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 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

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 


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.


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 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 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.


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.


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.


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 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

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
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 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.

Turbine Flowmeters

Turbine flowmeters use a free-spinning turbine wheel to measure fluid velocity, much like a miniature windmill installed in the flow stream. The fundamental design goal of a turbine flowmeter is to make the turbine element as free-spinning as possible, so no torque will be required to sustain the turbine’s rotation. If this goal is achieved, the turbine blades will achieve a rotating (tip) velocity directly proportional to the linear velocity of the fluid, whether that fluid is a gas or a liquid:
Diagram of turbine flowmeter

The mathematical relationship between fluid velocity and turbine tip velocity – assuming frictionless conditions – is a ratio defined by the tangent of the turbine blade angle:

For a 45o blade angle, the relationship is 1:1, with tip velocity equaling fluid velocity. Smaller blade angles (each blade closer to parallel with the fluid velocity vector) result in the tip velocity being a fractional proportion of fluid velocity.

Turbine tip velocity is quite easy to sense using a magnetic sensor, generating a voltage pulse each time one of the ferromagnetic turbine blades passes by. Traditionally, this sensor is nothing more than a coil of wire in proximity to a stationary magnet, called a pickup coil or pickoff coil because it “picks” (senses) the passing of the turbine blades. Magnetic flux through the coil’s center increases and decreases as the passing of the steel turbine blades presents a varying reluctance (“resistance” to magnetic flux), causing voltage pulses equal in frequency to the number of blades passing by each second. It is the frequency of this signal that represents fluid velocity, and therefore volumetric flow rate.

A cut-away demonstration model of a turbine flowmeter is shown in the following photograph. The blade sensor may be seen protruding from the top of the flowtube, just above the turbine wheel:

Turbine flowmeter
Turbine flowmeter cutaway
Note the sets of “flow conditioner” vanes immediately before and after the turbine wheel in the photograph. As one might expect, turbine flowmeters are very sensitive to swirl in the process fluid flowstream. In order to achieve high accuracy, the flow profile must not be swirling in the vicinity of the turbine, lest the turbine wheel spin faster or slower than it should to represent the velocity of a straight-flowing fluid. A minimum straight-pipe length of 20 pipe diameters upstream and 5 pipe diameters downstream is typical for turbine flowmeters in order to dissipate swirl from piping disturbances.

Mechanical gears and rotating cables have also been historically used to link a turbine flowmeter’s turbine wheel to indicators. These designs suffer from greater friction than electronic (“pickup coil”) designs, potentially resulting in more measurement error (less flow indicated than there actually is, because the turbine wheel is slowed by friction). One advantage of mechanical turbine flowmeters, though, is the ability to maintain a running total of gas usage by turning a simple odometer-style totalizer. This design is often used when the purpose of the flowmeter is to track total fuel gas consumption (e.g. natural gas used by a commercial or industrial facility) for billing.

For more information on turbine flowmeters, contact Thompson Equipment Company (TECO) by visiting their website at or call 800-528-8997.

Reprinted from "Lessons In Industrial Instrumentation" by Tony R. Kuphaldt under the Creative Commons Attribution 4.0 International Public License.

Paper Production: Measuring Freeness Produces More Salable Product

Measuring Freeness improves quality
Measuring Freeness improves quality in paper production.
Better quality and more salable paper is the outcome of accurately measuring freeness at the beginning of the manufacturing process. Controlling freeness makes production lines more efficient and capable of producing better quality paper at a lower cost per ton.

According to the North Carolina State Mini-Encyclopedia of Papermaking Wet-End Chemistry, freeness is defined as “a measure of how quickly water is able to drain from a fiber furnish sample. In many cases there is a correlation between freeness values and either (a) a target level of refining of pulp, or (b) the ease of drainage of white water from the wet web, especially in the early sections of a Fourdrinier former. Standard tests of freeness are based on gravity dewatering through a screen. The devices are designed so that an operator can judge the speed of dewatering by observing the volume of liquid collected in a graduated cylinder. Freeness tends to be decreased by refining and by increases in the level of fines in the furnish. Freeness can be increased by use of drainage aids, removal of fines, or enzymatic treatments to convert mucilaginous materials into sugars."

TECO (Thompson Equipment Company) has been serving the pulp and paper industry for over 60 years, and has helped hundreds of clients with their unique Drainac® Drainage Rate Indication System. The Drainac® is an on-line instrument that continually measures the drainage rate of pulp and provides a proportional 4-20 mA DC signal. The unit consists of two major sub-assemblies; a detector and a detector control cabinet. It has earned a reputation as the fastest, lowest cost, and most pain-free device of its kind for measuring freeness.

Basic Applications

Closed Loop Refiner Controls – On-line freeness measurement is commonly used to control the final freeness target (setpoint) for the refiners by cascading the freeness measurement output directly to the horsepower tons / day controller.

Basic On-line Freeness Measurement – Basic on-line freeness measurement is used by production managers and paper machine operators as a “speedometer” of fiber quality enabling them to make real- time decisions that effect final production quality and paper machine run-ability.

Stock Blending – Used for monitoring the fiber characteristics of individual furnish streams so that optimal stock blending can be accomplished on a real-time basis. In this manner, the lower cost furnish stream can be maximized without sacrificing final product quality.

Please watch the video below for a better understanding of why its important to measure freeness for improved paper quality. For more information on freeness measurement, visit or call TECO at 800-528-8997.

Introduction to Industrial Flowmeters

Magnetic flowmeter
(courtesy of Badger Meter)
Flowmeters measure the rate or quantity of moving fluids, in most cases liquid or gas, in an open channel or closed conduit. There are two basic flow measuring systems: those which produce volumetric flow measurements and those delivering a weight or mass based measurement. These two systems, required in many industries such as power, chemical, and water, can be integrated into existing or new installations. For successful integration, the flow measurement systems can be installed in one of several methods, depending upon the technology employed by the instrument. For inline installation, fittings that create upstream and downstream connections that allow for flowmeter installation as an integral part of the piping system. Another configuration, direct insertion, will have a probe or assembly that extends into the piping cross section. There are also non-contact instruments that clamp on the exterior surface of the piping add gather measurements through the pipe wall without any contact with the flowing media.
Turbine flowmeter
Turbine flowmeter
(courtesy of Badger Meter)

Because they are needed for a variety of uses and industries, there are multiple types of flowmeters classified generally into four main groups: mechanical, inferential, electrical, and other.

Quantity meters, more commonly known as positive displacement meters, mass flowmeters, and fixed restriction variable head type flowmeters all fall beneath the mechanical category. Fixed restriction variable head type flowmeters use different sensors and tubes, such as orifice plates, flow nozzles, and venturi and pitot tubes.
Variable area flowmeter
(courtesy of ABB)

Inferential flowmeters include turbine and target flowmeters, as well as variable area flowmeters also known as rotameters.

Laser doppler anemometers, ultrasonic flowmeters, and electromagnetic flowmeters are all electrical-type flowmeters.

TECO Flowmeter and Process Instrument Remanufacturing

As the world’s largest remanufacturer of flowmeters and process instruments, TECO has the experience, trained technicians, and facilities to remanufacture your equipment to meet or exceed all OEM specifications and performance standards.

TECO also has a "No Hassle Guarantee". Just send in your item, no form needed, no RMA required, and they'll respond in 48 hours. | 800-528-8997

An Introduction to Industrial Valve Actuators

Industrial Valve Actuators
Industrial Valves and Valve Actuators
Valves are essential to industries which constitute the backbone of the modern world. The prevalence of valves in engineering, mechanics, and science demands that each individual valve performs to a certain standard. Just as the valve itself is a key component of a larger system, the valve actuator is as important to the valve as the valve is to the industry in which it functions. Actuators are powered mechanisms that position valves between open and closed states; the actuators are controllable either by manual control or as part of an automated control loop, where the actuator responds to a remote control signal. Depending on the valve and actuator combination, valves of different types can be closed, fully open, or somewhere in-between. Current actuation technology allows for remote indication of valve position, as well as other diagnostic and operational information. Regardless of its source of power, be it electric, hydraulic, pneumatic, or another, all actuators produce either linear or rotary motion under the command of a control source.

Thanks to actuators, multiple valves can be controlled in a process system in a coordinated fashion; imagine if, in a large industrial environment, engineers had to physically adjust every valve via a hand wheel or lever! While that manual arrangement may create jobs, it is, unfortunately, completely impractical from a logistical and economic perspective. Actuators enable automation to be applied to valve operation.

Pneumatic actuators utilize air pressure as the motive force which changes the position of a valve. Pressurized-liquid reliant devices are known as hydraulic actuators. Electric actuators, either motor driven or solenoid operated, rely on electric power to drive the valve trim into position. With controllers constantly monitoring a process, evaluating inputs, changes in valve position can be remotely controlled to provide the needed response to maintain the desired process condition.

Manual operation and regulation of valves is becoming less prevalent as automation continues to gain traction throughout every industry. Valve actuators serve as the interface between the control intelligence and the physical movement of the valve. The timeliness and automation advantages of the valve actuators also serve as an immense help in risk mitigation, where, as long as the system is functioning correctly, critical calamities in either environmental conditions or to a facility can be pre-empted and quickly prevented. Generally speaking, manual actuators rely on hand operation of levers, gears, or wheels, but valves which are frequently changed (or which exist in remote areas) benefit from an automatic actuator with an external power source for a myriad of practical reasons, most pressingly being located in an area mostly impractical for manual operation or complicated by hazardous conditions.

Thanks to their versatility and stratified uses, actuators serve as industrial keystones to, arguably, one of the most important control elements of industries around the world. Just as industries are the backbones of societies, valves are key building blocks to industrial processes, with actuators as an invaluable device ensuring both safe and precise operation.

Thompson Equipment (TECO) specifies, designs, and fabricates complete valve automation solutions for a wide variety of industries. Contact TECO for your next valve automation requirement.

Basics and Practice of Applying ABB Rotameters (Variable Area Flowmeters)

ABB Variable Area flowmeters
Diagram of rotameter
(courtesy of ABB)
For decades variable Area flowmeters have become established in industrial measure- ment technology with an economical, mature measurement principle. The large variety of instrument designs, their repeatability and independence from supply power require- ments for local indication provide a suitable solution in almost every flow metering ap- plication for liquids, gases and steam.

The ABB-Program includes, a line of metal meter tube flowmeters particularly suited for high pressure and temperature applications, for aggressive and opaque fluids and for steam metering. Also offered is a line of glass meter tube flowmeters (the solution for extremely low pressure conditions) including float designs for viscous fluids or high flowrates in the smaller sizes. The purge flowmeters in both lines are available with a differential pressure regulator to maintain a constant flowrate even when there are pressure variations. The smallest flow ranges required in laboratory applications and high flowrates in industrial applications can be satisfied with ABB instruments.

This new “Handbook for Variable Area Flowmeters“ is a practical guide for the user with selection criteria for real applications (see Check List/Parameter Questionnaire), correction factors, Accuracy Classes, corrosion resistance tables and much more. A separate flyer with actual pictures demonstrate the application versatility.

Answers are provided to frequently asked questions about this measurement principle (see Page 20) and we have incorporated a preferential quick ship program for the most popular instrument versions.

We hope that this Handbook provides you with a practical selection guide; naturally our sales team is always ready to provide you with any personal assistance you may require.

For more information on any ABB variable area flow meter (rotameter), visit TECO at or call (504) 833-6381.

Bubble Tube Purge for Level Measurement

ABB Rotameter
ABB Rotameter
Description of Application

One of the most widely used methods of monitoring/controlling liquid level in a tank is the use of Bubble Tubes with Pressure or Differential Pressure Transmitters. A small, but uninterrupted flow of air or inert gas is forced down through a dip tube which extends to near the bottom of the tank. The back pressure of the introduced gas is a function of the liquid level or head in the tank.

Where Used
  • Chemical Companies
  • Food & Beverage Companies
How Installed

Bubble Tube Purge for Level Measurement
Bubble Tube Purge for Level Measurement (click for larger view)

Rotameter Solution

The use of a Purge type Rotameter is the least expensive and most convenient way to set and monitor the flow of air or inert gas into the Bubble Tube.

Method Of Operation

A small, but uninterrupted flow of air (or inert gas such as nitrogen) is easily set and monitored by the use of a Purge Type Rotameter. The flow rate must be low to insure no increase in head back pressure due to pressure drop through the purge piping and dip tube. Conversely the flow cannot be interrupted or the back pressure may decrease below that of the head giving an incorrect level reading and possibly allowing the process liquid to reflux back to the purgemeter and ∆/P Transmitter. Note that controlling the exact flow rate is not critical. The flow rate must be low and uninterrupted. The purge supply gas pressure must exceed the maximum line pressure by about 10psi.

For more information, contact Thompson Equipment at 800-528-8997 or visit

Valve Automation Professionals Will Save You Time and Money on Your Next Industrial Valve Project

Teco Valve Automation Expert
Local Distributors and Reps provide great value when
working on automated valve projects.
Local distributors and representatives who sell industrial valves, actuators and controls also provide services and equipment that will save you time, money, and help you achieve a better outcome for the entire project.

Projects requiring engineered valve systems are best completed and accomplished through the proper selection and application of the valves, actuators, positioners, limit switches and other associated components. A great resource exists, ready to provide a high level of technical knowledge and assistance, that can be easily tapped to help you with your project - the valve automation sales professional.

Consider a few of the things the valve automation professional brings to your project:

Product Knowledge: Valve automation professionals are current on product offerings, proper application technique, and product capabilities. They also posses  information on future product obsolescence and upcoming new designs. This type of information is not generally accessible to the public via the Internet.

Experience: As a project engineer, you may be treading on new ground regarding some aspects of your current valve system design assignment. There can be real benefit in connecting to an experienced and highly knowledgable source, with past exposure to your current challenges.

Access: Through a valve automation professional, you may be able to establish a connection to “behind the scenes” manufacturer contacts with essential information not publicly available. The rep knows people at the factories, a well as at other valve related companies, who can provide quick and accurate answers to your valve automation related questions.

Of course, any valve actuation or automation solution proposed are likely to be based upon the products sold by the representative. That is where considering and evaluating the benefits of any solution becomes part of achieving the best project outcome.

Develop a professional, mutually beneficial relationship with a local valve automation professional to make your design job go after, more efficiently, and more cost effective. Their success is tied to your success, and they are eager to help you.

Basics of Process Piping: Piping & Instrument Diagrams

P&ID's (piping & instrumentation diagrams), or Process and Control Flow Diagrams, are schematic representations of a process control system and used to illustrate the piping system, process flow, installed equipment, and process instrumentation and functional relationships therein.

P&ID’s can be very detailed and are generally the primary source from where instrument and equipment lists are generated and are very handy reference for maintenance and upgrades. P&ID’s also play an important early role in safety planning through a better understanding of the operability and relationships of all components in the system.

Intended to provide a “picture” of all of piping including the physical branches, valves, equipment, instrumentation and interlocks. The P&ID uses a set of standard symbols representing each component of the system such as instruments, piping, motors, pumps, etc.

For more information on any process instrument question or requirement, feel free to contact the application engineers at Thompson Equipment. For immediate service call 800-528-8997

Custom Magmeters for the Most Abrasive and Erosive Slurry Application

custom magmeter
Custom magnetic flowmeter with
engineered ceramic
brick liner.
When you have suspended solids, such as cement, coal, or fly ash, mixed with a liquid (such as water), a mud-like substance referred to as a “slurry” is formed. Measuring flow of slurries is often times challenging because of their abrasive nature and the wear and tear flowmeters experience. Add to the challenge a carrier fluid that is highly caustic or acidic, and the flow measurement task becomes geometrically more difficult.

In certain industries this situation is very common. Slurry processing applications in mining, dredging, pulp & paper, fracking, oil and gas exploration (drilling slurries - not the old or gas), and wastewater treatment all have areas that present a variety of highly erosive and corrosive slurries. In these situations off-the-shelf magnetic flowmeters won’t last, so consideration must be given to custom flowmeters built specifically to withstand the application’s unique requirements. A complete understanding of the composition of the chemical and particulate nature of the slurry and the flow conditions is critical.
Dredging is an example of challenging slurry flow measurement. 

Customized magnetic flowmeters with very high erosion and abrasion resistance incorporate specialized materials and unique features that increase the performance and service life for that application. These flowmeters are highly engineered and the selection of a manufacturer with the experience, production capability, and quality control is imperative.

Here is a partial list of specialized features available from custom flowmeter manufacturers:

Specialty liners:

  • Magnesia stabilized Zirconia ceramic
  • Aluminum Oxide ceramic
  • Polyurethane rubber
  • Neoprene rubber
  • Linatex
  • Teflon (PTFE)
  • Rotationally molded Tefzel (ETFE)
  • PFA

Specialty electrodes: 

  • Stainless Steel
  • Hastalloy B/C
  • Titanium
  • Platinum/Iridium
  • Tungston Carbide

Exotic Tube Construction:

  • 100% Titanium
  • Marine Epoxy paints
  • Powder coating

In summary, when faced with measuring the flow of a highly erosive and abrasive slurry, it’s best to call upon a company with the expertise and production capabilities to match the flowmeter design exactly with the application requirements. Take the time to do this up front, and resist the temptation to “wing-it” with and install a generically designed flowmeter. Doing so will pay off in service life and overall cost in the long run.

The Operating Principles of a Magnetic Flowmeter

Below is a video, courtesy of Badger Meter, illustrating the operating principles of magnetic flowmeters (also known as magmeters).

A magnetic field is applied to the flow tube, resulting in an EMF proportional to the flow velocity passing perpendicular to the magnetic flux lines. The physical principle at work is Faraday's law of electromagnetic induction.

Magnetic flow meter requires a conductive fluid, and electrically insulated internal pipe surfaces to operate.

  • Low maintenance cost
  • No moving parts
  • Good for slurry
  • Good for corrosive fluids
  • Very linear
  • Minimal flow restriction

  • Requires electrically conductive fluids
For more information on magmeters, visit TECO at of call 800-528-8997.