Drexelbrook Total Tank Level System

Drexelbrook Total Tank Level System
Drexelbrook Total Tank Level System
Ametek is a world leader in level measurement technology products.  The Ametek Drexelbrook Total Tank Level System is a state-of-the-art measurement instrument utilizing magnetostrictive technology to accurately determine total product level, interface level, and temperature in liquid tanks. Offered in either a stainless steel rigid, and flexible Kynar version, these probes are capable of working in tanks from as low as 2 feet up to 50 feet high.

Magnetostriction is one of many level technology options available to industrial users today. For liquid measurements, especially when a water interface exists, it unquestionably offers the most versatile and accurate solution on the market. Ametek now has an excellent solution to manage multiple variable measurements in storage tanks. Ametek Drexel Brook now offers the Total Tank Level Multi-variable Transmitter to measure both level and temperature with Modbus, 4 to 20 milliamp, and HART output capability.

The ability to measure and track various tank conditions in realtime is critical in today's process environments. The multi-variable capability of the Drexelbrook Total Tank Level System provides simultaneous data for total level, interface level, product temperature, water interface temperature total average temperature, and volume for all liquid components in the tank. Standard industrial level instruments utilizing guided wave capacitive or radar technologies provide 3 to 5 millimeter accuracy. Higher cost tank gauging technologies will provide 1 to 2 millimeter accuracy. Only magnetostrictive technology can provide superior sub 1 millimeter accuracy levels consistently under most process conditions. In addition, the Drexel Brook Total Tank Level System is fully compensated across the entire operating range of process temperatures, up to 257 degrees Fahrenheit.

One of the most challenging applications is the measurement of an interface level between two significantly different density liquids. The most common of these is oil and water. There are only a few technologies that claim to be able to make this measurement. Guided wave radar and magnetostriction are two of the most common. Guided wave radar technology is based on microwave pulses that are transmitted down a probe and are partly reflected by the product surface, as well as the interface level surface. In applications where both liquids have stabilized, guided wave radar technology can accurately determine both the product and interface level. If an emulsion layer forms between the two liquids this can significantly diminish the measured value, or even cause the complete loss of the signal. If this occurs, it is extremely difficult to maintain control of the process. Using a float based magnetostrictive technology, the measurement becomes straightforward. Both product and interface return signals are generated by the reflection of a magnetically induced strain on the measurement wire, which is embedded in the probe. Magnets are positioned on the probe based on their specific gravity matched to the liquids being measured. This ensures that the float will always maintain its position, both on the top liquid level, and at the interface position. The lower measurement signal remains unaffected by the formation of an emulsion. Comparing the two technologies clearly shows the advantage of magnetostrictive technology whenever emulsion layers are present. Guided wave radar can only be used to measure the overall level reliably under all conditions, while the Drexelbrook Total Tank Level System guarantees the continuous and accurate measurement of the overall level, and the interface, even under emulsion conditions.

The Drexelbrook Total Tank Level System easily integrates into existing control systems that have standard protocols, such as Modbus, 4 to 20 milliamp loop, or HART communications. Each instrument can beset up directly through the Ametek STExplorer software which can be downloaded free of charge. This makes installation and commissioning of the instrument easy. Drexelbrook's reliable magnetostrictive level probes have been installed in more than 100,000 systems worldwide. They are proven over years of grueling weather conditions and trusted by some of the largest companies in the world.

Please watch the video below for more information. To discuss a tank level application, contact Piping Specialties by visiting https://www.psi-team.com or call 800-223-1468.

Basics of Process Temperature Sensors: RTDs and Thermocouples

industrial thermocouple
Industrial thermocouples (Marsh Bellofram TCP)
Proper temperature sensor selection is key to getting useful and accurate data for maintaining control of a process. There are two main types of temperature sensors employed for industrial applications, thermocouple and resistance temperature detector (RTD). Each has its own set of features that might make it an advantageous choice for a particular application.

Thermocouples consist of a junction formed with dissimilar metal conductors. The contact point of the conductors generates a small voltage that is related to the temperature of the junction. There are a number of metals used for the conductors, with different combinations used to produce an array of temperature ranges and accuracy. A defining characteristic of thermocouples is the need to use extension wire of the same type as the junction wires, in order to assure proper function and accuracy.

Here are some generalized thermocouple characteristics.
  • Various conductor combinations can provide a wide range of operable temperatures (-200°C to +2300°C).
  • Sensor accuracy can deteriorate over time.
  • Sensors are comparatively less expensive than RTD.
  • Stability of sensor output is not as good as RTD.
  • Sensor response is fast due to low mass.
  • Assemblies are generally rugged and not prone to damage from vibration and moderate mechanical shock.
  • Sensor tip is the measuring point.
  • Reference junction is required for correct measurement.
  • No external power is required.
  • Matching extension wire is needed.
  • Sensor design allows for small diameter assemblies. 
RTDs
Industrial RTDs
(Marsh Bellofram TCP)
RTD sensors are comprised of very fine wire from a range of specialty types, coiled within a protective probe. Temperature measurement is accomplished by measuring the resistance in the coil. The resistance will correspond to a known temperature. 

Some generalized RTD attributes:
  • Sensor provides good measurement accuracy, superior to thermocouple.
  • Operating temperature range (-200° to +850°C) is less than that of thermocouple.
  • Sensor exhibits long term stability.
  • Response to process change can be slow.
  • Excitation current source is required for operation.
  • Copper extension wire can be used to connect sensor to instruments.
  • Sensors can exhibit a degree of self-heating error.
  • Resistance coil makes assemblies less rugged than thermocouples.
  • Cost is comparatively higher.
Each industrial process control application will present its own set of challenges regarding vibration, temperature range, required response time, accuracy, and more. Share your process temperature measurement requirements and challenges with a process control instrumentation specialist, combining your process knowledge with their product application expertise to develop the most effective solution.

What Are High Performance Butterfly Valves (HPBV)?

High Performance Butterfly Valves (HPBV)
High Performance Butterfly Valve
(Pratt Industrial)
Industrial process control applications can present stringent and challenging performance requirements for the physical equipment and components that comprise the process chain. The valves employed in fluid based operations need to be resistant to the impact of extreme fluid conditions, requiring careful design and selection consideration to assure proper performance and safety levels are maintained in a predictable way.

Industrial butterfly valves intended for extreme applications are generally referred to as high performance valves (HPBV). While there are plenty of published and accepted standards for industrial valves, one does not exist to precisely define what constitutes a high performance valve.

So, how do you know when to focus valve selection activities on high performance butterfly valves, as opposed to those rated for general purpose? There are a number of basic criteria that might point you in that direction:
  • Extreme media or environmental temperature or pressure
  • High pressure drop operation that may cause cavitation
  • Rapid or extreme changes to inlet pressure
  • Certain types or amounts of solids contained in the fluid
  • Corrosive media
Certainly, any of these criteria might be found in an application serviceable by a general purpose valve, but their presence should be an indicator that a closer assessment of the fluid conditions and commensurate valve requirements is in order. The key element for a process stakeholder is to recognize when conditions are contemplated that can exceed the capabilities of a general purpose valve, leading to premature failure in control performance or catastrophic failure that produces an unsafe condition. Once the possibility of an extreme or challenging condition is identified, a careful analysis of the range of operating conditions will reveal the valve performance requirements.

There are numerous manufacturers of high performance butterfly valves. Pratt Industrial manufactures high-quality resilient-seated, high performance, and triple offset butterfly valves. Construction materials include carbon steel and stainless steel. Their TE Series triple offset valve offers premium, zero-leakage seating capability even in severe service applications.

You can always get more information and discuss your special requirements with a valve specialist. They have application experience and access to technical resources that can help with selecting the right valve components to meet your severe service and high performance applications.

What Are Industrial Ball Valves?

Internal view of a ball valve
Internal view of a ball valve
(MOGAS)
Ball valves are defined by their body style, the five major styles being: Uni-body; 3-piece; split-body; top-entry; and welded body. They are further defined by the machined hole in their ball (also known as the port); the categories being "standard port" or "full port".

On a full port valve, the port is the same size as the pipeline, resulting in a better flow profile and no restriction or pressure drop. A full ported ball valve, with better flow coefficients, comes at a higher price. In many application they are necessary because a reduction in diameter, or the resulting change in flow, can be detrimental.

The reduction in a standard port valve is one pipe size smaller than the pipe connected to the valve, resulting in restricted flow and increased velocity through the valve.

2-piece and unibody ball valves
2-piece and unibody ball valves (Flo-Tite)
Standard port and full port valves are not usually recommended for throttling service due the a very
non-linear flow characteristic. Characterizing the port with a special shaped orifice can improve the valve linearity and provide good control. V-port ball valves incorporate a machined "V" in the seat around the outlet side of the valve. The "V" provides a more controllable flow pattern and is desirable when ball valves are used as control valves.

A cavity filled ball valve is used in applications where cleanliness or sanitary conditions exist. Any voids, gaps or spaces between the ball, seat and stem that allow bacteria or contaminates to accumulate are filled.  The proper cavity filler material is selected consistent with the process media, application and level of cleanliness required. Cavity fillers eliminate the spaces and voids where contaminants accumulate and provides easy "flushing" (cleaning) of the valve.

In a trunnion mounted ball valve, the valve stem is mechanically attached to the ball. Trunnion mounted valves are mostly used in applications on large diameter gas and oil pipelines and at high pressures.

Most ball valves however, are designed with a “floating ball” and not held mechanically in place by a trunnion. This allows the ball to be "pushed" slightly downstream and seal itself better against the seat. One advantage to this design is that a valve using a floating ball, and fitted with metal seats, can be used for "fire-safe" applications. This means that if the valve is subject to high temperatures, such as those presented in a fire, the "soft" part of the seat will melt away, and allow the ball to secure itself against the metal seat, and thus not allow material to pass and potentially feed the fire.

For best service life and optimum safety, please review your application with a qualified ball valve applications consultant prior to specifying an industrial ball valve.

Understanding Rack & Pinion Pneumatic Valve Actuators

Internal view of rack and pinion actuator.
Internal view of rack and pinion actuator (UniTorq)
Rack & Pinion actuators are designed for operating quarter-turn valves such as butterfly, plug, and ball valves or for actuating industrial or commercial dampers.

The rotational movement of a rack and pinion actuator is accomplished via linear motion and two gears. A circular gear, referred to a “pinion” engages the teeth of a linear gear “bar” referred to as the “rack”.

In a pneumatic actuator, pistons are attached to the rack. As air or spring power is applied the to piston, the rack is “pushed” inward or “pulled” outward. This dual direction linear movement is transferred to the rotary pinion gear providing bi-directional rotation.

Rack and Pinion Animation
Rack and Pinion Animation
Pneumatic actuators have cylinders with pistons and springs that provide the linear movement. When one side of the piston is pressurized with air, gas or oil, the pinion bearing turns in one direction. When the air, gas or oil from the pressure side is vented, a spring (spring-return actuators) may be used to rotate the pinion gear in the opposite direction. A “double acting” actuator does not use springs, instead using the air, gas or oil supply on the opposing side of the piston to turn the pinion gear in the opposite direction.

Pneumatic pneumatic rack and pinion actuators are compact and save space. They are reliable, durable and provide a good life cycle. Mechanical wear of the heads and seals are their primary disadvantage.

Most actuators are designed for 100-degree travel with clockwise and counterclockwise travel adjustment for open and closed positions. World standard ISO mounting pad are commonly available to provide ease and flexibility in direct valve installation.
Rack and Pinion Actuator
Rack and Pinion Actuator (UniTorq)
NAMUR mounting dimensions on actuator pneumatic port connections and on actuator accessory holes and drive shaft are also common design features to make adding pilot valves and accessories more convenient.

Feel free to contact Piping Specialties, Inc. at www.psi-team.com or 800-223-1468 with any questions you may have about valve actuation.

Instructional Video: Inserting K-Patents Generation 2.1 SAFE-DRIVE™ Process Refractometer PR-23-SD

This video is intended for individuals installing, commissioning, operating, and/ or servicing the K-Patents Safe-DriveTM Process Refractometer PR-23-SD, generation 2 model. The purpose of this video is to provide a quick guide for the above mentioned tasks in the form of K-Patents recommended best practices.

K-Patents SAFE-DRIVE™ design allows for safe and easy insertion and retraction of the sensor under full operating pressure without having to shut down the process.

Below the video is the document "Best Practices for the Safe-DriveTM Process Refractometer PR-23-SD Generation 2" for your convenience.

For more information, visit http://www.psi-team.com or call 800-223-1468.

VIDEO



DOCUMENT

Magnetic Flowmeters: Principles and Applications

Magnetic Flowmeter
Magnetic Flowmeter (Azbil)
Crucial aspects of process control include the ability to accurately determine qualities and quantities of materials. In terms of appraising and working with fluids (such as liquids, steam, and gases) the flowmeter is a staple tool, with the simple goal of expressing the delivery of a subject fluid in a quantified manner. Measurement of media flow velocity can be used, along with other conditions, to determine volumetric or mass flow. The magnetic flowmeter, also called a magmeter, is one of several technologies used to measure fluid flow.

In general, magnetic flowmeters are sturdy, reliable devices able to withstand hazardous environments while returning precise measurements to operators of a wide variety of processes. The magnetic flowmeter has no moving parts. The operational principle of the device is powered by Faraday's Law, a fundamental scientific understanding which states that a voltage will be induced across any conductor moving at a right angle through a magnetic field, with the voltage being proportional to the velocity of the conductor. The principle allows for an inherently hard-to-measure quality of a substance to be expressed via the magmeter. In a magmeter application, the meter produces the magnetic field referred to in Faraday's Law. The conductor is the fluid. The actual measurement of a magnetic flowmeter is the induced voltage corresponding to fluid velocity. This can be used to determine volumetric flow and mass flow when combined with other measurements.

The magnetic flowmeter technology is not impacted by temperature, pressure, or density of the subject fluid. It is however, necessary to fill the entire cross section of the pipe in order to derive useful volumetric flow measurements. Faraday's Law relies on conductivity, so the fluid being measured has to be electrically conductive. Many hydrocarbons are not sufficiently conductive for a flow measurement using this method, nor are gases.

Magmeters apply Faraday's law by using two charged magnetic coils; fluid passes through the magnetic field produced by the coils. A precise measurement of the voltage generated in the fluid will be proportional to fluid velocity. The relationship between voltage and flow is theoretically a linear expression, yet some outside factors may present barriers and complications in the interaction of the instrument with the subject fluid. These complications include a higher amount of voltage in the liquid being processed, and coupling issues between the signal circuit, power source, and/or connective leads of both an inductive and capacitive nature.

In addition to salient factors such as price, accuracy, ease of use, and the size-scale of the flowmeter in relation to the fluid system, there are multiple reasons why magmeters are the unit of choice for certain applications. They are resistant to corrosion, and can provide accurate measurement of dirty fluids ' making them suitable for wastewater measurement. As mentioned, there are no moving parts in a magmeter, keeping maintenance to a minimum. Power requirements are also low. Instruments are available in a wide range of configurations, sizes, and construction materials to accommodate various process installation requirements.

As with all process measurement instruments, proper selection, configuration, and installation are the real keys to a successful project. Share your flow measurement challenges of all types with a process measurement specialist, combining your process knowledge with their product application expertise to develop an effective solution.