Introduction to Turbine Flow Meter

A turbine flowmeter generally consists of two parts: a sensor and a display instrument, or it can be made as a whole.

Volumetric flow meters and Coriolis mass flow meters are known as the three types of products in flow meters, and their products have developed into multiple varieties and series batch sizes. A flow meter that uses a turbine for measurement. It first converts the flow rate into the rotational speed of the turbine, and then converts the rotational speed into an electrical signal proportional to the flow rate. This type of flowmeter is used to detect instantaneous flow and total cumulative flow, and its output signal is frequency, which is easy to digitize.

When the ferromagnetic turbine blades pass through the magnet, the magnetic resistance of the magnetic circuit changes, thereby generating an induction signal. The signal is amplified and shaped by an amplifier and sent to a counter or frequency meter to display the total accumulated flow rate. Simultaneously, the pulse frequency is converted from frequency to voltage to indicate instantaneous flow rate. The rotational speed of the impeller is proportional to the flow rate, and the rotational speed of the impeller is proportional to the total amount of flow. The output of the turbine flowmeter is a frequency modulated signal, which not only improves the anti-interference ability of the detection circuit, but also simplifies the flow detection system. Its range ratio can reach 10:1, and the accuracy is within ± 0.2%. The inertia is small and the size is small. The time constant can reach 0.01 seconds.

1、 Advantages of turbine flowmeter:

(1) High precision, among all flow meters, belongs to the precise flow rate category

(2) Good repeatability;

(3) Yuan zero drift, good anti-interference ability;

Turbine flow meters are widely used in measuring objects such as petroleum, organic liquids, inorganic liquids, liquefied gas, natural gas, and low-temperature fluids. Turbine flow meters are second only to orifice flow meters in terms of usage, and gas turbine flow meters with pressures ranging from 0.8 to 6.5 MPa have become excellent natural gas measuring instruments

purpose
Turbine flowmeter is a speed type instrument with high accuracy, good repeatability, simple structure, few moving parts, high pressure resistance, wide measurement range, small volume, light weight, low pressure loss, and easy maintenance. It is used to measure the volumetric flow rate and total amount of low viscosity gases in closed pipelines. It has a wide range of practical value in industries such as petroleum, chemical, metallurgical, and urban gas pipeline networks.

Precautions for installation of turbine flowmeter

In order to ensure the accuracy of the measurement of the turbine flowmeter, the installation position and method must be selected correctly. The requirements for the straight pipe section are as follows: the flowmeter must be installed horizontally on the pipeline (with a pipeline inclination within 5 degrees), and the axis of the flowmeter should be concentric with the axis of the pipeline during installation, with a flow direction of *.

The upstream pipeline length of the flowmeter should have an equal diameter straight pipe section of not less than 2D. If the installation site permits, it is recommended that the upstream straight pipe section be 20D and the downstream be 5D.

Requirements for piping: The inner diameter of the upstream and downstream piping at the flowmeter installation point should be the same as the inner diameter of the flowmeter. Requirements for bypass pipe: In order to ensure that the maintenance of the flowmeter does not affect the normal use of the medium, shut-off valves (globe valves) should be installed on the front and rear pipelines of the flowmeter, and a bypass pipe should also be installed. The flow control valve should be installed downstream of the flowmeter. When using the flowmeter, the upstream shut-off valve must be fully opened to avoid unstable flow of fluid in the upstream section.

Requirements for external environment: When the flowmeter is installed indoors and must be installed outdoors, it must be protected from sunlight and rain Lightning protection measures should be taken to avoid affecting the service life.

Requirement for impurities in the medium: In order to ensure the service life of the flowmeter, a filter should be installed before the straight pipe section of the flowmeter.

Installation location: The flowmeter should be installed in a location that is easy to maintain, free from strong electromagnetic interference and thermal radiation.

Requirements for installation welding: The user shall provide another pair of standard flanges to be welded onto the front and rear pipelines. Welding with flow meters is not allowed! Before installing the flowmeter, welding slag and other dirt in the pipeline should be strictly removed, and an equal diameter pipeline (or bypass pipe) should be used instead of the flowmeter to blow the pipeline. To ensure that the flow meter is not damaged during use. When installing a flowmeter, the sealing gasket between the flanges should not be recessed into the pipeline.

Requirements for flowmeter grounding: The flowmeter should be reliably grounded and cannot be shared with the grounding wire of the high-voltage system.

Requirements for explosion-proof products: In order to ensure the safe and normal use of the instrument, the usage environment of the explosion-proof flowmeter should be reviewed to ensure compliance with the user's explosion-proof requirements. During installation and use, strict adherence to the national requirements for the use of explosion-proof products is required. Users are not allowed to change the connection method of the explosion-proof system or open the instrument at will.

Select within the specified flow range to prevent overspeed operation, ensuring ideal accuracy and normal service life.

Before installing the flowmeter, the pipeline should be cleaned of debris such as fragments, welding slag, stones, dust, etc. It is recommended to install a 5-micron sieve filter upstream to block liquid droplets and sand particles.

When the flowmeter is put into operation, the front valve should be slowly opened first, and then the rear valve should be opened to prevent instantaneous airflow impact and damage to the turbine. Lubricating oil should be added according to the signs, and the frequency of refueling depends on the cleanliness of the gas, usually 2-3 times a year. Due to pressure testing, pipeline purging, or exhaust causing turbine overspeed operation, as well as turbine operation in reverse flow, the flow meter may be damaged.

It is not allowed to open the flowmeter randomly before operation Rear cover, modify internal parameters, otherwise it will affect the normal operation of the flowmeter.

Be careful when installing the gasket to ensure that no protrusions enter the pipeline to prevent interference with normal flow measurement. When calibrating a flowmeter, pressure should be collected at the pressure tap of the flowmeter.