Introduction to a Closed Loop Control System

Closed Loop Control System

The video below explains the concept of a closed loop control system, using a steam heat exchanger and food processing application as an example.

A closed loop control system uses a sensor that feeds current system information back to a controller. That information is then compared to a reference point or desired state. Finally, a a corrective signal is sent to a control element that attempts to make the system achieve its desired state.

A very basic example of a temperature control loop includes a tank filled with product (the process variable), a thermocouple (the sensor), a thermostat (the controller), and a steam control valve feeding a tubing bundle (the final control element).

The video outlines all the major parts of the system, including the measured variable, the set point, the controlled variable, controller, error and disturbance.

Contact http://www.ivesequipment.com with any process control or instrumentation requirement. Call 877-768-1600 for immediate assistance.

Level Instrumentation for Your Entire Industrial Plant

Siemens level controls.

Whether you are measuring liquids, slurries or bulk solids, Siemens provides the ideal level measuring instruments for every job. Siemens level measurement devices set the standard in their respective disciplines for water, cement, mining, chemical, petrochemicals, food, beverage, pharmaceutical and other industries.

Point Level

Siemens level switches for point level measurement are distinguished by their outstanding performance. Their robust design ensures reduced cost of maintenance, spare parts, and downtime. Siemens level measurement instruments offer easy commissioning, connection to alarm or control systems, long service life, and low operating costs. Technologies include capacitance, rotary paddle, ultrasonic and vibrating.

Continuous

The product portfolio for continuous level measurement covers both contacting and non-contacting measurement. Radar, ultrasonic and gravimetric technologies are available for the non-contacting applications. Capacitance, guided wave radar and hydrostatic technologies are available for the contacting applications. As well, don’t forget that the safest engineered level measurement solution includes switches for back-up, overfill, low level and dry run protection. Technologies include radar, guided wave radar, ultrasonic, gravimetric, capacitance, and hydrostatic.

Interface

Siemens broad portfolio includes a large number of devices for many interface measurement applications, and includes the following products. SITRANS LC500, Pointek CLS 100, CLS 200, CLS 300 and CLS 500 are capacitance instruments for a wide range of tasks. The SITRANS LG uses guided wave radar technology.

Watch the entertaining video below to get a better idea of what level solutions Siemens (and Ives) has to offer.

Monitoring Catalyst Presulfiding

Catalyst ‘presulfiding’ is a practice which reduces the extent of early catalyst deactivation on by preventing coking (carbon deposits). The procedure involves passing a gas stream containing H₂S over the catalyst or into the reaction feedstock.

In order to generate the H₂S which will interact with the catalyst, a sulfur carrying agent (e.g. dimethyl sulfide) is injected into the stream. Under high temperature and catalytic reaction, the agent decomposes and releases its sulfur component, forming H₂S. The H₂S reacts with the catalyst’s metallic surface to substitute sulfur atoms for oxygen atoms.

Read the document below to learn more about monitoring this process with the Applied Analytics OMA-300 H₂S Analyzer

Monitoring Catalyst Presulfiding Step from Ives Equipment

Ives Equipment Business Groups

Ives Equipment organizes its extensive product line into four distinct groups:

Ives Equipment and Controls, providing instrumentation and control products to the chemical, petro-chemical, refining, bulk storage, primary metals, pulp & paper, powergen, gas & oil distribution and OEM markets.

Pharmaceutical, Bio-pharm, and Sanitary, providing hygienic, ultra-pure and sanitary instruments, connectors, fittings, tubing and gaskets to the pharma, bio-pharm, food and beverage, life-science and labortory industries.

Analytical Instruments, used to analyze process material samples and record the data for quality, conformance and compliance.

Water and Wastewater Treatment, providing instruments, analyzers, valves and controls for the transfer, storage, analysis, treatment, and logging of municipal and industrial water treatment systems.

Definition: Industrial Valve Actuator

Pneumatic actuator on ball valve.
(Worcester)

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.

Electric actuator (Worcester)

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.

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.

Electro-hydraulic actuator
(MIH Trident)

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.

Contact Ives Equipment for any valve actuator application. Visit http://www.ivesequipment.com or call (877) 768-1600.

Principles of Ultrasonic Flow in Industrial Clamp On Flow Meters

The video below demonstrate the principles applied to industrial clamp on flow meters using the SITRANS FS as an example.

The ultrasonic technology of the SITRANS clamp on flow meter provides highly accurate measurement of liquids and gases. With no pressure drop or energy loss, a wide turn-down ratio and no need to cut the pipe or stop the flow, installation is easy and maintenance is minimal.

For more information about ultrasonic flow meters, contact Ives Equipment at 877-768-1600 or visit http://www.ivesequipment.com.

Refinery Gas Analyses Using Compact Gas Chromatographs and Gas Detectors

The analysis of trace permanent gases has many different fields of application in the petrochemical industry. One of the most important is for controlling the manufacturing process and the product quality. For example, some contaminants as carbon monoxide and carbon dioxide tend to deteriorate the catalysts in the propylene and ethylene polymer grade production.

An instrument for monitoring trace impurities is then required. Many different GC techniques are available on the market. Most of the techniques use a combination of TCD, FID and methanizer for the trace analysis of H2-O2-N2-CH4-CO-CO2 in propylene and ethylene. More precisely, an FID and a methanizer are used to trace CH4-CO and CO2. A TCD with Hydrogen or Helium carrier gas is used to trace O2-N2 detection. Finally, a second TCD with Argon or Nitrogen carrier gas must be added to trace H2 detection. These solutions require complex GC solutions with multiple detectors and multiple gas sources for carrier, fuel and air. On top of that, an FPD must be added in some cases when the trace analysis of H2S is required.

Read the application note below for more information. Contact Ives Equipment at (877) 768-1600 or visit http://www.ivesequipment.com for a consultation.

Refinery Gas Analyses with Multidetek2 Compact Gas Chromatograph and Plasmadetek2 Gas Detector from Ives Equipment

Understanding Hydrostatic Pressure

Pressure measurement is an inferential way to determine the height of a column of liquid in a vessel in process control. The vertical height of the fluid is directly proportional to the pressure at the bottom of the column, meaning the amount of pressure at the bottom of the column, due to gravity, relies on a constant to indicate a measurement. Regardless of whether the vessel is shaped like a funnel, a tube, a rectangle, or a concave polygon, the relationship between the height of the column and the accumulated fluid pressure is constant. Weight density depends on the liquid being measured, but the same method is used to determine the pressure.

A common method for measuring hydrostatic pressure is a simple gauge. The gauge is installed at the bottom of a vessel containing a column of liquid and returns a measurement in force per unit area units, such as PSI. Gauges can also be calibrated to return measurement in units representing the height of liquid since the linear relationship between the liquid height and the pressure. The particular density of a liquid allows for a calculation of specific gravity, which expresses how dense the liquid is when compared to water. Calculating the level or depth of a column of milk in a food and beverage industry storage vessel requires the hydrostatic pressure and the density of the milk. With these values, along with some constants, the depth of the liquid can be calculated.

The liquid depth measurement can be combined with known dimensions of the holding vessel to calculate the volume of liquid in the container. One measurement is made and combined with a host of constants to determine liquid volume. The density of the liquid must be constant in order for this method to be effective. Density variation would render the hydrostatic pressure measurement unreliable, so the method is best applied to operations where the liquid density is known and constant.

Interestingly, changes in liquid density will have no effect on measurement of liquid mass as opposed to volume as long as the area of the vessel being used to store the liquid remains constant. If a liquid inside a vessel that’s partially full were to experience a temperature increase, resulting in an expansion of volume with correspondingly lower density, the transmitter will be able to still calculate the exact mass of the liquid since the increase in the physical amount of liquid is proportional to a decrease in the liquid’s density. The intersecting relationships between the process variables in hydrostatic pressure measurement demonstrate both the flexibility of process instrumentation and how consistently reliable measurements depend on a number of process related factors.

For more information on any type of pressure instrumentation, visit Ives Equipment at http://www.ivesequipment.com or call 877-768-1600.

An Explanation of Industrial Process Heating Technologies

Boiler providing steam for process heat.

Process heating technologies can be grouped into four general categories based on the type of fuel consumed: fuel, steam, electric, and hybrid systems (which utilize a combination of energy types). These technologies are based upon conduction, convection, or radiative heat transfer mechanisms - or some combination of these. In practice, lower-temperature processes tend to use conduction or convection, whereas high-temperature processes rely primarily on radiative heat transfer. Systems using each of the four energy types can be characterized as follows:

Fuel-based process heating systems generate heat by combusting solid, liquid, or gaseous fuels, then transferring the heat directly or indirectly to the material. Hot combustion gases are either placed in direct contact with the material (i.e., direct heating via convection) or routed through radiant burner tubes or panels that rely on radiant heat transfer to keep the gases separate from the material (i.e., indirect heating).  Examples of fuel-based process heating equipment include furnaces, ovens, red heaters, kilns, melters, and high-temperature generators.

Steam-based process heating systems introduce steam to the process either directly (e.g., steam sparging) or indirectly through a heat transfer mechanism. Large quantities of latent heat from steam can be transferred efficiently at a constant temperature, useful for many process heating applications. Steam-based systems are predominantly used by industries that have a heat supply at or below about 400°F and access to low-cost fuel or byproducts for use in generating the steam. Cogeneration (simultaneous production of steam and electrical power) systems also commonly use steam-based heating systems. Examples of steam-based process heating technologies include boilers, steam spargers, steam-heated dryers, water or slurry heaters, and fluid heating systems.

Electricity-based process heating systems also transform materials through direct and indirect processes. For example, electric current is applied directly to suitable materials to achieve direct resistance heating; alternatively, high-frequency energy can be inductively coupled to suitable materials to achieve indirect heating. Electricity-based process heating systems are used for heating, drying, curing, melting, and forming. Examples of electricity-based process heating technologies include electric arc furnace technology, infrared radiation, induction heating, radio frequency drying, laser heating, and microwave processing.

Hybrid process heating systems utilize a combination of process heating technologies based on different energy sources and/or heating principles to optimize energy performance and increase overall thermal efficiency. For example, a hybrid boiler system may combine a fuel-based boiler with an electric boiler to take advantage of access to lower off-peak electricity prices. In an example of a hybrid drying system, electromagnetic energy (e.g., microwave or radio frequency) may be combined with convective hot air to accelerate drying processes; selectively targeting moisture with the penetrating electromagnetic energy can improve the speed, efficiency, and product quality as compared to a drying process based solely on convection, which can be rate-limited by the thermal conductivity of the material. Optimizing the heat transfer mechanisms in hybrid systems offers a significant opportunity to reduce energy consumption, increase speed/throughput, and improve product quality.

For more information, visit www.ivesequipment.com or call (877) 768-1600.

An Industrial Valve Positioner that Offers Decisive Advantages

The SIPART ® PS2 electro-pneumatic valve positioner is used to control the final control element of pneumatic linear or part-turn valve actuators. The electro-pneumatic valve positioner moves the actuator to a valve position corresponding to the setpoint. Additional function inputs can be used to block the valve or to set a safety position. A binary input is present as standard in the basic device for this purpose.

The SIPART PS2 smart valve positioner is characterized by significant advantages compared to conventional devices, such as:

• Only one device version for linear and part-turn valve actuators
• Simple operation and programming using three keys and a two-line LCD
• Automatic startup function with self-adjustment of zero and span
• Manual operation without additional equipment
• Selectable or freely-programmable characteristics
• Minimum air consumption
• Selectable setpoint and manipulated variable limiting
• Programmable "tight shut-off function"

For more information about the Siemens SIPART 2 positioner download the detailed product brochure from this link,  or visit http://www.ivesequipment.com.

Upgrading to a United Electric (UE) Controls One Series from a Mechanical Pressure Switch

This video below demonstrates how to replace an older on/off mechanical pressure switch and install the UE One Series.

The One Series electronic pressure and temperature transmitter-switches set the standard for smart digital process monitoring. With a fully adjustable set point and deadband and 0.1% repeatability, the One Series performs in a wide variety of applications. Available in Type 4X enclosures approved for intrinsic safety, flameproof and non-incendive area classifications, these hybrid transmitter-switches are designed to provide transmitter, switch and gauge functions all-in-one rugged enclosure that can withstand the rigors of harsh and hazardous environments.

Each One Series model incorporates intelligent self-diagnostics and can report detected faults before they become major safety issues. Plug Port Detection protects against sensor clogging. Nuisance trip filtering reduces false and spurious signals. The ability to capture pressure spikes and valleys provides process information to aid in the commissioning and debugging process.

For more information, visit http://www.ivesequipment.com or call (877) 768-1600.

Remote Telemetry Outstation / Data Logger for Water Utilities

Technolog Cello 4S data logger.

The Technolog Cello 4S data logger monitors, records and transmits multiple site parameters over 2G (SMS/GPRS) or 3G networks, and provides a comprehensive multi-application solution for the Water Utilities and Industry.

The Cello 4S can have up to two pressure, eight user programmable digital or analogue inputs and two individually switched 12 Volt outputs for powering 4-20mA loops. Setup is made easy through an optional WiFi communication interface, and remote set-up, monitoring and control is facilitated through locally deployed PMAC software or web based WaterCore platform.

Technolog Cello 4S installed.

The Cello 4S provides closed loop control of pressure reducing valves, pressure sustaining valves and variable speed pumps, high accuracy battery monitoring for optimal asset management, is housed in a sturdy, portable, and waterproof to IP68 enclosure, offers 5 year battery life (typically) and includes water temperature measurement.

Download a specification sheet directly from the Ives Equipment website here.

Or, view the specification sheet below:

Technolog Water Utility Datalogger Cello 4S from Ives Equipment

Advanced Safety Integrity Universal Gas Transmitter

The Sensidyne SensAlert ASI provides enhanced protection and dependability for critical safety applications where personnel, processes, and facilities are at risk. The third-party certified SIL-2 SensAlert ASI offers dependability and versatility while remaining the easiest to install, commission, operate, and maintain.

SensAlert ASI is third-party certified to IEC61508 Level 2 (SIL-2) for both hardware and software with certification to global hazardous area and performance standards. The Test-on-Demand feature with on-board gas generator provides remote functionality checks with generated gas while Predictive Sensor End-of-Life Indication provides advanced warning of impending sensor failure.

For your convenience, we have posted the SensAlert ASI Users Manual below.

SensAlert ASI Advanced Safety Integrity Gas Transmitter from Ives Equipment

Vibrating Point Level Switch Operating Principles and Use

Vibrating point level switches (SIEMENS)

When asked the primary reason to remember the year 1711, the event probably not on the minds of many is the invention of a device called the tuning fork. The tuning fork has been used as an source of resonating pitch for over three hundred years, and is still used to tune musical instruments today. While the tuning fork was initially applied to tune musical instruments, the concept of resonant frequency of a material or object has been utilized in numerous commercial, scientific, and industrial applications to provide feedback or insight into a process or operation. The vibrating fork level switch is one such industrial application where resonant frequency is used to deliver a data point or provide a control output for process operation.

The operating principle of the vibrating fork is based on the oscillating fork resonating at a known frequency in air when it is set in motion. Upon contacting a medium other than air, the resonant frequency is shifted, depending on the medium contacting or immersing the fork. Typically, fork-type level switches are installed on either the side or the top of a liquid process tank. An exciter keeps the fork oscillating, and a detector circuit monitors fork vibrating frequency, providing a change in the output signal when the frequency changes. Contact or immersion of the fork in liquid will change the fork vibrating frequency sufficiently to produce a change in output signal. Depending on the configuration of the level switch, it can function as a liquid level alarm, or provide a control output for a pump, valve, or other device. Sensor response, the change in fork vibration frequency, is a function of liquid density. Liquids with greater density will generally produce a larger frequency shift in the vibrating fork.

The wide use of vibrating level switches across various process industries is a testament to the reliability of the technology. The devices protect against overfill, indicate high and low points inside tanks, and are useful over a wide range of temperatures. A sturdy design, coupled with product variants that include a variety of sensor materials, selectable probe length, and specialized output features make vibrating fork switches applicable in many operations where level indication is needed. Chemical processing, mining, food and beverage, plastics, and other industries utilize the switches, thanks to their customizable designs and consistent performance. An advantage offered by vibrating fork level switches is a resistance to factors that sometimes confound other technologies employed for level indication. The devices will reliably function despite flow, bubbles, foam, vibration, and coating complexities related to the subject liquids. Additionally, vibrating fork switches are reliable in both high level and low level indication scenarios.

Highly viscous liquids are generally not good candidates for the application of a vibrating fork level switch. Some liquids present the potential for material accumulation between the forks, possibly resulting in poor performance. Both of these limitations are addressed by various design features incorporated by different manufacturers.

The SIEMENS SITRANS LVS200 is a vibrating point level switch for high or low levels of bulk solids. The standard LVS200 detects high, low or demand levels of dry bulk solids in bins, silos or hoppers. The liquid/solid interface version can also detect settled solids within liquids or solids within confined spaces such as feed pipes. It is designed to ignore liquids in order to detect the interface between a solid and a liquid. Additionally, the SITRANS LVS200 has an optional 4 to 20 mA output for monitoring buildup on the fork to determine when preventative maintenance should be performed in sticky applications.

For more information on any level sensing application, contact Ives Equipment by visiting http://www.ivesequipment.com of calling 877-768-1600.

The Ten Things Everyone Should Know about pH and ORP

Reprinted with permission from AquaMetrix Instruments

Here is a list of the ten things anyone in the business of measuring the pH or ORP of their process should know that will make his or her job more stress-free.

1. pH measurements are only good to 0.1 pH units.

Electrodes are funny things. They are the only electronic components that don’t even have specifications listed in their data sheets. One major figure of merit, the impedance of the glass electrode, is on the order of megaohms and can vary by a factor of two. Cross sensitivity to other ions (e.g. sodium), response time and differences between any two electrodes limit the accuracy of measurement. Expecting ac- curacy of greater than 0.1 pH units is

2. Speaking of accuracy... It is not the same as precision.

For a consistent process a pH probe can achieve precision of results to within 0.02 units but it’s accuracy will always be limited by variables such as calibration accuracy, high sodium content or careful routine calibration, however, will narrow the gap between the accuracy of readings closer to the lower level of precision.

3. ORP measurements are only good to ± 20 mV.

Once again the measurement of ORP might be characterized by a high precision but the accuracy of the reading is constrained by the dif culty of calibration, as explained in point 6, and the non-buffered calibration solutions that allow the ORP value of the calibration solutions to change over time. Whereas the buffered composition of pH calibration solutions insures that they will change minimally an ORP calibrations solution is a mixture of Fe2+ and Fe3+ salts. Just the addition of air to the mixture will increase the ORP of the mixture. So don’t look for “NIST traceable” on the label of an ORP calibration solution.

4. ORP measurements are relative.

The process electrode is nothing more than a platinum (or gold) band upon which oxidation (reduction) reactions take place. To complete the circuit, as in all potentiometric devices, is a
reference electrode. Usually that is the same Ag/AgCl electrode used in a pH probe so the REDOX potential that you read is the difference between the Pt band process electrode and the arbitrarily chosen reference electrode. What matters most with an ORP measurement is its change to an agreed upon standard.

5. pH calibration requires two points.

Calibration measures the response of an instrument as one changes the measurement variable in a known way. For pH measurements that measurement variable is the concentration of hydrogen ions. One calibrates a pH probe by drawing a line through points representing the response of a pH probe to more than one H+ ion concentrations (or pH values). Therefore calibration requires at least two points.

6. ORP calibration can only realistically be done with one point.

This sounds like a reversal of point 4 but it’s not. ORP is not a measure of any one species (e.g. H+ ions or oxygen molecules). It measures the collective REDOX potential of everything in the water. Furthermore calibration solutions, e.g. 200 mV Light’s solution and 600 mV Zobell’s solution are two completely different mixtures of reagents. Therefore all we can is choose one calibration solution and calibrate for it.

7. ORP measurements can be slow.

Stick an ORP probe in a calibration solution and you will get a steady reading with- in half a minute. Take the same probe and stick it in a glass of tap water and it might take 20 minutes for the reading to settle to the 200-300 mV that is typical of tap water. The response of the process electrodes to the REDOX reactions that take place on the surface of a Pt electrode depends on the speed of the many reactions that give the potential and the rate at which molecules diffuse through the water. The Fe2+ and Fe 3+ ions that comprise most of the ORP value in calibration solutions react very quickly with the Pt but the Cl- and dissolved oxygen that make up tap water react much more slowly. So the key to successful ORP measurement is patience.

8. pH measurements must be temperature compensated to be accurate.

A pH measurement is the determination of H+ ions in solution. Higher temperature causes the chemical activity to increase and the pH reading to increase accordingly. So we must remove the temperature effect by measuring it and using the well known Nernst equation to correct it for the reading at 250C. (The correction is quite simple. The pH value is proportional to temperature when the latter is an absolute value (i.e. in Kelvins).

9. ORP measurements are affected by temperature but are NOT corrected for it.

An ORP value simply reflects the ability of whatever is in the water to oxidize whatever contaminants are in the water. Of course oxidation speeds up at higher temperatures. But since ORP measures the rate of chemical reactions and not any one chemical species there is no need to correct it. However we can convert the temperature reading to the ORP that we would measure at 250 C so that we have a basis for comparing the chemistry of the process. That’s why we provide a temperature sensing thermistor or RTD with our differential ORP probes.

10. A differential probe properly cared for will last a long time but it won’t last forever.

Over time chemicals in the process make their way through the junction or salt bridge and into the pH 7 buffer that bathes the reference electrode. Manufacturers go to great length to minimize this contamination but they can only slow it down. Aquametrix differential probes allow the user to cheaply and quickly replenish both the pH 7 solution and the salt bridge so that our probes our industry leaders when it comes to probe lifetime. Nonetheless electrodes themselves lose their efficiency as the glass becomes contaminated and/or eroded by the process. However the good news that, with routine calibration and maintenance an Aquametrix differential probe can last for years in most environments. As the car ads say, “your mileage will vary” but rest assured there is no probe on the market that will outlast an Aquametrix differential probe... as long as you take good care of it.

Ives Equipment Market Overview

Diaphragm Seals: Critical Isolation and Protection for Your Process Instruments

Diaphragm Seal courtesy of
AMETEK U.S. Gauge

Diaphragm seals play a critical role in protecting items like pressure switches, gauges, and transmitters from the fluid being evaluated by the sensor. The seal is a flexible membrane which both seals and isolates an enclosure. Pressure crosses the barrier without inhibition, but the material being contained does not. Typical materials composing diaphragm seals are elastomers, with rubbers being the prime substance in both general and specialty purposes.

In the operating principle of the diaphragm seal, the chamber between the diaphragm and the instrument is filled with system fluid, allowing for the transfer of pressure from the process media to the sensor being protected. The seals are attached to the process by threaded, open flange, sanitary, or other forms of connection.  The seals can also be known as ‘chemical seals’ or ‘gauge guards’. Stainless steel, Carpenter 20, Hastelloy, Monel, Inconel, and titanium are used in high pressure environments, and some materials are known to work better when paired with certain chemicals.

Diagram of diaphragm seal
(courtesy of Wikipedia)

Sanitary processes, such as food and pharmaceuticals, use diaphragm seals to prevent against the accumulation of process fluid in pressure ports. If such a buildup were to occur, such as milk invading a pressure port on a pressure gauge and spoiling, the quality and purity of the fluid in the process may be compromised. Extremely pure process fluids, like ultra-pure water, could be contaminated by the metal surface of a process sensor. Pneumatic systems rely on the elimination of even the smallest pressure fluctuations, and diaphragm seals prevent those by ensuring the separation of the process materials from the sensors.

Diaphragm seals protect the sensors
on pressure switches like this
United Electric Controls model.

Despite their protective function and reliability, there are some potential complications related to diaphragm seals. Devices are now built to address and counter many potential issues related to process monitoring involving diaphragm seals. Products seek to eliminate any and all “dead space,” allow for continuous process flow, and are self-cleaning thanks to continuous flow design. Some high pressure seals come equipped with anti-clogging features, accomplished by the elimination of internal cavities while protecting gauges. Multi-purpose seals reduce temperature influence and improve instrument performance while pinpointing and diffusing areas of high stress. These pre-emptive measures result in longer instrument life-cycles and improve performance while ensuring protection from corrosion. The seals’ ability to protect both process quality and their own vitality make them essential components of process control.

For more information on diaphragm seals, visit Ives Equipment at http://www.ivesequipment.com or call (877) 768-1600.

Introduction to Flowmeters

Magnetic flowmeters
(courtesy of Siemens)

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.

Turbine flow meter
internal view
(courtesy of Niagara)

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.

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.

Variable Area Flowmeters
(courtesy of Siemens)

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.

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.

For any flowmeter application or question, visit Ives Equipment at www.ivesequipment.com or call (877) 768-1600.

Instrumentation and Controls for the Grain Industry

Instruments and control for grain producers.

Abstracted with permission from the Siemens "For the Love of Grain" article.  View the complete document at  the bottom of this post or download it from Ives Equipment here.

A successful grain merchant during the 1840s is considering expansion in the coming years. Recent years have been fruitful, but there are rumors of a new invention on the market: a grain elevator. Claims are that this elevator is able to unload more than 1,000 bushels each hour! Compare this to current operations where workers carry sacks of grain on their backs from wagons to waiting ships. Our grain merchant has seen firsthand the hazards of this process – everything from suffocating and explosive grain dust to the daily stresses on workers’ bodies. Will this new technology be able to increase the merchant’s profits as well as make a safer working environment for employees?

Over a century and a half later, mechanized equipment is now an essential part of the grain industry, from planting and growing to harvesting, handling, and milling grain. Your challenges are still the same as those of nineteenth century grain operators, though – how can you improve processes and cut costs while also increasing safety?

Promoting a culture of safety

Working with grain has the potential to be deadly, especially when grain is in motion. Similar to ‘quicksand,’ moving grain can bury a worker in seconds. In 2010, U.S. grain operators reported that fifty-one workers had been trapped in grain, more than in any year since Purdue University began collecting data on grain entrapments in 1978. Sadly, almost half of these entrapments led to fatalities.

Increasing automation

To prevent deadly occurrences such as these, the grain industry is increasingly taking steps to reduce grain handling and storage hazards. Improving efficiency in grain facilities through automation is becoming a growing industry trend. A concern for safety is one driver behind automating operations, as a reduction in human interactions with grain decreases the occurrence of accidents.

Another reason for the push towards automation is that owners are constantly looking to increase production and reduce expenses while still producing a high quality product. A solution is to invest in automated processes in a facility. Many facilities have moved to complete automation of production, termed Totally Integrated Automation (TIA).

Refining inventory management 

Tracking inventory in grain silos is a significant component of a successful grain operation. Managing raw materials and finished products is essential for keeping processes efficient and optimizing inventory ordering and shipments. By knowing where materials are located, companies can use these resources more effectively, decreasing human intervention and increasing efficiency. As well, checking bin levels on a regular basis requires substantial labor costs. To make inventory track-ing faster and more streamlined, the industry is continually moving towards automated inventory management.

Read complete article below:

Instrumentation, Automation and Control Solutions for the Grain Industry from Ives Equipment

New Ives Equipment Video

Ives Equipment, founded in 1954, provides a diverse range of process control equipment, including valves, regulators, wireless products, flow products, pressure gauges, control products, level instrumentation, sanitary products, temperature instruments, analytical products, electric heat trace and bio-pharmaceutical products.

For more than 60 years, Ives Equipment Corporation has successfully served the industries of eastern and central Pennsylvania, Delaware, Maryland, metro NY, New Jersey, Virginia and Washington DC with the latest in process control equipment and services.

The Ives business is built on a foundation of quality people, highly trained and experienced, who take a keen interest in finding the optimum solutions to customers' control problems.