages when applied in the measurement and control of assistant combustion air, cool air and coal air (blast furnace coal air, cokery coal air and converter coal air) of the heating furnaces in...
The secant method for solving nonlinear equation is used to calculate the unknown parameters of pressure differential devices. It is shown that the important advantages are needing only unique iterative equation without considering different unknows, easily to obtain convergent solutions without to calculate the derivatives which can not be finished for complex nonlinear equation, and yielding high precision solutions. The formulae of initial values and the example for showing the results are presented, the results are excellent.
A general form of discharge coefficient for entrance flowmeters, c = c 0 - c 1 Re c 2 is suggested and used to fit the calibrating data successfully. The main problem concerns to solve a set of nonlinear sequations, which is solved by a series of solutions of linear equations. This fitting equations are valuable and suitable for some other flowmeters.
Based on the operating principles of elbow flow meters, this paper states that the core of standardization of elbow flow meters is the standardization of hardware's structural dimension. On condition that the elbow flow meters' feature structural dimension parameters R/D are strictly kept the same, the flow coefficients of elbow flow meters with the same conduit diameter determined by experiments have good consistency. Comparison of the experimental results of several elbow flow meters with different conduit diameters shows that the flow coefficient increases as the conduit diameter...
According to statistics, about 90 % natural gas flow meters used in America and Canada are orifices. In China, the figure is approximately 85 %. As we know there are 8 geometric parameters primarily affect the orifice measurement performance. And in the past, some parameters can be measured by several large instruments in labs, but the others such as upstream edge radius cannot be given the quantitative value. It is only estimated by experiences. Now all of the values are obtainable due to the development of the new portable 8 geometric parameters measurement instrument, which make use of...
Flow meter is calibrated by flow standard facilities by master meter method, is becoming trend of flow meter calibration method. The research of the calibration method and evaluation of uncertainty are focused in science field. This paper analyzes the influence facts of the process of calibration of flow meter by standard meter method around the calibration of turbine flow meter by standard turbine flow meter, establishes the mathematical model and give out the evaluation method and program of calibration uncertainty.The method was verified by test.
The components and testing results of working standard equipment for natural gas flow meter used multi-path ultrasonic meters in this paper. The testing results in different conditions by NMi of Netherlands, PTB of Germany and CVB of China showed that the uncertainties of the DN100 and DN300 meters for the standard equipment could meet the requirement of 0.5 % and 0.35 % respectively
This paper introduced a piston-type dynamic flow standard device and the method for applying step flow rate to the turbine flowmeter. Setting up math model of the turbine flowmeter and analyzing the dynamic parameter (step response time constant) and things that affect dynamic performance of the flowmeter in theory. Acquiring the step flow response data of the flowmeter by experiment and calculating the time constant. The reality result is consistent with theory.
In the uncertainty of measurement evaluation it is essential a solid grasp of the physical and mathematical theory underlying the measurement model to make a sensible analysis of the experimental data. There may occur particular situations, which lead to results in apparent contradiction to our usual understanding of error analysis. This paper presents a detailed case of such situations arising in a flow meter calibration model.