Vortex flowmeter is a volume flowmeter which measures the volume flow of gas, steam or liquid, the volume flow or mass flow under standard condition according to Karman's Vortex Principle. It can also be used as a flow transmitter in automatic control system.
This instrument adopts advanced differential technique, combined with isolation, shielding and filtering measures, overcomes the problems of poor vibration resistance and disorder of small signal data of other similar products, and adopts unique sensor encapsulation technology and protective measures to ensure the reliability of products. There are two types of products: basic type and compound type. The basic type can only measure flow signal, while the compound type can simultaneously measure temperature, pressure and flow. Each type has an integral and separate structure to adapt to different installation situations.
II. Working Principle
Vortex flowmeter is composed of vortex generator designed in the flow field, detection probe and corresponding electronic circuit. When the fluid flows through the vortex generator, two alternating rows of vortices are formed on both sides of the vortex generator, which are called Carmen vortices. Based on Carmen Vortex Street Theory, Strouhal put forward that the frequency of Carmen Vortex Street is proportional to the velocity of fluid, and gave the relationship between frequency and velocity:f=St×V/d
These alternating vortices form a series of alternating negative pressure, which acts on the detection probe and generates a series of alternating signals. After the pre-amplifier conversion, shaping and amplification, the pulse frequency signal (or standard signal) which is proportional to the synchronization of the vortices is output.
III. Characteristics and Use of the Instrument
◆It has no movable parts, has long-term stability, with the simple structure, which makes it easy to be installed and maintained
◆The output of the sensor is pulse frequency, and its frequency is linearly related to the actual flow rate of the measured fluid. It has zero drift and very stable performance. The flow sensor has various structures, such as pipeline type and insertion type.
◆It supports high accuracy. Usually it supports a measurement accuracy of ±1.0% for liquids and a measurement accuracy of ±1.5% for gases.
◆It supports a wide measurement range. Specifically, when the Reynolds coefficient ranges from 2×104 to 7×106, the measurement range is up to 1:20.
◆Low pressure loss (about 1/4~1/2 of orifice flowmeter), it belongs to energy-saving flowmeter.
◆It supports flexible installation and can be installed horizontally, vertically and inclined at different angles according to the different process pipelines on site.
◆The anti-disturbance circuit and anti-vibration sensor head are adopted, which make it has certain anti-environmental vibration performance.
◆By using ultra-low power single chip microcomputer technology, a 3V10AH lithium battery can be used for more than five years.
The non-linearity of instrument coefficients is corrected by software to improve measurement accuracy
Using EEPROM to protect cumulative flow from power failure, the protection time is longer than 10 years.
This instrument can be widely used in the measurement flow of water supply and drainage pipelines, industrial circulation, sewage treatment, oil and chemical reagents, compressed air, saturated and superheated steam, natural gas and various media.