Showing posts with label process measurement. Show all posts
Showing posts with label process measurement. Show all posts

Monday, January 29, 2018

Understanding Hydrostatic Pressure in Process Control

Hydrostatic pressure transmitter
Transmitter used to measure
hydrostatic pressure. (Yokogawa)
The pressure exerted by a fluid material in a vessel is directly proportional to its height multiplied by its density.

Hydrostatic pressure, or head pressure, is the force produced by a column of material. As the height of the material changes, there is proportional change in pressure. To calculate hydrostatic pressure, the density of the material is multiplied by the height of the column. The level of fluid in a column can be determined by dividing the pressure value by the density of the material.


To find pressure in a column of water, a gauge placed at the bottom of the vessel. With the water having a density of 0.0361 pounds per cubic inch, the level of the fluid is calculated by dividing the head pressure by the density of the fluid.

An example to determine the level measurement of a column of water that is 2 feet tall in diameter of 0.5 feet is solved by the following steps. The first step is measuring the weight of the vessel. Next measure the weight of the vessel with fluid. The weight of the fluid is determined by subtracting the weight of the vessel from the weight of the vessel with fluid. The volume of the fluid is then derived by dividing the fluid weight by the density of the fluid. The level of the fluid is finally calculated by dividing the volume of the fluid by the surface area.

Hydrostatic pressure can only be calculated from an open container. Within a closed vessel, or pressurized vessel, the vapor space above the column of material adds pressure, and results in inaccurate calculated values. The vessel pressure can be compensated for by using a differential pressure transmitter. This device has a high pressure side input and a low pressure side input. The high-pressure input is connected to the bottom of the tank to measure hydrostatic pressure. The low-pressure input of the differential pressure transducer is connected to the vapor space pressure. The transducer subtracts the vapor pressure from the high-pressure. Resulting is a value that represents the hydrostatic head proportional to the liquid level.

Thursday, August 3, 2017

Pressure Sensor Accessories - Filled Impulse Line

welded isolating diaphragm for pressure sensing line
An isolating diaphragm, such as this variety
pictured, can be used as a barrier between
process fluid and sensing line fill.
Image courtesy REO Temp 
Pressure sensors intended for use in industrial process measurement and control applications are designed to be robust, dependable, and precise. Sometimes, though, it is necessary or beneficial to incorporate accessories in an installation which augment the performance of pressure sensors in difficult or hazardous environments. There are some scenarios where the sensor must be isolated from the process fluid, such as when the substance is highly corrosive or otherwise damaging to the pressure sensor.

A way to aid pressure sensing instruments in situations where direct contact must be avoided is by using a filled impulse line. An impulse line extends from a process pipe of vessel to a pressure measurement instrument or sensor. The line can have a diaphragm barrier that isolates the process fluid from the line, or the line can be open to the process. There are best practices that should be followed in the design and installation of an impulse line to assure that the line provides a useful transmission of the process pressure to the sensor and whatever degree of isolation or protection is needed remains in effect.

The filled impulse line functions via the addition of a non-harmful, neutral fluid to the impulse line. The neutral fluid acts as a barrier and a bridge, allowing the pressure sensing instrument to measure the pressure of the potentially harmful process fluid without direct contact. An example of this technique being employed is adding glycerin as a neutral fluid to an impulse line below a water pipe.

Glycerin's freeze point is lower than waters, meaning glycerin can withstand lower temperatures before freezing. The impulse line connected to the water pipe may freeze in process environments where the weather is exceptionally cold, since the impulse line will not be flowing in the same way as the water pipe. Since glycerin has a greater density and a lower freezing point, the glycerin will remain static inside the impulse line and protect the line from hazardous conditions.
pressure transmitter
Filled impulse lines protect pressure
transmitters from the adverse impact
of aggressive process fluids.


The use of an isolating diaphragm negates the need for certain considerations of fill fluid density, piping layout, and the need to create an arrangement that holds the fill fluid in place within the impulse line. System pressure will be transferred across the diaphragm from the process fluid to the fill fluid, then to the pressure sensor. It is important to utilize fluids and piping arrangements that do not affect the accurate transference of the process pressure. Any impact related to the impulse line assembly must be determined, and appropriate calibration offset applied to the pressure sensor reading.

An essential design element of a filled impulse line without an isolating diaphragm is that the fill fluid must be compatible with the process fluid, meaning there can be no chemical reactivity between the two. Additionally, the two fluids should be incapable of mixing no matter how much of each fluid is involved in the combination. Even with isolating diaphragms employed, fluid harmony should still be considered because a diaphragm could potentially loose its seal. If such a break were to occur, the fluids used in filled impulse lines may contact the process fluid, with an impact that should be clearly understood through a careful evaluation.

Monday, April 10, 2017

Introduction to Transmitters

Process transmitters
Flow transmitter (FCI)
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 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. 
Pressure transmitter
Pressure transmitter
(Yokogawa)
Output signals for 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 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.

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.

Friday, December 9, 2016

Portable Gas Detectors For Industrial Applications



This video covers the Servomex line of portable gas analyzers that can be utilized as benchtop units or true carry around portables. Servomex has a long history of solid instrument performance and innovation in gas detection and analysis.

Share your gas detection and analysis requirements and challenges with an application specialist, combining your process knowledge with their product application expertise to develop effective solutions.

Thursday, November 17, 2016

Applying Turbine Flow Meters For Clean Liquids and Gases

turbine flow meter flange connections Hoffer
Turbine Flow Meter
Courtesy Hoffer Flow Controls 
A turbine flow meter provides a volumetric measurement of liquid or gas flow through the use of a vaned rotor (turbine) inserted in the fluid flow path. Fluid movement causes the turbine to rotate at an angular velocity proportional to the flow rate. A pickup senses the passage of the rotor vanes, producing a sine wave electrical signal output which is detected by the unit electronics. The frequency of the signal relates directly to the flow rate.

Generally, a turbine flow meter is applied to measure unidirectional flow. Some turbine flow meters, through the use of two pickups, have the capability to measure flow in both directions.

There are a number of considerations when selecting a turbine flow meter:

  • Material of construction: Numerous material options are available for the housing and internal parts. Proper selection considers media characteristics and cost.
  • Bearing selection: The combination of bearing type and material will likely be selected by the device manufacturer, based upon a comprehensive application information set.
  • Pickup selection: Several pickup options may be available, with the manufacturer making a recommendation that best suits the application parameters.
turbine flow meter installation schematic
Typical Turbine Flow Meter Installation Schematic
Courtesy Hoffer Flow Controls
Here are a few other things to consider about applying turbine flow meters:
  • Turbine flow meters are precision instruments and will not tolerate debris well. An installation should include a strainer configured to trap debris that may damage the instrument of hinder its operation.
  • For longevity, it is advisable to size the flow meter to avoid extended operation near the upper end of its rotational range. Excessive rotational speeds can accelerate wear on bearings.
  • Lower rotor mass will provide more rapid response to changes in flow, allowing use of the device in applications with flow pulsations.
  • Maintain sufficient downstream pressure to prevent flashing or cavitation. This condition will cause the instrument to produce readings higher than the actual flow rate.
  • Sufficient straight pipe length should be installed at the inlet and outlet of the flow meter to provide flow conditioning necessary for accurate readings. In some cases, a flow staightener may be needed on the upstream side.
  • The output signal from the pickup may need amplification or other signal conditioning. Electrically noisy environments or long cable lengths may require special treatment.
Careful consideration of what is necessary for proper operation will pay off with reliable and accurate performance, low maintenance, and a long service life. Share your flow measurement challenges with product application experts, combining your process knowledge with their product application expertise to develop effective solutions.


Wednesday, November 9, 2016

Box-In-Box Coriolis Flow Meter Design Explained



Yokogawa, manufacturer of the Rotomass Coriolis Flow Meter utilizing the patented "box-in-box" design, has produced a short video explaining how their design counteracts some of the environmental and process piping conditions that can negatively impact measurement of fluid flow. On Coriolis type flow instruments, conditions that apply stress to the sensor tube assembly can change the resonant frequency of the assembly, impacting the measured reading. The Yokogawa design employs a means to minimize or eliminate their effect, maintaining accurate measurement of flow in process piping.

Share your flow measurement challenges and requirements with product application specialists, combining your process knowledge with their application expertise to develop effective solutions.

Wednesday, November 2, 2016

Direct Drive Pressure Gauges for the Rugged Industrial Applications

direct drive industrial pressure gauge
Direct Drive Industrial Pressure Gauge
Wika - 3D Instruments
Pressure indication, on location, real time. That is what a dial pressure gauge provides a process operator. Pressure gauges do not require any type of operating power, making them immune to power failures. The Bourdon tube mechanical operator is generally rugged and reliable. They are, however, subject to wear in the linkage that connects the Bourdon tube to the indicator needle over time. Extremes of vibration will also likely impact the longevity of the linkage, leading to premature failure.

3D Instruments, a manufacturer of pressure gauges and related products for industrial, commercial, and scientific applications, has developed a direct drive pressure gauge intended for use in the most rugged and demanding applications. The direct drive pressure gauges have only one working part, a helically-wound Bourdon tube made of Inconel® X-750, a flexible material that prevents the coil from losing its shape and ensures accuracy. The indicating needle is directly connected to the Bourdon tube, eliminating linkage parts. This innovation, while maintaining the benefits of some of the oldest pressure measurement technology, adds improvements in overpressure protection, burst protection, wear resistance, and life cycle cost.

A short video, included below, highlights and illustrates how the direct drive system works. Reach out to a process measurement product specialist for more detail, or solutions to any of your measurement and control challenges.

Tuesday, August 9, 2016

Non-contact, Radiometric Level Detection for Liquids or Solids

Radiometric level detection
Radiometric level detection
(courtesy of RONAN)
Radiometric level detection, using a very low gamma level source, is designed to deliver outstanding performance in a wide range of difficult applications and process conditions for both liquids and bulk solids which include the most dangerous materials such as caustic, toxic, corrosive, explosive, and carcinogenic irrespective of their viscosity and temperature.

These level gauges meet “As-Low-As-Reasonably-Achievable” (ALARA) guidelines. Source activity is customized depending on vessel and process parameters such as diameter, wall thickness, material, and measurement span to ensure optimum sensitivity, economy and safety while keeping the source activity to a minimum.

An exclusive “Radiation Low Level” (RLL) source holder uses up to 100 times less gamma energy than comparable gauges, and is the only source holder recognized by the NRC to be so safe that it does not require the stringent documentation, training or handling procedures of other systems.

How it Works

Radiometric level detection
Sources and Detector Mounted
External to Vessel 
Radiometric level measurement provides a safe and efficient, non-contact method to measure liquids or solids in harsh process environments. Each system consists of a gamma source, detector and microprocessor.
  • The gamma source, typically mounted external to the vessel emits energy through the vessel walls collimated in a direction towards the detector mounted on the opposite side of the vessel. The gamma energy reaches the detector when the vessel is empty. As the process level rises in the vessel, the gamma energy reaching the detector will decrease in an inversely proportional relationship to the level. 
  • The detector measures the level of energy and sends a proportional signal to the microprocessor. 
  • The microprocessor linearizes, filters, and correlates this signal to a level measurement. 
The entire system is mounted external to the vessel and can be easily installed and maintained while the process is running ... without expensive down time, vessel modifications or chance of accidental release.

Applications
Radiometric level detection
Low Level Source and Detector
Mounted External to Vessel

  • Solids or Liquid Measurement 
  • Measurement Not Affected by: 
  • Internal Obstructions. i.e. Agitators Extreme Process Temperatures 
  • Caustic Processes 
  • Violent Product Flow 
  • Sterile Process 
  • Changing Process 
  • Variable Product Flow 
  • Automatic Compensation for Vapor Density Changes 
  • Automatic Compensation for Foam or Gasses 
  • Automatic Compensation for Process Build-Up 
  • Detectors Contoured to the Shape of Vessels 
  • Upgrade Utilizing Existing Sources 
Features and Benefits
  • Accurately Measures the Most Complex Processes 
  • Solid Crystal or Flexible Scintillating Fill- Fluid 
  • Excellent Measurement Reliability due to Proprietary Filtering Technology 
  • Level Detection of Multiple Interfaces 
  • Low Maintenance / No Component Wear 
  • Auto-Calibration
For more information in Maryland or Virginia, contact:
Flow-Tech
410-666-3200 MD
804-752-3450 VA

Monday, January 11, 2016

Mass Flow Rate and More From Multivariable Transmitter - Process Measurement and Control

Multivariable mass flow measurement transmitter
Model EJX 910A Multivariable Transmitter
Courtesy of Yokogawa
Industrial process measurement and control is charged with continually producing better, faster, and cheaper results with increasing levels of safety. For applications requiring mass flow rate measurement of fluids or tank level, a multivariable transmitter has much to offer when it comes to improving outcomes throughout your industrial process operation.

The EJX 910 series from Yokogawa provides the latest generation of digital sensing and processing to provide fast and accurate process measurement of temperature, static pressure, differential pressure, and dynamically compensated mass flow. Flow accuracy as high as +/-1.0% is achievable, along with:

±0.04% Differential Pressure Accuracy
±0.1% Static Pressure Accuracy
±0.9°F External Temperature Accuracy



Some other highlights include:

  •  Industry leading fast response time for safe and accurate process control.
  • Yokogawa's specially developed DPharp digital sensor providing simultaneous static and differential pressure measurement, digital accuracy, and no A/D conversion error.
  • LCD display can be rotated in 90 degree increments. External zero adjustment screw and range setting switch enhance field setup.
  • Improved mass flow accuracy of +/- 1% from multivariable operation in one device with dynamic compensation.
  • Signal characterizer for measuring level in irregular shaped tanks.
  • Utilizes industry recognized open communication protocols for easy integration into existing installations.

The manufacturer's white paper, describing precisely how the unit works and how it can be applied, is below. Browse the white paper for some additional detail, but consult with a product specialist to explore how to improve your process measurement and control performance. They have even more information than is provided here which, when combined with your process knowledge, is sure to generate a positive solution to any challenge.



Process Control - Five Categories of Instrument Protection


Industrial process temperature and pressure gauges
Instrument protection is a key element of process design
and equipment layout
The performance of every process is critical to something or someone. Keeping a process operating within specification requires measurement, and it requires some element of control. The devices we use to measure process variables, while necessary and critical in their own right, are also a possible source of failure for the process itself. Lose the output of your process instrumentation and you can incur substantial consequences ranging from minor to near catastrophic.

Just as your PLC or other master control system emulates decision patterns regarding the process, the measurement instrumentation functions as the sensory input array to that decision making device. Careful consideration when designing the instrumentation layout, as well as reviewing these five common sense recommendations will help you avoid instrument and process downtime.

Process generated extremes can make your device fail.


Search and plan for potential vibration, shock, temperature, pressure, or other excursions from the normal operating range that might result from normal or unexpected operation of the process equipment. Develop knowledge about what the possible process conditions might be, given the capabilities of the installed process machinery. Consult with instrument vendors about protective devices that can be installed to provide additional layers of protection for valuable instruments. Often, the protective devices are simple and relatively inexpensive.


Don't forget about the weather.


Certainly, if you have any part of the process installed outdoors, you need to be familiar with the range of possible weather conditions. Weather data is available for almost anywhere in the world, certainly in the developed world. Find out what the most extreme conditions have been at the installation site....ever. Planning and designing for improbable conditions, even adding headroom, can keep your process up when the unexpected occurs
.
Keep in mind, also, that outdoor conditions can impact indoor conditions in buildings without climate control systems that maintain a steady state. This can be especially important when considering moisture content of the indoor air and potential for condensate to accumulate on instrument housings and electrical components. Extreme conditions of condensing atmospheric moisture can produce dripping water.

Know the security exposure of your devices.


With the prevalence of networked devices, consideration of who might commit acts of malice against the process or its stakeholders, and how they might go about it, should be an element of all project designs. A real or virtual intruder's ability to impact process operation through its measuring devices should be well understood. With that understanding, barriers can be put in place to detect or prevent any occurrences.

Physical contact hazards


Strike a balance between convenience and safety for measurement instrumentation. Access for calibration, maintenance, or observation are needed, but avoiding placement of devices in areas of human traffic can deliver good returns by reducing the probability of damage to the instruments. Everybody is trained, everybody is careful, but uncontrolled carts, dropped tools and boxes, and a host of other unexpected mishaps do happen from time to time, with the power to inject disorder into your world. Consider guards and physical barriers as additional layers of insurance.

Know moisture.


Electronics must be protected from harmful effects of moisture. Where there is air, there is usually moisture. Certain conditions related to weather or process operation may result in moisture laden air that can enter device enclosures. Guarding against the formation of condensate on electronics, and providing for the automatic discharge of any accumulated liquid is essential to avoiding failure. Many instrument enclosures are provided with a means to discharge moisture. Make sure installation instructions are followed and alterations are not made that inadvertently disable these functions. Moisture also is a factor in corrosion of metal parts. Be mindful of the extra degree of protection provided by special coatings or materials that may be options for your instruments.


Developing a thoughtful installation plan, along with reasonable maintenance, will result in an industrial process that is hardened against a long list of potential malfunctions. Discuss your application concerns with a knowledgeable instrument sales engineer. Their exposure to many different installations and applications, combined with your knowledge of the process and local conditions, will produce a positive outcome.

Thursday, December 31, 2015

Soil, Water, Air and Technical Gas Testing with Draeger Tubes

Draeger Tube
Draeger Tube and Analyzer
Natural, ambient air is chemically a gas mixture that consists of 78 % nitrogen, 21 % oxygen 0.03% carbon dioxide as well as argon, helium and other rare gases in trace concentrations. In addition there is water vapor, e. g. humidity. If the concentrations of the components change, or a foreign gas is added, we no longer have natural air. When these changes occur, the potential for adverse health effects exist.

The spectrum of other so-called air components can be extremely broad. It can range from the pleasant fragrance of a good perfume to the over powering stench of hydrogen sulfide. Likewise, the hazard of each “air pollutant” varies considerably. The type of substance, its concentration and duration of occurrence, as well as probable synergistic effects with certain gas compounds must all be considered. In addition, there are many air pollutants which cannot be perceived by human senses because they are colorless and odorless (e. g. carbon monoxide).

If the composition of the natural air changes in any way, it should be tested, to determine the substance which caused this change. Even substances with distinctive odors cannot be reliably assessed with the aid of the olfactory nerve in the nose. The olfactory nerve can become desensitized after a certain period of time or repeated exposure, making it impossible to smell even immediately dangerous concentrations. After a few hours we do not even perceive the pleasant fragrance of our own perfume and high concentrations of hydrogen sulfide escape from the sense of smell even after a very short while.

Subjectively, one persons sense of smell may be more sensitive to certain air pollutants than others. In many cases substances are noticed in very low concentrations which, even after a long-term exposure do not necessarily cause adverse health effects. In general the sense of smell is sufficient in determining the presence of air pollutants, but the need exists for an objective gas analysis method. Gas measurement serves as a technical aid and an assessment of the concentration is only possible with a gas measurement device. To determine the hazard potential of a gas it is necessary to measure its concentration and to consider the duration of exposure and other parameters such as the type of work being performed.

If only the concentration of an air pollutant is known it is difficult to evaluate the degree of the hazard. For Example, there is a degree of uncertainty regarding the health effects of cigarette smoking. The synergistic effect of the more than 800 single substances in cigarette smoke and the physiological condition of the smoker are all factors in determining the toxicological influence to the individual.

An important prerequisite to determining the potential of any gaseous air pollutants is the determination of the concentration with a suitable gas measurement device. The kind of device to be used depends on which gases have to be measured and how often. Much to the dismay of both the user and the manufacturer, there is no universal instrument which measures all gases or vapors. The variety of substances is too wide for a single technique to measure all possible air pollutants. The more chemically complex a substance is, the more complex the gas measurement technique.

It may be that more than one measurement device or measurement method may be employed, each based on different operational principles. The instrumentation industry offers various devices for this purpose which can be used, individually or in combination on the measurement task:
  • flame ionization detectors - photo ionization detectors - gas chromatographs
  • infrared spectrometers 
  • UV-VIS photometers
  • warning devices for explosion hazards
  • Dräger-Tubes
  • Dräger Chip-Measurement-System
  • laboratory analysis in conjunction with sampling tubes or gas wash bottles (impinger) - mass spectrometers
  • substance selective instruments with e. g. electrochemical sensors
To read more, or download the entire handbook, see below:

Friday, December 4, 2015

Interesting Facts About Differential Pressure Cone Flow Meters

industrial differential pressure flow measurement device
Differential Pressure Cone Flow Meter
Courtesy McCrometer, Inc.
Requirements for measurement of flow exist throughout the industrial process control field. The applications are varied and vast. As a result, there are a number of technologies available for flow measurement and an even larger array of manufacturers providing devices and instrumentation that can be used to measure fluid flow.

Selecting the measurement technology that will provide appropriate performance for a process measurement application is an initial challenge for every process design. In order to accomplish this task, it follows that a well rounded understanding of the potentially positive or negative attributes for each methodology is necessary.

Differential pressure is one method of indirectly measuring fluid flow. It measures the change in pressure created as media flows past an obstruction in the fluid path, which, when combined with other information and calculation can be used to derive a measurement of mass flow. Like all measurement methods, there are applications where this one excels over others and some where it may not be as advantageous as alternate methods.

One manufacturer of differential pressure flow measurement devices is McCrometer. The company has been manufacturing DP flow measurement devices for over thirty years and has over 75,000 installations worldwide. In the company's own words, their flagship V-Cone product...
is an advanced differential pressure instrument, which is ideal for use with liquid, steam or gas media in rugged conditions where accuracy, low maintenance and cost are important.
Cutaway view of industrial cone flow meter
Cone Meter - Cutaway view
Courtesy McCrometer, Inc.
I have included below an interesting piece that provides, in brief form, some facts that will add to your knowledge of cone meters. Read the piece below. Contact a product specialist for any additional information you may need, or to discuss how this technology can make a positive impact on your industrial process measurement operations.



Wednesday, November 11, 2015

Well Grounded Knowledge for Industrial Control - Part Three of Three

Drawing symbol for electrical ground connection
Drawing Symbol for Electrical Ground Connection

This is the third part of a three part series of white papers intended to boost or reinforce your knowledge of electrical grounding for industrial process measurement and control.

Part One and Part Two were previously posted in this blog and you would be best served to read all three papers in sequence.

The series was exceptionally well written by the folks at Acromag, a world class manufacturer of industrial I/O devices.

Your questions or concerns about any aspect of your industrial process control or measurement applications are always welcome. Contact us and we will work with you to formulate a solution to a process measurement and control challenge.


Well Grounded Knowledge for Industrial Control - Part Two of Three

Electrical drawing symbol for ground connection
Drawing Symbol for Electrical Ground Connection
The use of electric power to perform work, whether using large motors or sensitive instrumentation, involves benefits and hazards. In modern society, preventing exposure of equipment and appliance users to electric shock is universally accepted as a mandate imposed upon manufacturers, installers, and operators of electrical equipment. Proper electrical grounding serves as a key element in maintaining the level of safe operation we all want to have in our facilities.

One manufacturer of industrial process control I/O devices, Acromag, has expertly written three white papers in a series providing non-technical tutorials and explanations on the subject of electrical grounding and its integral role in safety and operational integrity.
Some topics covered include:
  • The safety function of a ground connection
  • Operation of a ground fault circuit interrupter (GFCI)
  • How electrical ground can stabilize voltage and limit transients
  • Recommendations for improvement of safety and signal integrity   
  • Importance of circuit grounding
  • AC power in the United States and its use of earth ground
Part One was published previously, and it is advisable to review the three parts in sequence. The third installment follows this post. This is recommended reading for all technical levels. Industrial process measurement and control stakeholders will all benefit, whether from newly acquired knowledge or refreshed understanding of the subject.

Product and application specialists are always eager to hear about your application issues and questions. Never hesitate to contact them. Your process knowledge, combined with the product and application familiarity of a professional sales engineer, will generate good outcomes.


Well Grounded Knowledge for Industrial Control - Part One of Three

Drawing symbol for electrical ground connection
Drawing Symbol for Electrical Ground
I suspect that most control system techs have, at one time or another, come face to face with control or instrument behavior that seemed bizarre and intractable. Maybe strange behavior would come and go with no apparent explanation. Instruments or control equipment would work properly for a while, then inexplicably go south. You carefully observe illogical operation occurring without any apparent cause, and sorting it out proves to be very difficult. This is not a situation in which you want to find yourself as a service technician, operator, or vendor, particularly when process stakeholders, like your boss or customer, are observing your progress.

While many of these stories may illicit laughter when retold as history, at the time they are serious business and nobody is laughing. If you want to avoid these sweat stain inducng situations in your career, one subject on which you should be well versed is electrical grounding of your industrial process equipment and instruments. Whether a tech, vendor, or operator, solid basic knowledge about grounding principals and techniques will help you to assure the safety of personnel and equipment in your work area and keep instrumentation and controls operating as intended.

This first of three installments is shown below, expertly written by the engineers at Acromag, a world class manufacturer of I/O devices for industrial process measurement and control.  Part Two and Part Three will be published in successive posts. I recommend these white papers for all technical levels as newly acquired knowledge or refresher. This is subject matter that applies universally. Be sure to read Part Two and Part Three.

Application assistance is always available from knowledgeable sales engineers specializing in process measurement and control. The best solution to an application challenge will arise from a combination of your process mastery and the product knowledge and technical resources of your respected vendors.