Insertion type equal velocity delta flowmeter

1、 Overview

The equal velocity tube delta bar sensor is a device that measures flow rate through differential pressure and is developed based on the principle of pitot tube flow rate measurement. It can measure the flow rate of fluids such as liquids, gases, and vapors. Due to the absence of moving parts, almost no pressure loss, easy installation and maintenance, and extremely low operating costs, it is highly favored by users. The sensor is composed of a detection rod, a pressure tap, and a guide rod. It crosses the inside of the pipeline perpendicular to the pipeline axis. Multiple pressure measuring holes are installed on the upstream side of the measuring rod to measure the average total pressure, and static pressure measuring holes are installed on the downstream and side flow surfaces to measure the static pressure. They are respectively led out by the total pressure guide tube and the static pressure guide tube. Based on the differential pressure between the total pressure and the static pressure, the flow rate through the pipeline is calculated. The static pressure on the back flow surface of the sensor can also be replaced by the static pressure on the flow tube wall. The average velocity tube flow transmitter is a flowmeter composed of sensors, pressure accessories, differential pressure transmitters, pressure transmitters, flow integrators, and other supporting components. Equipping the averaging tube flow sensor with our company's differential pressure transmitter, pressure transmitter, temperature transmitter, and flow integrator can form various types of averaging tube flow meters. Various types of averaging tube flow meters can also be composed of differential pressure transmitters, pressure transmitters, temperature transmitters, and flow integrators produced by any manufacturer.

2、 Measurement principle

The Delta flowmeter adopts a curved surface design, and the cross-section itself is symmetrical. The curved surface is divided into three parts (as shown in the right figure), and the facing part is a smooth section, allowing the probe to smoothly contact the medium; The second part is the acceleration section, which accelerates the flow velocity of the medium by an average of three times, and increases the pressure in the face section by increasing the contact surface with the medium; The third part is the peak of the high and low pressure boundary, where the resistance suddenly disappears and a low pressure zone is formed behind the probe. The actual color velocity spectrum can fully reflect the changes in the medium flow velocity. So, the design of the equal velocity tube Delta flowmeter probe meets the requirements of small pressure loss and large differential pressure

The multi-point pressure measuring holes on the upstream side of the sensor measure the total pressure, while the multi-point pressure measuring holes on the downstream side measure the static pressure. The differential pressure transmitter calculates the differential pressure between the total pressure and static pressure output by the sensor through the pressure pipe, and outputs a DC 4-20mA signal to the PLC or DCS to calculate the mass flow rate or volume flow rate (sometimes requiring temperature and pressure compensation). Xi'an Sanlian Measurement and Control provides an integrated intelligent multi parameter Deltaba flowmeter

3、 Characteristics and Applications

The probe of the Delta flowmeter manufacturer can be used for: ① various gas measurements, including air, humid gases, various pre - and post purification flue gases, high-temperature flue gases, compressed air, primary air, secondary air, etc; ② Various steam measurements, including steam, saturated steam, and superheated steam; ③ Measurement of various liquids, including water, fuel, and benzene.

(2) High precision, good repeatability, and large range ratio (1:30). The opening of the Delta flow probe is non-uniform, and the opening points are based on complex calculations using computational software. Manufacturing parameters are determined based on pipe diameter, medium, and main process parameters. The improvement of probe measurement accuracy makes the adjustment of measured parameters more precise.

(3) Design anti blocking features for probe pressure hole. The maximum opening size of the probe is 8mm. As long as the dust or particles in the medium are not greater than 130mg/m3, maintenance and blowing are not required. Installing nitrogen purging pipelines can accurately measure high dust gases such as blast furnace gas, coke oven gas, converter gas, and sintering flue gas in large pipelines.

(4) The streamlined probe cavity design ensures stable measurement signals with minimal fluctuations. And the number and distribution of pressure holes before and after are symmetrical, not afraid of reverse installation, and can also achieve bidirectional measurement.

(5) The pipeline has minimal pressure loss and low requirements for straight pipe sections. The plug-in flow probe can ensure an accuracy of 1% in a very short straight pipe section (front 4D, back 3D), and adopts a non constricting throttling design, which is at least 90% lower than the pressure loss of the orifice plate.

(6) Low installation cost, basically maintenance free, and can be installed and repaired online.

4、 System composition

The Deltaba flow measurement system is a flowmeter composed of sensors, pressure attachments, differential pressure transmitters, pressure transmitters, temperature transmitters, flow converters, and other supporting components. Mass flow rate or volume flow rate and thermal energy can be calculated. The Delta flowmeter is designed and manufactured according to the national standards GB/T2624.1-2006 and JJG640-1994 for measuring fluid flow in pipelines.