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.

Providing New England Industry with Process Instrumentation, Valves, and Unsurpassed Service for Over 40 Years

PSI operates under one single mission: To provide specialty valves, instruments, control systems and mechanical products to industrial users throughout the Northeast, and to do so by providing unsurpassed customer service.

Covering the states of Maine, Vermont, Massachusetts, New Hampshire, Rhode Island, and Connecticut through offices located in Portland, Maine and Danvers, Connecticut, PSI is well situated to provide quick delivery, on-site services, and engineering support all through New England.

Piping Specialties, Inc. provides industrial valves, including ball, butterfly, gate, globe, safety relief, and control vales; and mechanical specialties including, steam traps, condensate recovery systems, steam water heaters, site level gauges, jet pumps, expansion joints, and modular pipe seals.

PSI Controls provides automated industrial and commercial valve packages that include quarter-turn and linear valves, pneumatic and electric actuators, limit switches and valve communications; and process instrumentation & controls including level, pressure, temperature and flow  instrumentation.

PSI Services provides installation of valve automation systems, valve repair, instrument repair, instrument calibration, turnkey systems and field support services.

Floating Roof Tank Spill Prevention

Floating Roof Tank Spill Prevention (Drexelbrook)

One of the most difficult and critical applications is measuring the high alarm or potential overfill condition on a floating roof tank containing liquid petroleum products such as crude oil or refined products such as fuel. It normally is comprised of a cylindrical steel tank equipped with an internal or external floating roof, that floats on the surface of the stored liquid. Floating roof tank systems are especially beneficial in eliminating the evaporative losses of the liquids. As opposed to a fixed roof tank there is no vapor space in the tank. This helps to reduce risk in highly explosive vapor environments. This is an extremely high cost of failure application, and one in which only the safest and most trusted products are accepted.

Drexelbrook's
Intellipoint

Safe operation of the tank farm relies on critical real time continuous level measurements of the liquids in the tank, as well as detecting when a high level condition exists. Products used in this application are typically required to meet the API 2350 Overfill Protection Standards, as well as SIL Safety Integrity Level performance standards to IEC 61508.

The challenges to reliably detect a high level condition on a floating roof tank are long sensor length requirements, and the variability of what is being measured. The floating roof may be dry in which case you need to detect the position of the physical metal roof. Or there may be a few inches of rain water or petroleum liquids on the roof. Measuring instruments need to determine very accurately, usually within a few millimeters, when the position of the floating roof has reached a high level alarm condition.

Drexelbrook's Intellipoint, with its unique floating roof probe, can accurately detect and alarm on the position of the floating roof or the presence of liquid under all these conditions. The safety Intellipoint is a SIL2 fully certified RF admittance point level switch with uncompromising reliability for the most demanding applications.  Drexelbrook has almost 60 years of RF admittance technology experience and is proud to offer this specialized product as the latest in its award-winning portfolio for the level market.

Product features include:

• Adjustable up to 15 feet, or 4.6 meters, to accurately control the alarm point. 
• A trip point accuracy of a few millimeters.
• Fully SIL2 certified to IEC61508. 
• Worldwide hazardous area approvals .
• Meets overfill protection standards API2350.
• A floating roof tank probe that is unique in the industry.

Refractometer Application for Wet Spinning of Alginate Fibers

Refractometer used for
wet spinning of alginate fiber.
(K-Patents) 

Alginates are biopolymers extracted from brown algae species such as seaweed. Extraction is performed from the harvested material by treatment with aqueous alkaline solutions. The extract is then filtered and the alginate salt is precipitated by the addition of calcium chloride or an acid. After purification, drying and milling, a water-soluble sodium alginate powder is produced. Alginates have found a variety of uses in different industries because of their unique properties. These materials have been extensively used in pharmaceutical applications as they are gel forming, non-toxic and highly absorbent.

The document below illustrates the use of industrial refractometers in the processing of Sodium Alginate. You can also download the full PDF of "Wet Spinning of Alginate Fibers" here.

Refractometer Application for Wet Spinning of Alginate Fibers from Piping Specialties, Inc and PSI Controls

Conval Clampseal Valve Seat Reassembly Instructions

Valve seat reassembly instructions for Conval Clampseal valve.

Conval Clampseal® Valves are much easier to renew than anything else on the market. This video is seventh and final video in a series demonstrating how to service Clampseal valves.

https://psi-team.com
800-223-1468

What is a Magnetic Level Gauge?

Magnetic Level Gauge (Penberthy)

Magnetic level gauges, also known as magnetic level indicators, are routinely used to provide a display of liquid level in tanks and other vessels. Their popularity stems from their high visibility from distances and non-invasive design which reduces the possibility of points and the risks of fugitive emissions.

"Mag Gauge" construction is fairly simple. A magnetic float, designed for the specific gravity of the material being measured, rides inside a vertical pipe on top of the process media. A gauge with magnetically coupled visual indicator is fastened to the pipe. As the media inside the pipe rises and falls, the visual indicator moves in the same fashion.

Magnetic level gauges are often employed in tandem with magnetostrictive, guided wave radar, or other measurement means to provide a reliable local display of liquid level, as well as an electrical signal that can be transmitted to recording instrumentation or controllers.

Magnetic level gauges features:

• Continuous level measurement
• Operable without electric power
• Direct visual tank fluid level indication, regardless of tank shape or profile.
• Wide range of operating temperature and pressure
• Breakage resistant construction
• Range of construction materials available to accommodate corrosive media
• Measuring indicators, switches, and transmitters mounted externally, without contacting the medium being measured.
• Low maintenance operation.
• Readable level indication from greater distance than glass sight gauges.
• Applicable to large fluid level ranges with a single instrument.

Magnetic level indicators are used widely in liquid level measurement and should be considered as a candidate for fulfilling those applications where the magnetic level gauge features fulfill the project requirements. There are many options available to customize the level indicator for each specific application. Share your application challenges with a product specialist, combining your process knowledge with their product application expertise to develop an effective solution.

Piping Specialties and PSI Controls

Piping Specialties was founded in 1975 with the mission of providing specialty valves and mechanical products and unsurpassed customer service to industrial users throughout the Northeast. Over the years our company has experienced steady, sustainable growth in both our customer base and product offerings. With offices in Danvers, MA and Portland, ME, we are geographically well-positioned to serve all of the Northeast.

PSI delivers our products and services through our 3 operating divisions:

• Piping Specialties: valves and mechanical specialties.
• PSI Controls: automated valves and process instrumentation & controls.
• PSI Services: valve automation, valve and instrument repair, calibration, and turnkey installation and field services.