The Azbil AX24R Reduced Bore Vortex Flowmeter

EXTENDED MEASURING RANGE FOR LOWER FLOW RATES

Much of the measuring range of a standard vortex flowmeter is at higher fluid velocities. Because of this, measurements at low flow conditions may be missed due to the low flow cutoff. To remedy this issue, users often install pipe reducers and a smaller than line size vortex meter to increase fluid velocities through the meter. The Azbil AX24R reduced bore vortex flowmeter has integrated reducing flanges, eliminating the need for separate pipe reducers and spool pieces. This integrated reduction extends the measuring range to capture lower flow rates.

CAPTURES STEAM FLOW IN BOTH HIGH AND LOW DEMAND SEASONS

Steam usage in heating systems can vary widely based on seasonal demands. These systems are commonly sized with the high demand season (colder weather) in mind, and little thought is given to the low demand season (warmer weather). This leads to a situation where steam flowmeters are oversized and may miss flow measurements at low flow conditions. AX24R reduced bore vortex flowmeters have an extended low flow measuring range, capturing both high and low demand seasons.

REDUCED INSTALLATION COSTS

Like most flowmeters, vortex flowmeters have requirements for unobstructed upstream and downstream piping lengths to ensure a proper flow profile through the meter. Adding pipe reducers adds cost and complexity to the piping design since those unobstructed piping lengths are required before and after the pipe reducers.

The AX24R reduced bore vortex flowmeter has integrated reducing flanges, eliminating the need for separate pipe reducers and spool pieces. Drastically reducing both the complexity and cost of the meter installation.

SAME FACE-TO-FACE DIMENSION AS A STANDARD VORTEX METER

AX24R reduced bore vortex flowmeters have the same face-to-face dimension as a standard AX24 flowmeter for pressure classes up to ANSI 600. So if process conditions change, the meter body size can be changed without any costly piping modifications. This is especially useful in project planning, as it allows for flexibility into the future.

For more information on the Azbil AX24R in New England, contact Piping Specialties / PSI Controls. Call 800-223-1468 or visit https://psi-team.com.

The Azbil AX Series of Vortex Inline Flow Meters

The AX Series of Vortex inline flowmeters measure flows of liquid, gas, and steam by measuring the rate at which vortices are alternately shed from a bluff body; this rate has been shown to be directly proportional to the flow velocity.

As flow passes a bluff body in the stream, vortices create pressure differentials which are measured by a piezoelectric crystal sensor, which converts these pulses into electrical signals. The meter uses an all-welded sensor design to create a strong unit and minimize potential leakage.

The Azbil AX Series can be configured to measure anything from simple volumetric flow of liquids and saturated steam up through multivariable measurements, including mass flow rate, pressure, temperature and density of liquids and steam.

Insertion style vortex meters measure fl ow by detecting the local velocity at a strategically located position within the pipe. Using local velocity, calculated by measuring the rate at which vortices are alternately shed from a bluff body within the sensor, the Azbil AX2300 uses parameters such as fluid type, pipe size, and Reynolds number to calculate accurate measurements.

Download the Azbil AX Series Vortex Flow Meter brochure here.

Azbil AX Series Vortex Flow Meters from Piping Specialties, Inc and PSI Controls

Operating Principles and Application of Vortex Flowmeters

Animation of vortices*

To an untrained ear, the term "vortex flowmeter" may conjure futuristic, potentially Star Wars inspired images of a hugely advanced machine meant for opening channels in warp-space. In reality, vortex flowmeters are application specific, industrial grade instruments designed to measure an important element of a fluid process control operation: flow rate.

Vortex flowmeters operate based on a scientific principle called the von Karman effect, which generally states that a fluid flow will alternately shed vortices when passing by a solid body. "Vortices" is the plural form of vortex, which is best described as a whirling mass, notably one in which suction forces operate, such as a whirlpool. Detecting the presence of the vortices and determining the frequency of their occurrence is used to provide an indication of fluid velocity. The velocity value can be combined with temperature, pressure, or density information to develop a mass flow calculation. Vortex flowmeters exhibit high reliability, with no moving parts, serving as a useful tool in the measurement of liquid, gas, and steam flow.

Photograph of vortices **

While different fluids present unique challenges when applying flowmeters, steam is considered one of the more difficult to measure due to its pressure, temperature, and potential mixture of liquid and vapor in the same line. Multiple types of steam, including wet steam, saturated steam, and superheated steam, are utilized in process plants and commercial installations, and are often related to power or heat transfer. Several of the currently available flow measurement technologies are not well suited for steam flow applications, leaving vortex flowmeters as something of a keystone in steam flow measurement.

Rangeability, defined as a ratio of maximum to minimum flow, is an important consideration for any measurement instrument, indicating its ability to measure over a range of conditions. Vortex flowmeter instruments generally exhibit wide rangeability, one of the positive aspects of the technology and vortex based instruments.

The advantages of the vortex flowmeter, in addition to the aforementioned rangeability and steam-specific implementation, include available accuracy of 1%, a linear output, and a lack of moving parts. It is necessary for the pipe containing the measured fluid to be completely filled in order to obtain useful measurements.

Vortex flowmeter
(Azbil)

Applications where the technology may face hurdles include flows of slurries or high viscosity liquids. These can prove unsuitable for measurement by the vortex flowmeter because they may not exhibit a suitable degree of the von Karman effect to facilitate accurate measurement. Measurements can be adversely impacted by pulsating flow, where differences in pressure from the relationship between two or more compressors or pumps in a system results in irregular fluid flow.

When properly applied, the vortex flowmeter is a reliable and low maintenance tool for measuring fluid flow. Frequently, vortex flow velocity measurement will be incorporated with the measurement of temperature and pressure in an instrument referred to as a multivariable flowmeter, used to develop a complete measurement set for calculating mass flow.

Whatever your flow measurement challenges, share them with a flow instrument specialist, combining your process knowledge with their product and technology expertise to develop effective solutions.

* Animation of vortex creation credit Cesareo de La Rosa Siqueira via Wikipedia.
** Photograph of vortices credit Jürgen Wagner via Wikipedia.