DeltaPbar Flow Meter

Brief introduction:

The HQ-VLB flow meter is suitable for high-precision flow measurement of gases, liquids, and steam. The VLB is a differential pressure, velocity-averaging flow sensor that measures flow rate by detecting the differential pressure generated by the sensor in the fluid. The VLB reflects the true fluid velocity, achieving an accuracy of ±1.0% and a repeatability of ±0.1%.

Detailed description:

Verabar Flow Meter

The V-Bar flow meter is suitable for high-precision flow measurement of gases, liquids, and steam. The V-Bar is a differential pressure, velocity-averaging flow sensor that measures flow rate by the differential pressure generated by the sensor in the fluid. The V-Bar reflects the true fluid velocity, with an accuracy of ±1.0% and repeatability of ±0.1%.

I. Advantages of the V-Bar Flow Meter: The outstanding advantage of the V-Bar is that it outputs a very stable, non-pulsating differential pressure signal.

II. Features of the V-Bar Flow Meter Probe:

The bullet-shaped probe generates an optimal pressure distribution and a fixed fluid separation point; the low-pressure taps located on both sides of the probe, before the fluid separation point, generate a stable differential pressure signal and effectively prevent clogging. The integrated internal structure prevents signal leakage, improves the structural strength of the probe, and maintains long-term high accuracy.

With its excellent anti-clogging design, the V-Bar flow probe completely overcomes the drawbacks of easy clogging in insertion-type flow probes such as the Annubar, bringing the anti-clogging level of averaging pitot tube flow probes to an unprecedented level.

The high-pressure tap of the probe will not be blocked. A high-pressure zone is formed at the front of the probe, with a pressure slightly higher than the pipe static pressure, preventing particles from entering. Please note: the fluid velocity at the high-pressure tap of the probe is zero, so no objects will enter the tap. When the system is started, the fluid enters the bent tube under the action of the pipe static pressure, quickly forming a pressure equilibrium state. Once the pressure equilibrium state is formed, the fluid encounters high pressure at the inlet of the bent tube, bypasses it, and no longer enters the bent tube.

The low-pressure tap of the V-Bar achieves inherent anti-clogging. Under normal circumstances, dust, sand, and particles are concentrated at the rear of the probe due to vortex shedding forces. This is why autumn leaves always accumulate behind houses on the leeward side. Other probes, due to their low-pressure taps being located in the vacuum zone at the tail of the probe, are quickly clogged by impurities brought by vortices under the action of vortex shedding forces. The unique design of the V-Bar places the low-pressure taps on both sides of the probe, before the fluid separation point and the wake region. This design inherently prevents clogging and generates a very stable low-pressure signal.

III. Advantages of the V-Flow Flow Meter Probe:

1. Can measure various media, with a wide range of applications;

2. High accuracy and large turndown ratio;

3. The probe's pressure tapping holes are inherently clog-resistant;

4. Stable measurement signal with minimal fluctuations;

5. Low pressure loss in the pipeline;

6. Unique high-strength bullet-shaped single-piece dual-chamber structure;

7. Low installation costs and virtually maintenance-free;

8. Can be installed and serviced online.

IV. Sensors of the Verabar Flow Meter

1. Stable Signal

The Verabar's low-pressure tap is located on both sides of the probe, between the fluid and the probe separation point, away from the vortex fluctuation area.

2. High Accuracy

The Verabar guarantees long-term accuracy stability because:

(1) It is unaffected by wear, dirt, and oil.

(2) It has no moving parts in its structure.

(3) The design eliminates clogging. In the front of the probe, a high static pressure zone surrounds the probe, preventing the high-pressure tap from being blocked. Importantly, the low-pressure taps are located on both sides of the probe, where the fluid flows obliquely across the surface, protecting the low-pressure taps from being blocked. Other probes are prone to clogging because their low-pressure taps are located in low-pressure fluctuation areas where impurities accumulate.

3. Low Installation Cost

(1) Only a few inches of line welding are required, making installation very simple and quick.

(2) On-line installation under pressure can be achieved using special tools.

(3) All valves and instrument interfaces require only simple assembly, resulting in very low assembly costs.

4. Low Operating Cost

(1) As a non-constricting throttling design and an insertable flow probe, the Verabar has low operating costs.

(2) The Verabar generates very low pressure loss, typically less than 0.7 KPa.

(3) An orifice plate element generates a pressure loss exceeding 14 KPa.

(4) Compared to an orifice plate, the Verabar reduces energy loss by 95%.

The continuous operation of the Verabar fundamentally eliminates the possibility of clogging. However, attention should still be paid to preventing clogging in the following situations:

(1) When the pressure tap line leaks, the high-pressure balance zone of the probe is disrupted, and smaller particles in the impurities may enter the pressure tap.

(2) When the pipeline is shut down, due to Brownian motion of molecules, small particles of impurities may enter the pressure tap.

(3) Frequent system start-ups and shutdowns may cause small particles of impurities to enter the pressure tap during the instantaneous formation of the high-pressure zone. Over time,

this may lead to clogging of the probe. 4. The presence of large amounts of tar, algae, or fibrous substances in the medium can also cause probe blockage.

5. V-Cone Flowmeter Application of New Technology

The V-Cone with valve connector:  Adopts a brand-new design concept, providing a new approach by integrating an instrument shut-off valve at the instrument connector.

1. Simplifies installation and maintenance.

2. Reduces the number of assembly components, lowering hardware connection costs.

3. Quick installation system

4. Quick insertion and removal

5. Sealed drive system prevents component damage

6. Can be used for the installation of multiple probes

7. Complete installation in less than 1 hour

V. V-Cone Flowmeter Technical Specifications

V-Cone Flow Measurement System Performance Indicators

Measurement accuracy: ±1% Repeatability: ±0.1%

Applicable pressure: 0～40MPa Applicable temperature: -180℃～+550℃

Upper measurement limit: Depends on probe strength Lower measurement limit: Depends on the minimum differential pressure requirement

Turndown ratio: Greater than 10:1

Applicable pipe diameter: 38mm～9,000mm (round pipes, square pipes)

Applicable media: Full pipe, unidirectional flow, single-phase gases, steam, and liquids with viscosity not exceeding 10 centipoise. The V-Cone has an extremely wide range of applications and is widely used for measuring various gases, liquids, and steam.

The following are typical application media:

Gas, liquid, steam, natural gas, cooling water, saturated steam, compressed air, boiler water, superheated steam, fuel gas, demineralized water, gaseous hydrocarbons, liquid hydrocarbons, hot air, cryogenic liquids, producer gas, heat transfer fluids

VI. Working Principle of the V-Cone Flow Meter

When fluid flows through the probe, a high-pressure distribution zone is created at its front, where the pressure is slightly higher than the static pressure in the pipe. According to Bernoulli's principle, the fluid accelerates as it flows past the probe, creating a low-pressure distribution zone at the rear of the probe, where the pressure is slightly lower than the static pressure in the pipe. After the fluid flows past the probe, a partial vacuum is created at the rear of the probe, and vortices appear on both sides of the probe. The cross-sectional shape, surface roughness, and the position of the low-pressure tapping holes of the averaging flow probe are key factors determining the probe's performance. The stability and accuracy of the low-pressure signal are crucial for the accuracy and performance of the averaging probe. The V-Cone averaging flow probe accurately detects the average differential pressure generated by the average velocity of the fluid. The V-Cone averaging flow probe has multiple pairs of pressure tapping holes arranged according to specific criteria in the high and low-pressure zones, making accurate measurement of the average flow velocity possible.

V-Cone Flow Meter Measurement Principle

The V-Cone flow meter is an insertion-type flow measurement instrument. A V-Cone sensor is inserted into the pipeline. When the fluid flows through the sensor, a high-pressure distribution zone is created at the front (upstream) of the sensor, and a low-pressure distribution zone is created at the rear (downstream). The sensor has multiple pairs (typically three pairs) of pressure taps arranged according to a specific pattern in the high and low-pressure zones. These taps measure the total pressure (including static pressure and average velocity pressure) P1 and the static pressure P2 of the fluid, respectively. P1 and P2 are then fed into a differential pressure transmitter, which measures the differential pressure △P = P1 - P2. △P reflects the magnitude of the fluid's average velocity, from which the fluid flow rate can be calculated.

VII. Features of the V-Bar Flowmeter

1. Preparations Before Commissioning

① Correct Sensor Installation:

After the sensor is installed on the pipeline, a thorough inspection must be performed before commissioning.  Ensure the welding is secure, the direction is correct, there are no leaks, and the insertion depth is appropriate.

② Instrument Calibration:

The sensor is equipped with a differential pressure transmitter and a smart flow totalizer (and possibly a pressure transmitter and temperature transmitter). All instruments must be inspected and calibrated before use. The measurement range of the instruments must meet the requirements of the sensor and the measured medium. For example, if the maximum flow rate of the measured air is Qmax = 5000 m³/h, and the calculated maximum differential pressure generated by the sensor is

△Pmax = 0.6 KPa, then the measurement range of the differential pressure transmitter should be calibrated to 0~0.6 KPa, corresponding to a 4~20 mA DC current signal output. For general-purpose flow totalizers, the totalizer should be programmed and configured in advance according to the real-time flow range, differential pressure range, medium density, temperature, pressure, and flow calculation requirements, ensuring that the totalizer can correctly calculate and display the flow rate.

③ Correct Instrument Wiring:

The sensor, differential pressure transmitter, and flow totalizer form a measurement system. The power lines of the supporting instruments, the signal output and input lines between the instruments, and the control and alarm connections are clearly marked on the wiring boards (also known as terminal boards) of each instrument.  These must be correctly identified and selected. The instrument wiring must be repeatedly checked before commissioning. To properly prepare for commissioning, in addition to carefully reading the "V-Bar Flowmeter User Manual," you should also read the "Differential Pressure Transmitter User Manual," "Smart Flow Totalizer User Manual," and other relevant documents, and follow the instructions in the manuals.

V-Bar flowmeters belong to the category of differential pressure averaging pitot tube flowmeters. They all measure the flow rate of the fluid by measuring the differential pressure before and after the fluid passes through the flow meter. Therefore, when selecting and ordering a flow meter, the following parameters should be known:

1. Pipe diameter

2. Fluid properties

3. Fluid pressure in the process pipeline

4. Fluid temperature in the process pipeline

5. Fluid flow rate

VIII. V-Bar Flow Meter System Solution

1. HLV series averaging pitot tube flow sensor. The averaging pitot tube flow sensor is designed and manufactured according to the measured medium, the inner diameter of the user's pipeline, working temperature, working pressure, and flow rate variations.

2. Differential pressure transmitter or other models of differential pressure transmitters.

3. Pressure transmitter or other models of pressure transmitters.

4. Temperature transmitter or other models of temperature transmitters.

5. Flow totalizer or other models of flow totalizers.

The intelligent averaging pitot tube [V-Bar] flow meter, composed of the above components, can provide temperature and pressure compensation, and can display instantaneous flow rate, cumulative flow rate, medium temperature inside the pipeline, medium pressure inside the pipeline, and differential pressure values. It is equipped with a communication interface and 4-20mA output.

IX. Application Fields of V-Bar Flowmeters

V-Bar flowmeters have extremely wide applications, and the application of flow measurement technology and instruments generally covers the following areas:

1. Production Processes

Flow meters are one of the major categories of instruments in process automation instrumentation and equipment. They are widely used in various sectors of the national economy, including metallurgy, power generation, coal mining, chemical industry, petroleum, transportation, construction, light industry, textiles, food, medicine, agriculture, environmental protection, and people's daily lives. They are important tools for developing industrial and agricultural production, saving energy, improving product quality, and enhancing economic efficiency and management levels, occupying an important position in the national economy. In process automation instrumentation and equipment, flow meters have two main functions: as detection instruments for process automation control systems and as totalizers for measuring the quantity of materials.

2. Energy Measurement

Energy is divided into primary energy (coal, crude oil, coalbed methane, petroleum gas, and natural gas), secondary energy (electricity, coke, manufactured gas, refined oil, liquefied petroleum gas, and steam), and energy carriers (compressed air, oxygen, nitrogen, hydrogen, and water), etc. Energy measurement is an important means of scientifically managing energy, achieving energy conservation and consumption reduction, and improving economic efficiency. Flow meters are an important component of energy metering instruments.  Water, manufactured gas, natural gas, steam, and oil products—these commonly used energy sources—all utilize a vast number of flow meters, which are indispensable tools for energy management and economic accounting.

3. Environmental Engineering

The emission of flue gas, waste liquid, and wastewater seriously pollutes the atmosphere and water resources, posing a serious threat to the human living environment. The country has listed sustainable development as a national policy, and environmental protection will be the biggest challenge of the 21st century. To control air and water pollution, management must be strengthened, and the basis of management is the quantitative control of pollutant levels.

my country is a country that relies primarily on coal for energy, with millions of chimneys continuously emitting flue gas into the atmosphere. Flue gas emission control is a crucial project for pollution control, and every chimney must be equipped with flue gas analyzers and flow meters to form a continuous emission monitoring system. Measuring flue gas flow is very difficult due to the large size and irregular shape of the chimneys, variable gas composition, wide flow rate range, dirt, dust, corrosion, high temperature, and lack of straight pipe sections.

4. Transportation

There are five modes of transportation: rail, road, air, water, and pipeline. Although pipeline transportation has existed for a long time, its application is not widespread. With the increasing prominence of environmental issues, the characteristics of pipeline transportation have attracted attention. Pipeline transportation must be equipped with flow meters, which are the eyes for control, distribution, and scheduling, and are also essential tools for safety monitoring and economic accounting.

5. Biotechnology

The 21st century will be the century of life sciences, and industries characterized by biotechnology will develop rapidly. Many substances in biotechnology require monitoring and measurement, such as blood and urine. The development of instruments is extremely difficult, and there is a wide variety of types.

6. Scientific Experiments

Scientific experiments require a large number of flow meters, and the types are extremely diverse. Statistics show that a large portion of the more than 100 types of flow meters are used for scientific research purposes; they are not mass-produced or sold commercially. Many research institutions and large enterprises have dedicated teams to develop specialized flow meters.

7. Oceanography and Meteorology

These fields involve open channels, and generally require measuring flow velocity to then calculate flow rate. The physical principles and fluid mechanics basis of flow velocity meters and flow meters are common, but the instrument principles, structures, and operating conditions differ significantly.

X. Installation Precautions for V-Cone Flowmeters

The V-Cone flowmeter is a differential pressure, velocity-averaging flow sensor that measures flow rate by the differential pressure generated by the sensor in the fluid. It is suitable for high-precision flow measurement of gases, liquids, and steam. It can be installed on any plane (horizontal, vertical, or inclined). During installation, the influence of the measured medium on the pressure sensing lines must be considered. The following points should be noted during the installation of the V-Cone flowmeter:

1. For gas flow measurement in vertical pipes, the flowmeter can be installed on the horizontal plane of the pipe, at any position along the pipe's 360-degree circumference. For horizontal pipes, the pressure sensing connections of the flowmeter must be located below the pipe's centerline.

2. For liquid flow measurement in vertical pipes, the flowmeter can be installed on the horizontal plane of the pipe, at any position along the pipe's 360-degree circumference. For horizontal pipes, the pressure sensing connections of the flowmeter must be located below the pipe's centerline.

3. For steam flow measurement in vertical pipes, the two positive and negative pressure sensing connections should be on the same horizontal plane. One advantage of the V-Cone flowmeter is that it requires a relatively short length of straight pipe compared to other differential pressure flowmeters.

11. Installation Diagram of the PowerFlow Flow Meter