1. External clamp-type ultrasonic flowmeter;

The selection of ultrasonic flowmeter depends on the process conditions, the system adjustment range and the nature of the fluid, should consider the size of the metering pipeline flow, changes and fluctuations, corrosion, cleanliness, operation and economic and reasonable factors. A good flow meter should be able to cover a wide flow range and have good linearity.

Ultrasonic flowmeters with different installation methods have different application ranges. Under normal circumstances, the pipe segment ultrasonic flowmeter is suitable for high accuracy requirements and small caliber; On the contrary, the external clamp-type and other types of ultrasonic flowmeters are suitable for cases where the measurement accuracy is not high and the caliber is large.

To correctly select the ultrasonic flowmeter, in addition to the above factors to be considered, there are some unique factors to be considered.

Second, the external clamp type ultrasonic flowmeter installation picture;

In the design of natural gas station and yard, the design flow rate of natural gas is usually the volume flow rate under standard condition, which needs to be converted into the flow rate under working condition according to the gas composition. Therefore, the gas composition has a certain influence on determining the flow rate range.

Ultrasonic flowmeters have a wide range, and under the condition of ensuring high metering accuracy, the flow rate can usually be from 1 m/s to 30 m/s, or greater. Therefore, the choice of caliber can generally be smaller than the size of the main pipe, which can reduce the overall investment in the straight pipe section and the front and back valves in the metering station. But at the same time, it is also necessary to take into account the requirements of the process for the allowable pressure drop of the pipeline, and carry out comprehensive consideration of the selection.

In the national "Natural gas Engineering Design Code", based on the safety perspective, the upper limit of gas flow speed in natural gas pipelines has made a clear regulation. In the actual selection, the choice of flow rate in most cases should be lower than the specified upper limit, in order to avoid the throttling parts and elbows and other components in the high-speed gas through the vibration, resulting in high-frequency noise, the impact on ultrasonic metering.

In addition, at present, only a few national calibration stations have the real flow calibration capability of gas ultrasonic flowmeters, and the largest calibration caliber is DN400. Therefore, in the selection, we should pay attention to the problem of matching with the calibration ability.

Third, the use of external clamp-type ultrasonic flowmeter instructions;

Liquid ultrasonic flowmeters have been recognized by the market in recent years, and have a certain application, but most of them are used for water measurement and leak detection. Since the issuance of JJG 1030-2007 ultrasonic flowmeter verification regulations, the use of trade measurement on other crude oil and petroleum products has begun to be promoted. Although the ultrasonic flowmeter has a strong flow capacity, no moving parts, and a wide range of applicable media, because its technology is relatively new, the composition of the measurement program needs to be carefully considered.

In the selection, it is necessary to first consider the water content, gas content, impurities and other conditions in the oil, if the above composition exceeds the allowable range of suppliers, the accuracy is difficult to guarantee. In addition, whether the fluid medium flows in full tube is very important for accurate measurement.

Thirdly, the selection needs to be based on the viscosity and Reynolds coefficient of the fluid to ensure that the flowmeter can achieve the required accuracy over the entire operating range.

Similarly, the calibration of liquid ultrasonic flowmeter also has the problem of matching the capacity of existing calibration facilities and flowmeter caliber. Therefore, in the measurement of petroleum and its products, for large caliber liquid ultrasonic flowmeters, the on-site calibration method should be considered in the selection. At present, a master table is used as the standard table for numerical transmission. In the field of water measurement, calibration methods including dry scale are considered.

Fourth, the principle of external clamp type ultrasonic flow meter

When ultrasonic waves propagate in the fluid, their velocity is affected by the velocity of the fluid. By measuring the velocity of ultrasonic waves in the fluid, the velocity of the fluid can be detected and the flow rate can be converted. Taking the most widely used time difference ultrasonic flowmeter as an example, when the ultrasonic wave propagates in the fluid, the propagation speed of the ultrasonic wave in the downstream direction will increase, and the counter-current direction will decrease, that is, the same propagation distance will have different propagation time, and then the relationship between the propagation speed and the velocity of the measured flow body will be obtained to convert the flow rate. That is, when the ultrasonic beam propagates between the "upstream sensor" and the "downstream sensor" on the flow direction of the water medium in the pipeline, the flow of water will make the propagation time of the ultrasonic beam produce a small change relative to the static propagation, and the change in the propagation time is proportional to the flow rate of water, which is the measurement principle of the time-difference ultrasonic flowmeter. The theoretical expression of the relation is as follows: V=MD/sin2θ×△T/TupTdown

Where, M - is the number of linear propagation of the ultrasonic beam in water

θ - is the Angle between the ultrasonic beam and the direction of water flow

Tup - the propagation time of the ultrasonic beam in the positive direction (the propagation time from the upstream sensor to the downstream sensor)

Down - the propagation time of an ultrasonic beam in the reverse direction (the propagation time between the downstream sensor and the upstream sensor)

△T= Tup—Tdown

Five, external clip type ultrasonic flowmeter installation video;

Recently, the company received a call from a pipeline installation customer who has maintained a good cooperation relationship for a long time, asking about the ultrasonic flow meter for measuring sewage flow. After communication, we learned that the customer has installed flowmeters for many sewage pumping stations in Xiamen, some of them are pipeline-type electromagnetic flowmeters on site, and some are plug-in flowmeters. This site is located in Xiamen Xiang 'an District of the Utian pump station, the site the earliest installation of the pipe flowmeter, and later installed the plug-in flowmeter, are broken, can not be measured normally, but the current can not stop the water, re-install the pipe flowmeter, therefore, the customer found us Sunac, order one installed in the pipe wall can measure the flow of ultrasonic flowmeter, To be allowed to change to the pipeline type sewage flowmeter.

Because we SunAC and this pipeline installation customer has always maintained a good cooperative relationship, so this cooperation is also a natural result. The following are the photos taken by our SunAC staff on the scene for your appreciation:

Shanghai Kekun is a professional instrument sales enterprise, the general agent of Fuji Electric (China) Co., LTD. A full range of products Fuji ultrasonic flowmeter, ultrasonic flowmeter, Fuji flowmeter, Fuji frequency converter, Fuji analyzer The main products are imported ultrasonic flowmeter, portable ultrasonic flowmeter, external clamptype ultrasonic flowmeter, Handheld ultrasonic flowmeter Fixed ultrasonic flowmeter Ultrasonic flowmeter, electromagnetic flowmeter, vortex flowmeter, orifice flowmeter, flowmeter calibration

Wang Wenxue

Best   Regards!

Shanghai Kekun Industrial Technology Development Co., LTD. Fuji ultrasonic flowmeter China general agent

shanghai Kekun Industrail Thecnology Dvelopment Co.,Ltd

Address: Room 206, Building 1, No. 129 Xuanqiu Road, Pudong New Area, Shanghai

Mobile: 15901759876

Email: wangwx2081@163.com