• Name: One-piece type cone flowmeter
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Cone flow meter

 

Product Introduction:


Cone flowmeter is new type of differential pressure flowmeter.

Since American company, Micrometer released, the cone flowmeter is widely used. It could measure every kind of Reynold number , and could meet the application condition of all kinds of medium..

The principle of operation is same as other kinds of differential pressure flowmeter that all are based on the conservation of energy of the sealing pipe. Yet due to the unique design structure which enlarge the measurement range of flow, and avoid the limitation of classic differential pressure flowmeter.

So the performance is better. After a long use to prove, comparing with the general differential pressure flowmeter ,the cone flowmeter has the advantages of high accuracy for the long term, good repeatability, less limitation of installation conditions, wear resistance ,wide measurement range.

The cone flowmeter hangs a cone throttling element, and the element obstacles the flow of the medium, and remold the doppler waveform, which could immediately form the low pressure zone at the downstream of the cone element.

There is a differential pressure between the positive pressure of the upstream of the pipe and the negative pressure of the downstream after the throttling element throttles, and the positive pressure and the negative pressure was taken out. The positive pressure port is situated the upstream of the pipe, and the negative pressure is situated the end of the cone.

Through measuring the differential pressure between them, and based on the Bernoulli equation, the flowmeter in the pipe could be calculated. The cone is situated at the central of the pipeline, which could optimize the Doppler waveform of the medium, so the measurement accuracy is high, and which has the low requirement for the straight pipe section of the upstream and downstream of the instrument.

The cone flowmeter could measure the medium including water, stream, air, gas, nitrogen, coke oven gas etc. The condition of the flow could be from the very low temperature to the supercritical state.

The highest working temperature is 700℃,and the largest pressure is 40.5Mpa.

 

Working mechanism:


The cone flowmeter is differential type one, and the mechanism is same as other general differential pressure flowmeter. They are all based on the Bernoulli’s law.

Under the condition of stable flowfield, the flow speed in the pipe and the square root of the differential pressure is directly proportional. The upstream pressure is P1, the downstream pressure is P2, and the producing the differential pressure is △P,So,

 

△P=P1-P2,

the equation of the β value of the throttle

Thereinto: D the inner diameter of the pipe; d: the outer diameter of the cone throttle element.

△P(differential pressure)ρ(flow density) 

 

Basic Parameter:

Measured medium: liquid, air, stream
Nominal diameter: DN15-DN500, the larger diameter could be specially customized.
The temperature range: -60~ 600℃,it could be higher if the special material is applied.

Nominal pressure:≤10MPa, the higher pressure specification could be specially customized.

The instrument material: 1Cr18Ni9Ti, 20#isteel, alloy steel.

The uncertainty: the sensor ±0.5%, the system precision: ±1.0%

The power supply: 24VDC

The surrounding temperature: -30~ 65

Explosion-proof grade: ( ia )CT2 - T5 intrinsically explosion proof
The surrounding humidity: relative humidity: 45 ~ 85%

Output signal: 4 ~ 20mA((load resistance ≤500Ω; HART digital signal
β value range: 0.45 ~ 0.85

Range span: normal range1:15, the range after expansioin:1:30

Repeatability: ±0.1%
Straight pipe section requirement: upstream1-3D, downstream0.5-1D

 

Structure features:


The flow formula of the cone flowmeter is same as the other differential pressure flowmeter. Yet the geometry is absolutely different. It is throttled by a cone hanged in the centre of the pipe which forces the fluid centered the center of the pipeline flows surrounding the cone.

The geometry of the circular cone has much more advantages compared with the traditional throttle element. It takes for many years for the cone shape design and test, providing the best performance under different environment.

For understanding the features of the cone flowmeter, it must understand the distribution feature of the velocity in the pipe. As figure shows, if the fluid in the pipe does not be interfered and interfered by any other factor, it could form the ideal flow field.

Through the pipe centreline to silver the pipe to look the ideal flow field, the velocity distribute: the velocity closing zero against the pipe skin, the more closing to the centre of the pipe , the larger the velocity is.

The velocity in the centre of the pipe is the most( due to the friction force decrease the speed of the fluid flowing through the pipe skin.)

 

Because the cone hang the centre of the pipe, which directly has mutual effect with the high speed centre part of the fluid, to force the high speed core and low speed fluid near the pipe skin equably to change.

Yet other differential flowmeters opening pore at the centre do not have this function. This is one of the many advantages of the inner cone flowmeter, so even if the velocity is decreased, the cone flowmeter could also produce the accurate differential pressure by the continuously mutual effect between the fluid and the highest velocity of the pipe centre. Yet the traditional differential pressure flowmeter could not measure so long ago.