Flow meter purchase method

The general selection can be considered from five aspects, which are flow meter performance, fluid characteristics, installation conditions, environmental conditions and economic factors. The detailed factors in the five aspects are as follows:

Instrument performance: accuracy, repeatability, linearity, range, flow range, signal output characteristics, response time, pressure loss, etc.;

Fluid properties: temperature, pressure, density, viscosity, chemical corrosion, abrasiveness, fouling, miscibility, phase change, electrical conductivity, acoustic velocity, thermal conductivity, specific heat capacity, isentropic exponent;

Installation conditions: pipeline layout direction, flow direction, length of straight pipe on the upstream and downstream sides of the test piece, pipe diameter, maintenance space, power supply, grounding, auxiliary equipment (filter, air eliminator), installation, etc.;

Environmental conditions: ambient temperature, humidity, electromagnetic interference, safety, explosion-proof, pipeline vibration, etc.;

Economic factors: instrument purchase fees, installation fees, operating fees, calibration fees, maintenance fees, instrument life, spare parts, etc.

Flow meter instrument selection steps are as follows:

1, according to the type of fluid and five considerations for the initial selection of instrument types available (to have several types for selection);

2. Collect data and price information for the type of primaries, and prepare conditions for in-depth analysis and comparison;

3, using the elimination method to gradually focus on 1 to 2 types, the five factors must be repeatedly compared and analyzed to determine the pre-selected goals.

Precautions Fluid characteristics mainly refer to gas pressure, temperature, density, viscosity, compressibility, etc. Since gas volume changes with temperature and pressure, consideration should be given to whether or not to compensate for the correction.

Instrument performance refers to the accuracy, repeatability, linearity, range ratio, pressure loss, initial flow, output signal, and response time of the instrument. When selecting the flowmeter, it should be carefully analyzed and compared against the above indicators, and the selection can meet the requirements for measuring the flow of medium. meter.

Installation conditions refer to gas flow, pipeline orientation, length of upstream and downstream straight pipelines, pipe diameter, space location and pipe fittings, which will affect the accurate operation, maintenance and service life of gas gas flow meters.

Economic factors refer to purchase fees, installation fees, maintenance fees, calibration fees, spare parts, etc., which in turn are affected by the performance, reliability, and longevity of gas-fired gas meters.

Accuracy grades and functions Select the instrument accuracy grade according to the measurement requirements and the use occasions, so that it is cost-effective. For applications such as trade settlement, product handover, and energy metering, select a precision level, such as 1.0, 0.5, or higher, for process control applications. Select different levels of accuracy based on the control requirements. Some of these are just occasions to check the process flow, and do not require precise control and measurement. You can choose a lower accuracy class, such as 1.5, 2.5, or even 4.0, then you can use inexpensive plug-in electromagnetic flowmeter to measure the medium When the flow rate, instrument range, and bore diameter are used to measure general media, the full flow of the electromagnetic flowmeter can be selected within a wide range of 0.5 to 12 m/s. The selected instrument specification (diameter) is not necessarily the same as the process piping. It should be determined whether the measurement flow range is within the flow rate range. That is, when the flow rate of the pipeline is too low to meet the requirements of the flow meter or the accuracy of the measurement is not guaranteed at this flow rate, it is required. Reduce the diameter of the instrument to increase the flow rate in the tube and obtain satisfactory measurement results.