In selecting a valve for use plenty of characteristics must be suitable for your desired application. Readers recently asked Béla Lipták some questions regarding control valves and their characteristics. Some of the questions and answers are presented below. The complete list can be found at the link below.
What are the definitions of wide and small ranges in terms of flow turndown?
A control loop will be stable if its gain does not change with variations in the load. The loop gain is the product of four gains (process, controller, sensor, valve) and, ideally, it should stay constant at about 0.5. If the process gain varies with load and the sensor and controller gains are constant, the ideal valve characteristic is one that will compensate for the variation in process gain, so that if the process gain rises with load, the valve gain drops (equal percentage); if the process gain drops with load, the valve gain rises (quick opening) and if the process gain remains constant, the valve gain should also be constant (linear).
How would I go about measuring flow of hydrocarbons with 1% sand by mass included?
Either Coriolis or vortex can wear at a rate proportional to the percentage of sand in the flow, and both meters could have a short lives. Sharp-edge orifices are similarly vulnerable. The choice is affected by flow rate and pipe size.
I would worry about any Coriolis flowmeter with a relatively thin metal wall. Magnetic, ultrasonic and flow nozzles have been recommended. With a sufficiently high flow rate, an elbow meter will also work. Any DP meter might need a chemical seal or liquid purge to avoid plugging.
Click here for the full article on Control Global.
Maintenance – what is it good for? Some companies invest the very least, or in some cases no time or funds at all in shutting down equipment for servicing. Other businesses have robust maintenance programs, making it part of their regular working schedule. Which is better? The following will discuss some of the reasons why flow meter calibration should be included in your operations.
For Long Life
Keeping equipment in excellent working order extends its life. When components are well-maintained, it saves your business money in the long run. The following are some of the industries that rely on flow meter calibration:
General Industry
Chemical and Petrochemical
Energy
Laboratory
Aerospace and Aviation
Pharmaceutical and Food
In each of the above sectors, well-made equipment and infrastructure can last many years beyond the manufacturer’s warranty, but because fabricated parts do not take care of themselves, they must be maintained.
To Promote Consistency
Each industry produces a product that consumers or businesses rely on. Take the energy industry as an example. Refineries and processing plants continuously produce a product that meets certain specifications. Flow meter calibration is one of the ways they can continue to provide a product of the same grade, octane or viscosity. Anything inconsistent in this industry can lead to machine failure or even dangerous outcomes.
To Meet Regulation
As you can tell from the industry list above, each field comes with its own set of regulations. The pharmaceutical sector is regulated by the FDA, and any failure to meet standards can result in consequences that end in significant profit losses and sometimes even a close of the business. There is no need to fear regulators if your operations are under compliance and in good working order.
For the Safety of All
Passenger airlines have gone out of business because of safety breaches, and bankruptcy is not even the big issue. Safety does not so much have to do with business as it does with lives. If a cargo plane goes down because of preventable equipment failure and a couple of lives are lost, it may not make as many headlines, but it is still unacceptable.
Why Let an Outside Firm Handle Calibration?
The best servicers do everything they can to prepare your flow meters for use in your facility. This usually means:
Testing and calibrating units under steady state flow
Using recognized standards and measurements rather than standards created “in house”
Controlling environmental factors such as temperature and pressure to match as closely as possible that of where the equipment normally operates
Outside firms perform rigorous inspections on units that can improve calibration results. They are capable of handling industrial cleaning such as removing mineral buildup or corrosion without damaging the equipment. If results still are not satisfactory, they can troubleshoot at a level that exceeds most persons outside of the calibration industry.
Maintenance can extend the life of flow meters, prevent unnecessary repairs, and improve safety, quality and consistency. A flow meter calibration company should be able to handle servicing for any brand of unit you may own. No matter the industry you work in, it is clear that keeping equipment in great working order is an investment that is worth every penny.
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Human voices are unique to the individual and current technology has been used to restrict access to authorized personnel using voices as authentication. Now by identifying the voices of devices on control networks a possible new defense would filter legitimate signals and attacks.
“We have developed fingerprinting techniques that work together to protect various operations of the power grid to prevent or minimize spoofing of packets that could be injected to produce false data or false control commands into the system. This is the first technique that can passively fingerprint different devices that are part of critical infrastructure networks. We believe it can be used to significantly improve the security of the grid and other networks.” -Raheem Beyah Georgia Institute of Technology
The security techniques take advantage of the individual physical properties of each unique device. Security devices listening to the grid would differentiate devices that were authenticated to the grid, and identify illegitimate “noise” within the system. Furthermore, the system can use simple physics to flush out spoofing attempts. Depending on the physical configuration of breakers and valves, opening and closing procedures take a minimum amount of time. If a device gets a signal to open or close too soon after the last signal security staff would be notified of a possible attack.
Because they also include devices with measurable physical properties, Beyah believes the approach could have broad application to securing industrial control systems used in manufacturing, oil and gas refining, wastewater treatment and other industries.
Click here for the full article from Control Engineering.
Fluid pumps are specifically designed to optimize the flow of fluids through the systems they are connected to with as little non-condensable gases as possible. Air trapped in the fluids can cause cavitation at higher flow rates that damages pump internals as well as pipe seals and joints. For these reasons the proper depth to submerge pumps is pivotal to prevent as much air from flowing through a pump.
As the velocity of the fluid flowing through a pipe increases the depth required for a pump pushing the same rate of flow increases. Because velocity increases as pipe diameter decreases and flow rate remains static, if the same pump is connected to a smaller pipe, the input source for the pump needs to be deeper to prevent vortices from forming. If the source tank is too shallow to allow for this minimum submergence other methods like suction bells and barriers can be introduced to lengthen the travel distance of the fluid to the suction inlet of the pump.
As a general guideline, 2 percent free air will reduce pump flow by 10 percent, and 4 percent air will reduce the flow by more than 40 percent. The average pump will likely fail to operate at 14 percent air entrainment. Some pump designs that use vortex impellers, recessed impellers, separation chambers or air escapes can handle air entrainment up to 24 percent.
The recommended suction velocity for pumps is between 5 and 8 feet per second, with a suggested maximum of 6 feet per second unless suspended solids or fluid characteristics demand faster flow rates.
There are many flow meter variations out there, and each application requires a different style of meter. Depending on the fluid being measured each style of flow meter may be more suited to that situation. Everything from the viscosity to the potential contaminants plays a part in choosing the perfect flow meter for your needs.
Accuracy Coriolis flow meters are highly accurate, but may impinge the flow of fluids through the pipeline.
Consistency Nutating disk flow meters are simple to replace, but may need repeated calibrations as parts wear down.
Minimal Flow Restriction Electromagnetic flow meters do not block or reduce flow, but can be costly to maintain.
Click here for the full article from Chemical Processing.com.
During the processing of natural gas liquid ethane is pumps from 28 bar vessels to 76 bar vessels, and while under normal temperatures this can be done easily, Texas summers regularly reach temperatures where ethane vaporizes and creates product loss. Most seals for these systems use a liquid-lubricated seal, but under varying pressures these can warp and leak. Different variations of this type of seal use an inert gas between one or more pressurized faces to prevent leaks, but once the liquid reaches a higher vapor pressure the now gas breaches the seal.
Dry gas seals are simple albeit unconventional in liquid pumping situations. Seals are normally designed for non-contact operation, meaning any turning, ratcheting, or other operating situations can cause wear and eventual failure. Dry gas seals feature a crystalline layer simulating natural diamond to resist chipping and flaking. Furthermore by using an inert gas as the holding pressure, any vaporized ethane must combat a higher pressure to escape.
The increased structural resilience and absence of mechanical contact make these types of seals longer lasting, up to 5 years rather than 3 weeks in this circumstance.
Click here for the full article on Pumps & Systems.
Human-machine interfaces are the terminals we use to interact with the digital world. In industrial applications these are the monitors on the plant floor that allow informed, safer choices. Developers and users continue to improve HMIs and apply them in newer environments.
In dairy processing acilities, incoming milk is chilled rapidly to 4° C and distributed to various silos for different end products. Each product has different tolerance during processing, and HMIs display this to plant operators in real-time for analysis and decision making. New models of HMIs and monitoring sensors have standardized these silos with new features like alarms for high or low temperatures as well as flow meters and float switches for distribution data, batch reports, and overflow warnings. Some new features can control pumps, and agitators for each individual silo as well.
Click here for the full article on Control Global.
The VEGAPULS 64 is a contactless level transmitter that uses radar to detect the level of a container up to 30 meters away with an accurancy of +/- mm. This level of accuracy is unparalleled and due in fact to a tighter beam angle. Other comparable radar liquid level transmitters have an average beam angle of 10°, but the VEGAPULS 64 has a beam angle of 3° allowing for better readings.
The new radar level sensor VEGAPULS 64 is not only ideal for wide use in the chemical and petroleum sectors, but also in the pharmaceutical and food industries, because of its hygienic materials and design. The relevant approvals for this sector, such as 3A and EHDEG, are available at launch. Thanks to its small antenna – the diameter of the smallest version is no larger than a 1-euro coin – it results in very compact process fittings, which means the sensor can offer an interesting alternative for confined spaces in small vessels.
Click here for the full article on Control Engineering.
