The LJ series V-cone (V-cone, inner cone, cone) flowmeter is a new type of differential pressure flow sensor. It adopts a unique center streamline throttling structure design, cleverly solving the problem of long straight pipe rectification. The streamlined cone suspended at the center can reshape the flow velocity curve. In the narrow areas immediately upstream and downstream of the cone (front 0-3D, back 0-1D), the fluid with irregular flow velocity can be directly rectified into an ideal fluid, achieving high measurement accuracy and repeatability without the need for straight pipe rectification. Under normal circumstances, the range ratio is 10:1, and selecting appropriate parameters can achieve 30:1. At the same β value,V-cone flowmeterThe permanent pressure loss is about 1/5-1/10 of the orifice plate, which can greatly reduce operating energy consumption. Another major feature of the V-cone flowmeter is its self purging structural design, which eliminates dead zones. When the medium flows through the cone, it accelerates and continuously flushes the positive pressure tapping hole, the outer wall of the cone, and the pipe wall near the cone, while the negative pressure tapping hole is isolated by a small section of non flowing medium, preventing dirt and impurities from entering. Therefore, the V-cone flowmeter can be used for various dirty media containing impurities and easy crystallization, such as coke oven gas, blast furnace gas, etc., which are not easily blocked after long-term use. Can be used for special dirty media with high viscosity, impurities, and easy scaling, such as residual oil, crude oil, recycled oil, coal water slurry, benzene, liquid sulfur, etc. Widely used in industries such as petroleum, chemical, light industry, steel, textile, food, environmental protection, energy, etc.

When the medium flows in the direction of the cone tip at a certain speed, due to the throttling effect of the cone, a low-pressure zone is immediately formed downstream of the cone. The high-pressure PH is taken from the upstream pipe wall of the cone, and the low-pressure PL is taken from the hollow pipe connected to the tail of the cone, which is sent to the differential pressure transmitter to measure the differential pressure value △ P. According to the Bernoulli equation, the fluid velocity can be calculated, and then multiplied by the pipe cross-sectional area S and instrument coefficient K to calculate the volumetric flow rate qV.

No requirement for straight pipe sections
LJVVG seriesV-Cone flowmeterAdopting a unique center streamline throttling structure design, the streamline cone suspended at the center can reshape the flow velocity curve, and in the narrow areas immediately upstream and downstream of the cone (front 0-3D, back 0-1D), the flow velocity is irregular

The fluid is directly rectified into an ideal fluid, achieving high measurement accuracy and repeatability without the need for straight pipe rectification.

High precision and good repeatability
LJVVG seriesV-Cone flowmeterpositive pressureThe hole is located on the pipe wall upstream of the cone, and the pressure measurement position is chosen at the ideal fluid

In the constant velocity region, in accordance with Bernoulli's theorem, the positive pressure signal is stable, and the negative pressure hole is located at the center of the tail of the cone, exactly in the area with the lowest downstream pressure. Due to the symmetrical structure of the cone center, the negative pressure signal fluctuates very little, and the output differential pressure signal is very stable. The sensor accuracy is better than 0.5% of the reading, with a repeatability of ± 0.1%. The accuracy of the trade measurement type is as high as ± 0.3%. (Choose the appropriate range of measurement)

Wide range ratio and low pressure loss
The normal range ratio of LJVVG series V-cone flowmeter is 10:1, and selecting appropriate parameters can achieve 30:1. At the same β value, the permanent pressure loss of the inner conical flow sensor is about 1/5 to 1/10 of that of the orifice plate, which can greatly reduce operating energy consumption.
Large differential pressure value on the scale
LJVVG seriesV-Cone flowmeterThe scale differential pressure is large and can be flexibly selected. Wind measurement in power plants, gas measurement in steel mills, etc

Good long-term stability
The unique streamline cone throttling of the V-cone flowmeter has a "streamline body boundary layer effect", which prevents dirty fluids from wearing down the throttling edge. Its β value can be guaranteed to remain unchanged for a long time, and the entire instrument has no movable parts, so there is no need for repeated calibration, and it has long-term stability

Stability.
Can handle high-temperature and high-pressure media on the side
Like orifice plates and other throttling devices, the working temperature and pressure of V-cone flow meters depend on the materials and grades of pipelines and flanges. The working temperature can reach 850 ℃ and the pressure is 42.0MPa.
Capable of handling complex working conditions with media
Due to the unique structure of the throttling fluid,V-Cone flowmeterCan measure gas-liquid two-phase media (such as moisture), multiphase water flow, vibrating water flow, electromagnetic interference media, various mixed gases, etc.

1. Low voltage type (PN2.5 or below) LJVVG-1, LJVVG-3, LJVVG-4, LJVVG-5

2. High voltage type (PN4.0~PN10) LJVVG-1, LJVVG-3, LJVVG-4, LJVVG-5

3. Advantages
Advantages of using a regular differential pressure transmitter:
Cost advantage:
Equipped with a regular differential pressure transmitter, it can output a 4-20mA signal that is proportional to the square of the flow rate, and then send it to a computer or flow integrator to calculate the flow rate.
Fewer switch valves and fittings, saving installation costs.
No need for heat tracing to prevent freezing in winter.

Advantages of using a multivariable transmitter:
Equipped with a multivariable transmitter, the body can display the instantaneous accumulated flow rate and perform temperature and pressure compensation and flow accumulation calculation. And it can output 4-20mA.
Precision advantage:
Precision advantage:
Real time full parameter dynamic digital compensation technology: realizing temperature compensation function, which is the basic function of V-cone flowmeter. This can also be achieved by ordinary flow integrators, but the difference is that the VCF internal cone flowmeter uses real-time full parameter dynamic digital compensation, rather than the mapping reference correction of ordinary integrators.
Functional advantages:
Due to the use of multi parameter and Hart communication, users can measure multiple parameters through a single instrument. The LJVCF internal cone flowmeter installed on site can be remotely operated from a PC in the control room or adjusted with a handheld device in a portable state. At the same time, the on-site button mode of the V-cone flowmeter allows users to directly set buttons on site.
V-cone flowmeterIntegrated with the key functions of the flow integrator, it simplifies the compensation calculation work of DCS or secondary meters. When using 4-20mA as the transmission signal, DCS or secondary meters only need to have cumulative/alarm/recording/power supply functions. In systems using Hart as the transmission signal, the second/third/fourth measurement of the transmitter can also be continuously tracked and monitored.
Cost advantage:
A V-cone flowmeter can output multiple variable transmitters for flow/pressure/temperature, which can save procurement costs.
Fewer transmitters, fewer wiring, fewer valve switches, saving installation costs.
The transmitter directly outputs instantaneous or cumulative flow, simplifying the system resources for flow accumulation calculation, making it more convenient to connect to DCS and saving system costs.
Programs can be customized according to specific needs to increase software added value, without the need to purchase secondary tables, saving hardware costs.

4. Schematic diagram of multivariable integrated V-cone flowmeter

5. Technical specifications of multivariable transmitter
Power supply range: DC15V~45V
output
Output signal: two-wire system, 4-20mA output (Hart) (users can choose to output absolute pressure, temperature, instantaneous and cumulative flow)
Output signal limit: 1min is 3.5mA, configurable standard setting 1min is 3.8mA, and 1max is 20.5mA.
Alarm current: configurable 1min is 3.5~4mA, standard setting is 3.6mA, configurable 1max is 20~22.5mA, standard setting is 21mA
Communication distance: The maximum communication distance using multi-core twisted pair cable is 1.5Km. The communication distance varies depending on the cable type, and the cable length can be determined using the following formula:

Applicable cable outer diameter: φ 8.5 ± 0.5mm
Shell protection
Shell: cast aluminum, epoxy resin spray coating, nitrile rubber O-ring
Protection level: IP67
Temperature 0~100% RH