ifm Flow Switches and Meters

In almost all fields of process and plant engineering liquids or gases are used. For coolant and lubricant supply of plant and machinery, ventilation of installations and buildings and the processing of products. In case of no flow of these media considerable damage and downtime may result. Therefore it is important to monitor these media. In modern installations electronic flow monitors are used for this purpose. They work without wear and tear and without mechanical components. This guarantees reliable monitoring even in case of difficult media over a long period.

ifm, a leading manufacturer of industrial sensors and controls, offers a complete line of flow switches and meters.

Direct or remote mount:
  • The SI flow switch mounts directly in process
  • The SR and SN control monitors and sensing probes offer a modular and remote alternative
Mount in-line:
  • The SM magmeter monitors conductive media up to 26 gpm
  • The SU ultrasonic flow meter monitors water, oil and glycol
  • The SQ flow meter measure small dosing quantities
  • The SD flow meter monitors air and gas leaks
  • The SL air flow switch monitors ventilation systems
Check out the video below for more information on ifm flow sensors. Thanks for watching.

Understanding the Chemical Recovery Processes in Pulp & Paper Mills

chemical reclaim pulp and paper process
Figure 1
The kraft process is the dominant pulping process in the United States, accounting for approximately 85 percent of all domestic pulp production. The soda pulping process is similar to the kraft process, except that soda pulping is a non-sulfur process. One reason why the kraft process dominates the paper industry is because of the ability of the kraft chemical recovery process to recover approximately 95 percent of the pulping chemicals and at the same time produce energy in the form of steam. Other reasons for the dominance of the kraft process include its ability to handle a wide variety of wood species and the superior strength of its pulp.

The production of kraft and soda paper products from wood can be divided into three process areas:
  1. Pulping of wood chips
  2. Chemical recovery
  3. Product forming (includes bleaching)
The relationship of the chemical recovery cycle to the pulping and product forming processes is
chemical reclaim pulp and paper process
Figure 2
shown in Figure 1. Process flow diagrams of the chemical recovery area at kraft and soda pulp mills are shown in Figures 1 and 2, respectively.

The purpose of the chemical recovery cycle is to recover cooking liquor chemicals from spent
cooking liquor. The process involves concentrating black liquor, combusting organic compounds, reducing inorganic compounds, and reconstituting cooking liquor.

Cooking liquor, which is referred to as "white liquor, is an aqueous solution of sodium hydroxide (Na01) and sodium sulfide (Na2S) that is used in the pulping area of the mill. In the pulping process, white liquor is introduced with wood chips into digesters, where the wood chips are "cooked" under pressure. The contents of the digester are then discharged to a blow tank, where the softened chips are disintegrated into fibers or "pulp. The pulp and spent cooking liquor are subsequently separated in a series of brown stock washers: Spent cooking liquor, referred to as "weak black liquor, from the brown stock washers is routed to the chemical recovery area. Weak black liquor is a dilute solution (approximately 12 to 15 percent solids) of wood lignins, organic materials, oxidized inorganic compounds (sodium sulfate (Na2SO4), sodium carbonate (Na2003)), and white liquor (Na2S and Na0H).

In the chemical recovery cycle, weak black liquor is first directed through a series of multiple-effect evaporators (MEE's) to increase the solids content to about 50 percent. The "strong. (or "heavy") black liquor from the MEE's is then either oxidized in the BLO system if it is further concentrated in a DCE or routed directly to a concentrator (NDCE). Oxidation of the black liquor prior to evaporation in a DCE reduces emissions of TRS compounds, which are stripped from the black liquor in the DCE when it contacts hot flue gases from the recovery furnace. The solids content of the black liquor following the final evaporator/concentrator typically averages 65 to 68 percent.

Concentrated black liquor is sprayed into the recovery furnace, where organic compounds are combusted, and the Na2SO4 is reduced to Na2S. The black liquor burned in the recovery furnace has a high energy content (13,500 to 15,400 kilojoules per kilogram (kJ/kg) of dry solids (5,800 to 6,600 British thermal units per pound {Btu/lb} of dry solids)), which is recovered as steam for process requirements, such as cooking wood chips, heating and evaporating black liquor, preheating combustion air, and drying the pulp or paper products. Particulate matter (PM) (primarily Na2SO4) exiting the furnace with the hot flue gases is collected in an electrostatic precipitator (ESP) and added to the black liquor to be fired in the recovery furnace. Additional makeup Na2SO4, or "saltcake," may also be added to the black liquor prior to firing.

Molten inorganic salts, referred to as "smelt," collect in a char bed at the bottom of the furnace. Smelt is drawn off and dissolved in weak wash water in the SDT to form a solution of carbonate salts called "green liquor," which is primarily Na2S and Na2CO3. Green liquor also contains insoluble unburned carbon and inorganic Impurities, called dregs, which are removed in a series of clarification tanks.

Decanted green liquor is transferred to the causticizing area, where the Na2CO3 is converted to NaOH by the addition of lime (calcium oxide [Ca0]). The green liquor is first transferred to a slaker tank, where Ca0 from the lime kiln reacts with water to form calcium hydroxide (Ca(OH)2). From the slake, liquor flows through a series of agitated tanks, referred to as causticizers, that allow the causticizing reaction to go to completion (i.e., Ca(OH)2 reacts with Na2CO3 to form NaOH and CaCO3).

The causticizing product is then routed to the white liquor clarifier, which removes CaCO3 precipitate, referred to as "lime mud." The lime mud, along with dregs from the green liquor clarifier, is washed in the mud washer to remove the last traces of sodium. The mud from the mud washer is then dried and calcined in a lime kiln to produce "reburned" lime, which is reintroduced to the slaker. The mud washer filtrate, known as weak wash, is used in the SDT to dissolve recovery furnace smelt. The white liquor (NaOH and Na2S) from the clarifier is recycled to the digesters in the pulping area of the mill.

At about 7 percent of kraft mills, neutral sulfite semi-chemical (NSSC) pulping is also practiced. The NSSC process involves pulping wood chips in a solution of sodium sulfite and sodium bicarbonate, followed by mechanical de-fibrating. The NSSC and kraft processes often overlap in the chemical recovery loop, when the spent NSSC liquor, referred to as "pink liquor," is mixed with kraft black liquor and burned in the recovery furnace. In such cases, the NSSC chemicals replace most or all of the makeup chemicals. For Federal regulatory purposes, if the weight percentage of pink liquor solids exceeds 7 percent of the total mixture of solids fired and the sulfidity of the resultant green liquor exceeds 28 percent, the recovery furnace is classified as a "cross-recovery furnace.'" Because the pink liquor adds additional sulfur to the black liquor, TRS emissions from cross recovery furnaces tend to be higher than from straight kraft black liquor recovery furnaces.

With over 70 years experience, Thompson Equipment Company, Inc. (TECO) provides specialized instrumentation, magnetic flow meters, and re-manufactured process instruments used in the pulp and paper industry. For information on process control instruments, valves, or service or calibration, visit http://www.teco-inc.com or call 800-528-8997.

Understanding Why Cavitation and Flashing are Bad for Control Valves and Pumps

cavitation
Cavitation is caused by bubbles collapsing asymmetrically
at very high speeds, producing extremely high
pressures in very small areas. 
Fluid passing through a control valve experiences changes in velocity as it enters the narrow constriction of the valve trim (increasing velocity) then enters the widening area of the valve body downstream of the trim (decreasing velocity). These changes in velocity result in the fluid molecules’ kinetic energies changing as well. In order that energy be conserved in a moving fluid stream, any increase in kinetic energy due to increased velocity must be accompanied by a complementary decrease in potential energy, usually in the form of fluid pressure. This means the fluid’s pressure will fall at the point of maximum constriction in the valve (the vena contracta, at the point where the trim throttles the flow) and rise again (or recover) downstream of the trim.

If fluid being throttled is a liquid, and the pressure at the vena contracta is less than the vapor pressure of that liquid at the flowing temperature, the liquid will spontaneously boil. This is the phenomenon of flashing. If, however, the pressure recovers to a point greater than the vapor pressure of the liquid, the vapor will re-condense back into liquid again. This is called cavitation.

As destructive as flashing is to a control valve, cavitation is worse. When vapor bubbles re-condense into liquid they often do so asymmetrically, one side of the bubble collapsing before the rest of the bubble. This has the effect of translating the kinetic energy of the bubble’s collapse into a high-speed “jet” of liquid in the direction of the asymmetrical collapse. These liquid “microjets” have been experimentally measured at speeds up to 100 meters per second (over 320 feet per second). What is more, the pressure applied to the surface of control valve components in the path of these microjets is intense. Each microjet strikes the valve component surface over a very small surface area, resulting in a very high pressure (P = F/A ) applied to that small area. Pressure estimates as high as 1500 newtons per square millimeter (1.5 giga-pascals, or about 220000 PSI!) have been calculated for cavitating control valve applications involving water.

Watch the video below to better understand the impact of cavitation on a process flow system.

Basics of Variable Area Flowmeters

Variable Area Flowmeter (Rotameter)
Rotameter (ABB)
Flowmeters are a class of devices or instruments used to measure rate of fluid flow. Flow measurement stands as a vital input to many process operations across almost every industry. Applications can range from precise measurement of very small gas flows to oil or water flows through large diameter piping systems. There are a number of technologies employed for measuring fluid flow, each with attributes of design, performance, or cost that can make them an advantageous choice for a particular application.

Variable-area flowmeters are designed to measure flow using a precisely fabricated obstruction in the flow path that is repositioned in a tapered flow tube by changes in fluid flow.

Variable Area Flowmeter (Rotameter)
Rotameter (ABB
A rotameter is a flow indicator consisting of a tapered tube containing a plummet. The plummet is generally a solid object and sometimes referred to as a float. Rotameters rely on gravity as part of their operating principle, so the instrument must be installed such that the inlet is at the bottom and fluid flows directly upward through the tapered tube. As fluid flows through the tube, a pressure differential develops across the plummet. This creates an upward force on the plummet, moving the plummet in the direction of the flow. The flow area around the plummet increases as it moves from the narrow portion of the flow tube to a wider portion up the measurement scale. As the available flow space around the plummet increases, the upward force on it decreases. Eventually, the equalization between the pressure force and the weight of the plummet occurs and the float stops moving. The flow rate is indicated by the plummet's position relative to a pre-calibrated scale printed along the length of the tube. The same type of system can be used to measure liquid or gas flow, with the rotameter being specifically calibrated for the fluid to be measured. It is common to employ a rotameter with an integral needle valve as a metering device for delivering a precise fixed flow of a fluid into a process.

These devices are generally inexpensive and easy to apply. Key application considerations include a vertical installation orientation, matching the rotameter to the fluid, and providing physical access to read the indicated flow.

Industries use rotameters primarily as indicating devices. Rotameters enjoy a wide range of applications throughout research and manufacturing processes. Share your flow measurement challenges with instrumentation specialists, combining your own process knowledge and experience with their product application expertise to develop effective solutions.

Industrial Valve Basics: Rotary Ball Valves

Ball valve
Cut-away view of ball
valve components:

1) Body
2) Seat
3) Foating ball 
4) Lever handle 
5) Stem

(Image courtesy of Wikipedia)
A ball valve is a rotational motion valve that uses a ball-shaped disk to stop or start fluid flow. The ball, performs the same function as the disk in the globe valve. When the valve handle is turned to open the valve, the ball rotates to a point where the hole through the ball is in line with the valve body inlet and outlet. When the valve is shut, the ball is rotated so that the hole is perpendicular to the flow openings of the valve body and the flow is stopped.

Most ball valve actuators are of the quick-acting type, which require a 90° turn of the valve handle to operate the valve. Other ball valve actuators are planetary gear-operated. This type of gearing allows the use of a relatively small handwheel and operating force to operate a fairly large valve.

Some ball valves have been developed with a spherical surface coated plug that is off to one side in the open position and rotates into the flow passage until it blocks the flowpath completely. Seating is accomplished by the eccentric movement of the plug. The valve requires no lubrication and can be used for throttling service.

Advantages

A ball valve is generally the least expensive of any valve configuration and has low maintenance costs. In addition to quick, quarter turn on-off operation, ball valves are compact, require no lubrication, and give tight sealing with low torque.

Disadvantages

Conventional ball valves have relatively poor throttling characteristics. In a throttling position, the partially exposed seat rapidly erodes because of the impingement of high velocity flow.

Typical Ball Valve
Typical Ball Valve (click for larger view).

Port Patterns

Ball valves are available in the venturi, reduced, and full port pattern. The full port pattern has a ball with a bore equal to the inside diameter of the pipe.

Valve Materials


Balls are usually metallic in metallic bodies with trim (seats) produced from elastomeric (elastic materials resembling rubber) materials. Plastic construction is also available.

The resilient seats for ball valves are made from various elastomeric material. The most common seat materials are teflon (TFE), filled TFE, Nylon, Buna-N, Neoprene, and combinations of these materials. Because of the elastomeric materials, these valves cannot be used at elevated temperatures. Care must be used in the selection of the seat material to ensure that it is compatible with the materials being handled by the valve.

Ball Valve Stem Design

The stem in a ball valve is not fastened to the ball. It normally has a rectangular portion at the ball end which fits into a slot cut into the ball. The enlargement permits rotation of the ball as the stem is turned.

Ball Valve Bonnet Design

A bonnet cap fastens to the body, which holds the stem assembly and ball in place. Adjustment of the bonnet cap permits compression of the packing, which supplies the stem seal. Packing for ball valve stems is usually in the configuration of die-formed packing rings normally of TFE, TFE-filled, or TFE-impregnated material. Some ball valve stems are sealed by means of O-rings rather than packing.

Ball Valve Position

Some ball valves are equipped with stops that permit only 90° rotation. Others do not have stops and may be rotated 360°. With or without stops, a 90° rotation is all that is required for closing or opening a ball valve.

The handle indicates valve ball position. When the handle lies along the axis of the valve, the valve is open. When the handle lies 90° across the axis of the valve, the valve is closed. Some ball valve stems have a groove cut in the top face of the stem that shows the flowpath through the ball. Observation of the groove position indicates the position of the port through the ball. This feature is particularly advantageous on multiport ball valves.


For more information about any style industrial valve, contact TECO at 800-528-8997 or visit http://www.teco-inc.com.

Industrial Valve Basics: Linear Valves


Parts of a valve
Fig. 1 - Parts of a valve.
A valve is a mechanical device that controls the flow of fluid and pressure within a system or process. A valve controls system or process fluid flow and pressure by performing any of the following functions: 1) Stopping and starting fluid flow; 2) varying (throttling) the amount of fluid flow; 3) controlling the direction of fluid flow; 4) regulating downstream system or process pressure; 5) relieving component or piping over pressure.

There are many valve designs and types that satisfy one or more of the functions identified above. A multitude of valve types and designs safely accommodate a wide variety of industrial applications.

Regardless of type, all valves have the following basic parts: the body, bonnet, trim (internal elements), actuator, and packing. The basic parts of a valve are illustrated in Figure 1.





Valve Body


The body, sometimes called the shell, is the primary pressure boundary of a valve. It serves as the principal element of a valve assembly because it is the framework that holds everything together.

The body, the first pressure boundary of a valve, resists fluid pressure loads from connecting piping. It receives inlet and outlet piping through threaded, bolted, or welded joints.

Valve bodies are cast or forged into a variety of shapes. Although a sphere or a cylinder would theoretically be the most economical shape to resist fluid pressure when a valve is open, there are many other considerations. For example, many valves require a partition across the valve body to support the seat opening, which is the throttling orifice. With the valve closed, loading on the body is difficult to determine. The valve end connections also distort loads on a simple sphere and more complicated shapes. Ease of manufacture, assembly, and costs are additional important considerations. Hence, the basic form of a valve body typically is not spherical, but ranges from simple block shapes to highly complex shapes in which the bonnet, a removable piece to make assembly possible, forms part of the pressure- resisting body.

Narrowing of the fluid passage (venturi effect) is also a common method for reducing the overall size and cost of a valve. In other instances, large ends are added to the valve for connection into a larger line.

Valve Bonnet


The cover for the opening in the valve body is the bonnet. In some designs, the body itself is split into two sections that bolt together. Like valve bodies, bonnets vary in design. Some bonnets function simply as valve covers, while others support valve internals and accessories such as the stem, disk, and actuator.

The bonnet is the second principal pressure boundary of a valve. It is cast or forged of the same material as the body and is connected to the body by a threaded, bolted, or welded joint. In all cases, the attachment of the bonnet to the body is considered a pressure boundary. This means that the weld joint or bolts that connect the bonnet to the body are pressure-retaining parts.

Valve bonnets, although a necessity for most valves, represent a cause for concern. Bonnets can complicate the manufacture of valves, increase valve size, represent a significant cost portion of valve cost, and are a source for potential leakage.

Valve Trim


The internal elements of a valve are collectively referred to as a valve's trim. The trim typically includes a disk, seat, stem, and sleeves needed to guide the stem. A valve's performance is determined by the disk and seat interface and the relation of the disk position to the seat.

Because of the trim, basic motions and flow control are possible. In rotational motion trim designs, the disk slides closely past the seat to produce a change in flow opening. In linear motion trim designs, the disk lifts perpendicularly away from the seat so that an annular orifice appears.


Disk and Seat


For a valve having a bonnet, the disk is the third primary principal pressure boundary. The disk provides the capability for permitting and prohibiting fluid flow. With the disk closed, full system pressure is applied across the disk if the outlet side is depressurized. For this reason, the disk is a pressure-retaining part. Disks are typically forged and, in some designs, hard-surfaced to provide good wear characteristics. A fine surface finish of the seating area of a disk is necessary for good sealing when the valve is closed. Most valves are named, in part, according to the design of their disks.

The seat or seal rings provide the seating surface for the disk. In some designs, the body is machined to serve as the seating surface and seal rings are not used. In other designs, forged seal rings are threaded or welded to the body to provide the seating surface. To improve the wear-resistance of the seal rings, the surface is often hard-faced by welding and then machining the contact surface of the seal ring. A fine surface finish of the seating area is necessary for good sealing when the valve is closed. Seal rings are not usually considered pressure boundary parts because the body has sufficient wall thickness to withstand design pressure without relying upon the thickness of the seal rings.


Stem


The stem, which connects the actuator and disk, is responsible for positioning the disk. Stems are typically forged and connected to the disk by threaded or welded joints. For valve designs requiring stem packing or sealing to prevent leakage, a fine surface finish of the stem in the area of the seal is necessary. Typically, a stem is not considered a pressure boundary part.

Connection of the disk to the stem can allow some rocking or rotation to ease the positioning of the disk on the seat. Alternately, the stem may be flexible enough to let the disk position itself against the seat. However, constant fluttering or rotation of a flexible or loosely connected disk can destroy the disk or its connection to the stem.

Two types of valve stems are rising stems and nonrising stems. Illustrated in Figures 2 and 3, these two types of stems are easily distinguished by observation. For a rising stem valve, the stem will rise above the actuator as the valve is opened. This occurs because the stem is threaded and mated with the bushing threads of a yoke that is an integral part of, or is mounted to, the bonnet.

There is no upward stem movement from outside the valve for a nonrising stem design. For the nonrising stem design, the valve disk is threaded internally and mates with the stem threads.

Rising Stems
Figure 2 - Rising Stems

Nonrising Stems
Figure 3 -Non-rising Stems

Valve Actuator


The actuator operates the stem and disk assembly. An actuator may be a manually operated handwheel, manual lever, motor operator, solenoid operator, pneumatic operator, or hydraulic ram. In some designs, the actuator is supported by the bonnet. In other designs, a yoke mounted to the bonnet supports the actuator.

Except for certain hydraulically controlled valves, actuators are outside of the pressure boundary. Yokes, when used, are always outside of the pressure boundary.

Valve Packing


Most valves use some form of packing to prevent leakage from the space between the stem and the bonnet. Packing is commonly a fibrous material (such as flax) or another compound (such as teflon) that forms a seal between the internal parts of a valve and the outside where the stem extends through the body.

Valve packing must be properly compressed to prevent fluid loss and damage to the valve's stem. If a valve's packing is too loose, the valve will leak, which is a safety hazard. If the packing is too tight, it will impair the movement and possibly damage the stem.

Please contact Thompson Equipment (TECO) with any valve repair, valve automation, or new valve requirement. You can visit TECO at http://www.teco-inc.com or call 800-528-8997.

Process Instrument Calibration

Process Instrument CalibrationCalibration is an essential part of keeping process measurement instrumentation delivering reliable and actionable information. All instruments utilized in process control are dependent on variables which translate from input to output. Calibration ensures the instrument is properly detecting and processing the input so that the output accurately represents a process condition. Typically, calibration involves the technician simulating an environmental condition and applying it to the measurement instrument. An input with a known quantity is introduced to the instrument, at which point the technician observes how the instrument responds, comparing instrument output to the known input signal.

Even if instruments are designed to withstand harsh physical conditions and last for long periods of time, routine calibration as defined by manufacturer, industry, and operator standards is necessary to periodically validate measurement performance. Information provided by measurement instruments is used for process control and decision making, so a difference between an instruments output signal and the actual process condition can impact process output or facility overall performance and safety.

In all cases, the operation of a measurement instrument should be referenced, or traceable, to a universally recognized and verified measurement standard. Maintaining the reference path between a field instrument and a recognized physical standard requires careful attention to detail and uncompromising adherence to procedure.

Instrument ranging is where a certain range of simulated input conditions are applied to an instrument and verifying that the relationship between input and output stays within a specified tolerance across the entire range of input values. Calibration and ranging differ in that calibration focuses more on whether or not the instrument is sensing the input variable accurately, whereas ranging focuses more on the instruments input and output. The difference is important to note because re-ranging and re-calibration are distinct procedures.

In order to calibrate an instrument correctly, a reference point is necessary. In some cases, the reference point can be produced by a portable instrument, allowing in-place calibration of a transmitter or sensor. In other cases, precisely manufactured or engineered standards exist that can be used for bench calibration. Documentation of each operation, verifying that proper procedure was followed and calibration values recorded, should be maintained on file for inspection.

As measurement instruments age, they are more susceptible to declination in stability. Any time maintenance is performed, calibration should be a required step since the calibration parameters are sourced from pre-set calibration data which allows for all the instruments in a system to function as a process control unit.

Typical calibration timetables vary depending on specifics related to equipment and use. Generally, calibration is performed at predetermined time intervals, with notable changes in instrument performance also being a reliable indicator for when an instrument may need a tune-up. A typical type of recalibration regarding the use of analog and smart instruments is the zero and span adjustment, where the zero and span values define the instruments specific range. Accuracy at specific input value points may also be included, if deemed significant.

The management of calibration and maintenance operations for process measurement instrumentation is a significant factor in facility and process operation. It can be performed with properly trained and equipped in-house personnel, or with the engagement of subcontractors. Calibration operations can be a significant cost center, with benefits accruing from increases in efficiency gained through the use of better calibration instrumentation that reduces task time.

TECO's calibration lab is ISO/IEC 17025 Accredited. Many calibration houses can only verify calibration within the manufacturer's specifications, and it's a myth that they can fix anything that is broken.

Services include:

  • ISO/IEC 17025 Accredited Calibrations
  • NIST Traceable Calibrations
  • Live test flows on every meter repair
  • Calibration and Repair of most types of flowmeters including mass meters
  • Flowmeter calibration history files for future comparison
  • Calibration accuracy to factory specifications
  • Calibrations to multiple secondaries and across OEM product lines
  • Multiple test points available
For more information visit http://teco-inc.com or call 800-528-8997 for immediate service.

Consider Remanufactured Process Instrumentation as an Excellent Alternative to Buying New

As the world's largest remanufacturer of magnetic flow meters, TECO has the experience, trained technicians and facilities to remanufacture flanged and wafer mags to meet or exceed all OEM specifications and performance standards.

You will typically have a quotation and failure analysis in your hands by fax/email within 48 hours from the time your instruments arrive on our receiving dock. You will know your instruments are here, you will know what the price and lead time will be, and you can make a timely, informed decision. Send your business to TECO. We make it our job to help you succeed!
  • All Brands
  • NIST Traceable Certificate
  • Off-the-Shelf Meters Available
  • Obsolete Meters our Specialty
  • No Evaluation Charges
  • Magmeter Customization Services
  • All Magmeter accessories
  • New Warranty
  • Failure Analysis
  • Severe Application Meters
  • Converter/Transmitter Repairs
  • Remanufacturing is GREEN

Industrial Valve Actuators and Valve Automation

Pneumatic Valve Actuator
Pneumatic Valve Actuator (white)
Actuators are devices which supply the force and motion to open and close valves. They can be manually, pneumatically, hydraulically, or electrically operated. In common industrial usage, the term actuator generally refers to a device which employs a non-human power source and can respond to a controlling signal. Handles and wheels, technically manual actuators, are not usually referred to as actuators. They do not provide the automation component characteristic of powered units.

The primary function of a valve actuator is to set and hold the valve position in response to a process control signal. Actuator operation is related to the valve on which it is installed, not the process regulated by the valve. Thus a general purpose actuator may be used across a broad range of applications.

Electric Valve Actuator
Electric Valve Actuator (blue)
In a control loop, the controller has an input signal parameter, registered from the process, and compares it to a desired setpoint parameter. The controller adjusts its output to eliminate the difference between the process setpoint and process measured condition. The output signal then drives some control element, in this case the actuator, so that the error between setpoint and actual conditions is reduced. The output signal from the controller serves as the input signal to the actuator, resulting in a repositioning of the valve trim to increase or decrease the fluid flow through the valve.

An actuator must provide sufficient force to open and close its companion valve. The size or power of
the actuator must match the operating and torque requirements of the companion valve. After an evaluation is done for the specific application, it may be found that other things must be accommodated by the actuator, such as dynamic fluid properties of the process or the seating and unseating properties of the valve. It is important that each specific application be evaluated to develop a carefully matched valve and actuator for the process.

Hydraulic and electric actuators are readily available in multi-turn and quarter-turn configurations. Pneumatic actuators are generally one of two types applied to quarter-turn valves: scotch-yoke and rack and pinion. A third type of pneumatic actuator, the vane actuator, is also available.

For converting input power into torque, electric actuators use motors and gear boxes while pneumatic actuators use air cylinders. Depending on torque and force required by the valve, the motor horsepower, gearing, and size of pneumatic cylinder may change.

There are almost countless valve actuator variants available in the industrial marketplace. Many are tailored for very narrow application ranges, while others are more generally applied. Special designs can offer more complex operating characteristics. Ultimately, when applying actuators to any type of device, consultation with an application specialist is recommended to help establish and attain proper performance, safety and cost goals, as well as evaluation and matching of the proper actuator to the valve operation requirements. Share your fluid process control requirements with a specialist in valve automation, combining your own process knowledge and experience with their product application expertise to develop effective solutions.

ABB Rotameters

ABB rotameter
ABB rotameter
Rotameters, also known as variable area flowmeters, are designed to measure the flow of liquids or gases via a tapered tube and float system. They are accurate, reliable and simple to install and maintain. The biggest benefit is their low cost, which has made them a popular choice for many flow applications since Fischer & Porter introduced the first mass-produced glass tube flowmeter in 1937. TECO was the first firm to represent and sell the Fischer & Porter Rotameter Line, dating back to March, 1947.

The following brochure is designed to help you select the right ABB rotameter for your application. You can read it below, or download your own copy of the ABB Rotameter brochure from this link. If you have questions or are ready for a quote, simply contact TECO at 800-528-8997 or visit teco-inc.com/ABB.

Happy Fourth of July from Thompson Equipment

"We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness. — That to secure these rights, Governments are instituted among Men, deriving their just powers from the consent of the governed, — That whenever any Form of Government becomes destructive of these ends, it is the Right of the People to alter or to abolish it, and to institute new Government, laying its foundation on such principles and organizing its powers in such form, as to them shall seem most likely to effect their Safety and Happiness."

THOMAS JEFFERSON, Declaration of Independence

Steam Flow Metering and Measurement

Steam Flow Metering and Measurement
For steam, energy is primarily contained in the latent heat and, to a lesser extent, the sensible heat of the fluid. The latent heat energy is released as the steam condenses to water. Additional sensible heat energy may be released if the condensate is further lowered in temperature. In steam measuring, the energy content of the steam is a function of the steam mass, temperature and pressure. Even after the steam releases its latent energy, the hot condensate still retains considerable heat energy, which may or may not be recovered (and used) in a constructive manner. The energy manager should become familiar with the entire steam cycle, including both the steam supply and the condensate return.

When compared to other liquid flow measuring, the measuring of steam flow presents one of the most challenging measuring scenarios. Most steam flowmeters measure a velocity or volumetric flow of the steam and, unless this is done carefully, the physical properties of steam will impair the ability to measure and define a mass flow rate accurately.

Steam is a compressible fluid; therefore, a reduction in pressure results in a reduction in density. Temperature and pressure in steam lines are dynamic. Changes in the system’s dynamics, control system operation and instrument calibration can result in considerable differences between actual pressure/temperature and a meter’s design parameters. Accurate steam flow measurement generally requires the measurement of the fluid’s temperature, pressure, and flow. This information is transmitted to an electronic device or flow computer (either internal or external to the flow meter electronics) and the flow rate is corrected (or compensated) based on actual fluid conditions.

The temperatures associated with steam flow measurement are often quite high. These temperatures can affect the accuracy and longevity of measuring electronics. Some measuring technologies use close-tolerance moving parts that can be affected by moisture or impurities in the steam. Improperly designed or installed components can result in steam system leakage and impact plant safety. The erosive nature of poor-quality steam can damage steam flow sensing elements and lead to inaccuracies and/or device failure.

The challenges of measuring steam can be simplified measuring the condensed steam, or condensate. The measuring of condensate (i.e., high-temperature hot water) is an accepted practice, often less expensive and more reliable than steam measuring. Depending on the application, inherent inaccuracies in condensate measuring stem from unaccounted for system steam losses. These losses are often difficult to find and quantify and thus affect condensate measurement accuracy.

Volumetric measuring approaches used in steam measuring can be broken down into two operating designs: 
  1. Differential pressure measurement
  2. Velocity measuring technologies 

DIFFERENTIAL


For steam three differential pressure flowmeters are highlighted: orifice flow meter, annubar flow meter, and spring-loaded variable area flow meter. All differential pressure flowmeters rely on the velocity-pressure relationship of flowing fluids for operation.

Differential Pressure – Orifice Flow Meter


Historically, the orifice flow meter is one of the most commonly used flowmeters to measure steam flow. The orifice flow meter for steam functions identically to that for natural gas flow. For steam measuring, orifice flow flowmeters are commonly used to monitor boiler steam production, amounts of steam delivered to a process or tenant, or in mass balance activities for efficiency calculation or trending.

annubar flow meter
Annular flowmeter (courtesy of
Badger Meter)

Differential Pressure – Annubar Flow Meter


The annubar flow meter (a variation of the simple pitot tube) also takes advantage of the velocity-pressure relationship of flowing fluids. The device causing the change in pressure is a pipe inserted into the steam flow.

Differential Pressure – Spring-Loaded Variable Area Flow Meter


The spring-loaded variable area flow meter is a variation of the rotameter. There are alternative configurations but in general, the flow acts against a spring-mounted float or plug. The float can be shaped to give a linear relationship between differential pressure and flow rate. Another variation of the spring-loaded variable area flow meter is the direct in-line variable area flow meter, which uses a strain gage sensor on the spring rather than using a differential pressure sensor.

VELOCITY


The two main type of velocity flowmeters for steam flow, turbine and vortex shedding, both sense some flow characteristic directly proportional to the fluid’s velocity.

Turbine Flow Meter


A multi-blade impellor-like device is located in, and horizontal to, the fluid stream in a turbine flow meter. As the fluid passes through the turbine blades, the impellor rotates at a speed related to the fluid’s velocity. Blade speed can be sensed by a number of techniques including magnetic pick-up, mechanical gears, and photocell. The pulses generated as a result of blade rotation are directly proportional to fluid velocity, and hence flow rate.

Velocity – Vortex-Shedding Flow Meter
vortex-shedding flow meter
Vortex flowmeter (courtesy of Badger Meter)


A vortex-shedding flow meter senses flow disturbances around a stationary body (called a bluff body) positioned in the middle of the fluid stream. As fluid flows around the bluff body, eddies or vortices are created downstream; the frequencies of these vortices are directly proportional to the fluid velocity.


For more information on any flow measurement requirement, visit Thompson Equipment (TECO) at http://www.teco-inc.com or call 800-528-8997 for immediate service,

Water Flow Metering and Measurement

water flow measurement devices
Water flow measurement device comparison (click for larger view)
Water is commonly measured and sold in volumetric measurements, which allows for lower-cost metering options. The specific measurement technology chosen will depend on a number of factors including, but not limited to, current design, budget, accuracy requirements, resolution, minimum flow rate, potable versus non-potable (or at least filtered versus non-filtered water), range of flow rates, and maximum flow rate.

Volumetric water measurement can be broken down into three general operating designs:
  • Positive displacement
  • Differential pressure
  • Velocity

Positive Displacement – Nutating-Disk Flow Meter

Nutating-disk flow meters are the most common meter technology used by water utilities to measure potable-water consumption for service connections up to 3-inch. The nutating-disk flow meter consists of a disk mounted on a spherically shaped head and housed in a measuring chamber. As the fluid flows through the meter passing on either side of the disk, it imparts a rocking or nutating motion to the disk. This motion is then transferred to a shaft mounted perpendicular to the disk. It is this shaft that traces out a circular motion – transferring this action to a register that records flow.

There are a variety of differential pressure devices useful for water metering; two of the more common devices include orifice flow meters and venturi flow meters.

Differential Pressure – Orifice Flow Meter

The orifice element is typically a thin, circular metal disk held between two flanges in the fluid stream. The center of the disk is formed with a specific-size and shape hole, depending on the expected fluid flow parameters (e.g., pressure and flow range). As the fluid flows through the orifice, the restriction creates a pressure differential upstream and downstream of the orifice proportional to the fluid flow rate. This differential pressure is measured and a flow rate calculated based on the differential pressure and fluid properties.

Differential Pressure – Venturi Flow Meter

The venturi flow meter takes advantage of the velocity-pressure relationship when a section of pipe gently converges to a small-diameter area (called a throat) before diverging back to the full pipe diameter. The benefit of the venturi flow meter over the orifice flow meter lies in the reduced pressure loss experienced by the fluid.

The velocity measurement technologies described in this section include the turbine flow meter, vortex-shedding flow meter, and ultrasonic flow meters.

Velocity – Turbine Flow Meter

A multi-blade impellor-like device is located in, and horizontal to, the fluid stream in a turbine flow meter. As the fluid passes through the turbine blades, the impellor rotates at a speed related to the fluid’s velocity. Blade speed can be sensed by a number of techniques including magnetic pick-up, mechanical gears, and photocell. The pulses generated as a result of blade rotation are directly proportional to fluid velocity, and hence flow rate.

Velocity – Vortex-Shedding Flow Meter

A vortex-shedding flow meter senses flow disturbances around a stationary body (called a bluff body) positioned in the middle of the fluid stream. As fluid flows around the bluff body, eddies or vortices are created downstream; the frequencies of these vortices are directly proportional to the fluid velocity.

Velocity – Ultrasonic Flow Meters

There are two different types of ultrasonic flow meters, transit-time and Doppler-effect. The two technologies use ultrasonic signals very differently to determine fluid flow and are best applied to different fluid applications. Transit-time ultrasonic flow meters require the use of two signal transducers. Each transducer includes both a transmitter and a receiver function. As fluid moves through the system, the first transducer sends a signal and the second receives it. The process is then reversed. Upstream and downstream time measurements are compared. With flow, sound will travel faster in the direction of flow and slower against the flow. Transit-time flow meters are designed for use with clean fluids, such as water.

Doppler-effect ultrasonic flow meters use a single transducer. The transducer has both a transmitter and receiver. The high-frequency signal is sent into the fluid. Doppler-effect flow meters use the principal that sound waves will be returned to a transmitter at an altered frequency if reflectors in the liquid are in motion. This frequency shift is in direct proportion to the velocity of the liquid. The echoed sound is precisely measured by the instrument to calculate the fluid flow rate.

Because the ultrasonic signal must pass through the fluid to a receiving transducer, the fluid must not contain a significant concentration of bubbles or solids. Otherwise the high frequency sound will be attenuated and too weak to traverse the distance to the receiver. Doppler-effect ultrasonic flow meters require that the liquid contain impurities, such as gas bubbles or solids, for the Doppler-effect measurement to work. One of the most attractive aspects of ultrasonic flow meters is they are non-intrusive to the fluid flow. An ultrasonic flow meter can be externally mounted to the pipe and can be used for both temporary and permanent metering.

For more information on any flow application, visit http://www.teco-inc.com or call (504) 833-6381.


Natural Gas Flow Metering and Measurement


Natural gas is a hydrocarbon gas mixture consisting primarily methane, but includes a host of other chemical components. Accurate natural gas flow measurement usually requires the measurement of the fluid’s temperature and pressure in addition to flow. Additional constraints on natural gas measurement may include the physical space available or possibly configuration and weight of the metering system. Some of the fluid metering technologies require specific lengths of pipe, both upstream and downstream of the meter for proper function.

Before any technology decisions are made, discussions with equipment vendors and/or design engineers are recommended to ensure proper technology selection and installation design.

Depending on the application, flow rate, installation access, and desired accuracy, there are a number of technology options for natural gas metering. In general, measurement of natural gas volumetric flow rate is represented in standard cubic feet per hour (scfh) or per minute (scfm). The actual mass of gas flowing past a point of measurement changes with its temperature and pressure. Density changes resulting from temperature and pressure differences can result in differences between the energy content of similar volumes of the gas. To equalize the effect of density variations when metering gas, conditions are referenced against standard temperature and pressure conditions, hence standard cubic feet (scf) instead of actual cubic feet (acf). Gas flowmeters must compensate for density differences between standard conditions and actual conditions to accurately define standard flow rates.

The most common volumetric gas metering devices fall into one of the following categories:
  • Positive displacement
  • Differential pressure
  • Velocity 
In most applications, gas flowmeters are installed downstream of pressure regulation devices and the meters are then calibrated to that pressure. Natural gas meters may include options for temperature and pressure compensation.


POSITIVE DISPLACEMENT


A positive displacement meter functions by the fluid physically displacing the measuring mechanism and this displacement becomes the metered value. Of relevancy to natural gas measurement, the two predominant technologies are the diaphragm meter (most common) and the rotary meter. In each case, the volume of gas for measurement physically impinges on a measuring element (flexible diaphragm or rotary blower) to increment a recording dial or other output. The primary advantage of positive displacement flow meters is there are no straight-run piping requirements to establish a flow pattern that can be accurately metered. The primary disadvantage of positive displacement meters is higher pressure drops experienced across the meter at peak flow rates.


DIFFERENTIAL PRESSURE


There are multiple types of differential pressure meters: orifice flow meter, venture flow meter, and annubar flow meter. All differential pressure meters rely on the velocity-pressure relationship of flowing fluids for operation.

Orifice Flow Meter 
The orifice element is typically a thin, circular metal disk held between two flanges in the fluid stream. The center of the disk is formed with a specific-size and shape hole, depending on the expected fluid flow parameters (e.g., pressure and flow range). As the fluid flows through the orifice, the restriction creates a pressure differential upstream and downstream of the orifice proportional to the fluid flow rate. This differential pressure is measured and a flow rate calculated based on the differential pressure and fluid properties.

Venturi Flow Meter
The venturi flow meter takes advantage of the velocity- pressure relationship when a section of pipe gently converges to a small-diameter area (called a throat) before diverging back to the full pipe diameter. The benefit of the venturi flow meter over the orifice flow meter lies in the reduced pressure loss experienced by the fluid.

Annubar Flow Meter
The annubar flow meter (a variation of the simple pitot tube) also takes advantage of the velocity-pressure relationship of flowing fluids. The device causing the change in pressure is a pipe inserted into the natural gas flow.


VELOCITY


There are multiple types of velocity meters: turbine flow meter, vortex-shedding flow meter, and fluid oscillation flow meter. Velocity meters determine fluid flow by measuring a representation of the flow directly. Because the fluid’s velocity is measured (i.e., not the square-root relationship to determine velocity as with differential pressure meters), velocity meters can have better accuracy and usually have better turndown ratios than other meter types.

Turbine Flow Meter
A multi-blade impellor-like device is located in, and horizontal to, the fluid stream in a turbine flow meter. As the fluid passes through the turbine blades, the impellor rotates at a speed related to the fluid’s velocity. Blade speed can be sensed by a number of techniques including magnetic pick-up, mechanical gears, and photocell. The pulses generated as a result of blade rotation are directly proportional to fluid velocity, and hence flow rate.

Vortex-Shedding Flow Meter
A vortex-shedding flow meter senses flow disturbances around a stationary body (called a bluff body) positioned in the middle of the fluid stream. As fluid flows around the bluff body, eddies or vortices are created downstream; the frequencies of these vortices are directly proportional to the fluid velocity.

Fluid Oscillation Flow Meter
A fluid oscillation flow meter uses sensor technology to detect gas oscillations, which corresponds to the flow rate through the meters internal throat design.

For more information on any flow measurement requirement, visit Thompson Equipment (TECO) at http://www.teco-inc.com or call 800-528-8997 for immediate service,

Flow Media Identification in Process Piping

Fluid process control operations use pipes to transport materials over distances. Other processing facilities may also employ piping as a conduit to move a variety of other materials. Factory piping networks move liquids and gasses from process point to process point. An accurate indication of the nature and type of substance or material within a pipe, direction of flow, or other pertinent information, contributes to maintaining a safe and effective operation. Pipe marking and color coding should follow recognized applicable standards that are well known to plant operators. 

With pipe marking following a standardized system, employees and contractors on site, and with knowledge of the applicable marking system, are able to easily understand the different colors and their relation to the facility functions. However, some pipes, such as ammonia refrigeration pipes, have their own, independent standards which can be integrated alongside other identifications. Similarly, pipes used in marine environments bear their own standards, along with specific color combinations and banding. Those two sets of standards comply with the hallmarks of general pipe labeling, coloring and identification, including color coding, simple identification of the pipes content, and the inclusion of an accompanying symbol indicating the direction of the flow. For example, a green pipe with white lettering generally means the adjoining pipe contains potable water, potentially for cooling, boiler feeding, or sinks. All combustible fluids are paired with brown labels and white lettering. In addition to the number of predetermined combinations, user defined pipe color combinations are possible so that businesses may plot certain pipes which do not immediately fit within the preset. These can present a challenge, though, due to the fact that user defined color options will require additional instruction to employees and contractors because of their uniqueness to specific businesses. 

The labels used to identify pipes have their own specifications for size and lettering dimensions. Size requirements for the labels allow for companies to create custom labels while still adhering to universal conditions. The size of the pipe markings is related to the pipe diameter, and meant to ensure visibility. An easy way for businesses to translate pipe labels for their employees is to develop and display color code charts. An employee not immediately familiar with the realm of pipe labeling can quickly reference an accurate, accessible chart before taking any action. The maximization of facility safety relies on ensuring that the pipe color labels are visible, unobstructed, and well-lit. Labels placed every 25-50', especially on a pipe that changes direction, near an access point, or near an end point, place information at important junctures on the pipeline. Clearly understanding both the substance a pipe is carrying and, additionally, how individual pipes constitute the facility network is a key way to mitigate potential process hazards.

Blog post courtesy of Thompson Equipment.

Rack and Pinion Pneumatic Valve Actuators

Rack and pinion actuator
Rack and pinion actuator
(courtesy of Jamesbury)
There are three primary categories of valve actuators commonly used valve automation:
  • Pneumatic
  • Hydraulic
  • Electric
Pneumatic actuators can be further categorized as:
  • Scotch yoke design
  • Vane design
  • Rack and pinion actuators (the subject of this post).
Animation of how rack
and pinion gears convert linear
motion to rotational motion.
Rack and pinion actuators provide a rotational movement designed to open and close quarter-turn valves such as ball, butterfly, or plug valves and also for operating 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”.

Pneumatic actuators use pistons that are attached to the rack. As air or spring power is applied the to pistons, the rack is “pushed” inward or “pulled” outward. This linear movement is transferred to the rotary pinion gear (in both directions) providing bi-directional rotation.


Rack and pinion gear configuration
Actuator rack & pinion gear configuration
Rack and pinion actuators pistons can be pressurized with air, gas, or oil to provide the linear the movement that spins the pinion gear. To rotate the pinion gear in the opposite direction, the air, gas, or oil must be redirected to the other sides of the piston, or use coil springs as the energy source for rotation. Rack and pinion actuators using springs are referred to as "spring-return actuators". Actuators that rely on opposite side pressurization of the rack are referred to as "direct acting".
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.

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.

Pneumatic pneumatic rack and pinion actuators are compact and save space. They are reliable, durable and provide a good life cycle. There are many brands of rack and pinion actuators on the market, all with subtle differences in piston seals, shaft seals, spring design and body designs.

For more information on any pneumatic or electric valve automation project, visit this link or call TECO at 800-528-8997.

Measuring Flow Using Differential Pressure

Bernoulli's principle
There are several types of flow instruments that rely on the Bernoulli's principle (an increase in the speed of a fluid occurs simultaneously with a decrease in pressure), that measure the differential pressure across the high pressure side and low pressure side of a constriction.

Many industrial processes adapt this principle and measure the differential pressure across an orifice plate or a Venturi tube to measure and control flow.

An orifice plate is a plate with a hole through it. When placed in the pipe, it constricts the flow and provides a pressure differential across the constriction which can be correlated to the flow rate.

A Venturi tube constricts the flow in the same fashion, but instead a plate with a hole, it uses a pipe or tube with a reduced inner diameter to create the flow differential.

This video provides an excellent basic understanding of how this is accomplished. For more information on any type of industrial flow measuring device, visit the TECO website o call 800-528-8997.

NIST Certification of Flow Instrument Calibration and ISO/IEC 17025 Accreditation

The Thompson Equipment Co., Inc., (TECO) facility is used for performing flow calibration for magnetic flow meters as well as other primary liquid flow measuring devices. It is equipped with both mass and volumetric transfer standards.

The output of a customer owned meter is correlated with the output of a standard volumetric meter over a range of its flow capabilities. Each six months, each volumetric standard meter is calibrated against a mass standard. Each year the mass standards are calibrated against the Louisiana Department of Agriculture Standards Laboratory. 

Also on a periodic basis, standards owned by the LA Dept. of Agriculture are calibrated against the National Institute of Standards and Technology (NIST) Each standard device carries with it the appropriate certificate identifying when its last calibration was performed, and by ID number, which standard device it was calibrated against. 

The NIST Traceable Calibration Certificate from TECO documents this trail of calibration so that the calibration of any flow meter can be confirmed all the way back to the NIST Laboratories as is often required by regulatory agencies, ISO-9000 procedures, etc. This provides the user with a high level of confidence in the readings from his instrument.

ISO/IEC 17025 Accredited


TECO's calibration lab is also ISO/IEC 17025 Accredited, meaning it is in accordance with the recognized International Standard ISO/IEC 17025:2005 General requirements for the competence of testing and calibration laboratories. The TECO laboratory also meets any additional program requirements in the field of calibration. This accreditation demonstrates technical competence for a defined scope and the operation of a laboratory quality management system.

Unlike many calibration houses can only verify calibration within the manufacturer's specifications, TECO can provide a wide range of fully accredited flow calibration services to meet virtually any need.

For more information, contact TECO at 800-528-8997 or visit http://teco-inc.com.

Introduction to Transmitters used in Process Control

Flow transmitter
Flow transmitter (ModMag)
Transmitters are process control field devices. They receive input from a connected process sensor, then convert the sensor signal to an output signal using a transmission protocol. The output signal is passed to a monitoring, control, or decision device for use in documenting, regulating, or monitoring a process or operation.

In general, transmitters accomplish three steps, including converting the initial signal twice. The first step is the initial conversion which alters the input signal to make it linear. After an amplification of the converted signal, the second conversion changes the signal into either a standard electrical or pneumatic output signal that can be utilized by receiving instruments and devices. The third and final step is the actual output of the electrical or pneumatic signal to utilization equipment - controllers, PLC, recorder, etc.

Transmitters are available for almost every measured parameter in process control, and are often referred to according to the process condition which they measure. Some examples.

  • Pressure transmitters
  • Temperature transmitters
  • Flow transmitters
  • Level transmitters
  • Vibration transmitters
  • Current, voltage & power transmitters
  • PH, conductivity, dissolved gas transmitters, etc. 
  • Consistency

Consistency Transmitter
Consistency Transmitter(TECO)
Output signals from transmitters, when electrical, often are either voltage (1-5 or 2-10 volts DC) or current (4-20 mA). Power requirements can vary among products, but are often 110/220 VAC or 24 VDC.  Low power consumption by electrical transmitters can permit some units to be "loop powered", operating from the voltage applied to the output current loop. These devices are also called "two-wire transmitters" because only two conductors are connected to the unit. Unlike the two wire system which only needs two wires to power the transmitter and carry the analog signal output, the four-wire system requires four separate conductors, with one pair serving as the power supply to the unit and a separate pair providing the output signal path. Pneumatic transmitters, while still in use, are continuously being supplanted by electrical units that provide adequate levels of safety and functionality in environments previously only served by pneumatic units.

Pressure Transmitter
Pressure
Transmitter
(ifm)
Many transmitters are provided with higher order functions in addition to merely converting an input signal to an output signal. On board displays, keypads, Bluetooth connectivity, and a host of industry standard communication protocols can also be had as an integral part of many process transmitters. Other functions that provide alarm or safety action are more frequently part of the transmitter package, as well.

Wireless transmitters are also available, with some operating from battery power and negating the need for any wired connection at all. Process transmitters have evolved from simple signal conversion devices to higher functioning, efficient, easy to apply and maintain instruments utilized for providing input to process control systems.

To lean more about instrumentation and control, visit http://www.teco-inc.com or call Thompson Equipment at 800-528-8997.

ifm Industrial Sensors and Control Products

ifm Temperature sensor
ifm Temperature Sensor
ifm is one of the world’s largest manufacturers of industrial sensors and controls products, producing over 9 million sensors annually. Products include position sensors, sensors for motion control, vision sensors, safety technology, process sensors, and sensors for industrial networks.

Below is ifm's complete catalog to familiarize you with their products.

For assistance with ifm products, visit TECO's website, or call 800-528-8997 for immediate service.