Wednesday, September 20, 2017

Trunnion vs. Floating Ball Valves

trunnion mount ball valve for industrial pipeline use
Trunnion mount ball valves have upper and lower support
points for the ball.
Image courtesy International Standard Valve, Inc.
The design, construction, and function of a ball valve is generally well understood in the industrial fluid processing arena. Ball valves provide reliable quarter turn operation, compact form factor, and tight shutoff capability, making the ball valve a preferred choice for many applications. Some ball valves also provide shutoff of fluid flow in either direction. A primary valve trim design feature permits grouping of the many variants of industrial ball valves into two categories, distinguished solely by the way in which the ball is mounted in the body.

Floating ball valves use the seats and body to hold the ball in place within the fluid flow path, with the force of directional flow pushing the ball against the downstream seats to produce a tight shutoff seal. Many floating ball valves are capable of flow shutoff in either direction. The ball is rotated by a shaft connected at the top which extends through the pressure enclosure of the valve for connection to a handle or automated actuator. The floating nature of the ball limits the applicability of this design to smaller valve sizes and lower pressures. A some point, the fluid pressure exerted on the ball surface can exceed the ability of the seats to hold the ball effectively in place.

Trunnion mount ball valves employ the stem shaft and, you guessed it, a trunnion to rigidly position the ball within the body. The shaft and trunnion, connected to the top and bottom of the ball, establish a vertical axis of rotation for the ball and prevent it from shifting in response to flow pressure. The trunnion is a pin that protrudes from the bottom side of the ball. It sits within a bearing shape, generally cylindrical, in the base of the body.

Because of their structural design, trunnion mount ball valves are suitable for all pressure ranges and sizes.They are used by many manufacturers as a basis of design for their severe service ball valve offerings. A trunnion mount ball valve can also be advantageous for applications employing valve automation. Since the ball is not held in place by a tight fitting seal arrangement, operating torque tends to be lower for comparably sized trunnion mount valves, when compared to floating ball valves.

On page 3 of the brochure included below, the exploded view of a trunnion ball valve shows the location of the trunnion assembly.

Whatever your valve application challenge, share it with an industrial valve expert. Leverage your own process knowledge and experience with their product application expertise to develop an effective solution.


Thursday, September 14, 2017

Pressure Measurement Using Isolation Ring



The D81 Isolation Ring from Winters Instrument provides a solution for measuring system pressure in processes involving fluids with potential to clog or damage sensors and impulse lines. The isolation ring has a hollow elastomer that is located between two flanges. A fitting on the elastomer section allows for connection of a gauge or transmitter without disturbing the process fluid. Pressure in the piping system is mirrored by pressure within the hollow portion of the isolation ring, measured by the connected instrument. The instrument does not come in contact with the process fluid, nor are there any small diameter impulse lines to foul or clog. Applications in mining, water treatment, pulp and paper abound. Any challenging fluid is a good candidate for application consideration. Models are available up to 48" line size, with wafer, flanged, or threaded connections.

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



Wednesday, August 23, 2017

Cooling Towers: Operating Principles and Systems

evaporative cooling tower made of HDPE plastic
Example of evaporative cooling tower, fabricated
from HDPE plastic to resist corrosion.
Image courtesy Delta Cooling Towers
The huge, perfectly shaped cylindrical towers stand tall amidst a landscape, with vapor billowing from their spherical, open tops into the blue sky. Such an image usually provokes a thought related to nuclear power or a mysterious energy inaccessible to the millions of people who drive by power plants every day. In reality, cooling towers – whether the hyperboloid structures most often associated with the aforementioned nuclear power plants or their less elegantly shaped cousins – are essential, process oriented tools that serve as the final step in removing heat from a process or facility. The cooling towers at power plants serve as both an adjuster of a control variable essential to the process and also as a fascinating component of the process behind power creation. The importance and applicability of cooling towers is extensive, making them fundamentally useful for industrial operations in power generation, oil refining, petrochemical plants, commercial/industrial HVAC, and process cooling.

In principle, an evaporative cooling tower involves the movement of a fluid, usually water with some added chemicals, through a series of parts or sections to eventually result in the reduction of its heat content and temperature. Liquid heated by the process operation is pumped through pipes to reach the tower, and then gets sprayed through nozzles or other distribution means onto the ‘fill’ of the tower, reducing the velocity of the liquid to increase the fluid dwell time in the fill area. The fill area is designed to maximize the liquid surface area, increasing contact between water and air. Electric motor driven fans force air into the tower and across the fill area. As air passes across the liquid surface, a portion of the water evaporates, transferring heat from the water to the air and reducing in the water temperature. The cooled water is then collected and pumped back to the process-related equipment allowing for the cycle to repeat. The process and associated dispersion of heat allows for the cooling tower to be classified as a heat rejection device, transferring waste heat from the process or operation to the atmosphere.

Evaporative cooling towers rely on outdoor air conditions being such that evaporation will occur at a rate sufficient to transfer the excess heat contained in the water solution. Analysis of the range of outdoor air conditions at the installation site is necessary to assure proper operation of the cooling tower throughout the year. Evaporative cooling towers are of an open loop design, with the fluid exposed to air.

A closed loop cooling tower, sometimes referred to as a fluid cooler, does not directly expose the heat transfer fluid to the air. The heat exchanger can take many forms, but a finned coil is common. A closed loop system will generally be less efficient that an open loop design because only sensible heat is recovered from the fluid in the closed loop system. A closed loop fluid cooler can be advantageous for smaller heat loads, or in facilities without sufficient technical staff to monitor or maintain operation of an evaporative cooling tower.

Thanks to their range of applications, cooling towers vary in size from the monolithic structures utilized by power plants to small rooftop units. Removing the heat from the water used in cooling systems allows for the recycling of the heat transfer fluid back to the process or equipment that is generating heat. This cycle of heat transfer enables heat generating processes to remain stable and secure. The cooling provided by an evaporative tower allows for the amount of supply water to be vastly lower than the amount which would be otherwise needed. No matter whether the cooling tower is small or large, the components of the tower must function as an integrated system to ensure both adequate performance and longevity. Understanding elements which drive performance - variable flow capability, potential HVAC ‘free cooling’, the splash type fill versus film type fill, drift eliminators, nozzles, fans, and driveshaft characteristics - is essential to the success of the cooling tower and its use in both industrial and commercial settings.

Design or selection of an evaporative cooling tower is an involved process, requiring examination and analysis of many facets. Share your heat transfer requirements and challenges with cooling tower specialists, combining your own facilities and process knowledge and experience with their application expertise to develop an effective solution.`

Friday, August 18, 2017

Thermodynamic Steam Traps

cutaway view thermodynamic steam trap
Cutaway view of disc type thermodynamic steam trap
Image courtesy of Spirax Sarco
Condensate return is an essential operation in any closed loop steam system. Steam that has lost its latent heat will collect in the piping system as hot liquid water (condensate). This liquid needs to be separated from the steam and returned to the boiler feedwater equipment without letting steam escape in the process.

Various items of steam utilization equipment and processes will result in condensate formation at different rates. The device that collects and discharges condensate to the return portion of the system is called a steam trap. There are numerous physical principals and technologies employed throughout the range of available steam trap types. Each has application limitations and strengths making them more or less suitable for a particular installation.

A thermodynamic steam trap relies on the energy provided by the condensate to move a disc which controls the flow of the condensate into the return system. The disc is the only moving part in the device. Condensate flows through a port to a chamber on the underside of the disc, lifting the disc and directing the flow to the return system or drain. Eventually, the fluid flowing into the chamber will reach a point where some of the condensate flashes to steam. A portion of this steam flows through a channel into the space above the disc, called the control chamber. The increase in pressure in the control chamber due to the steam influx pushes downward on the disc, seating it in a closed position. The trap, with the disc seated, remains in the closed position until the flash steam in the control chamber cools and condenses. Then the disc can be opened again by the inflow of condensate.

The thermodynamic disc trap is:

  • Easy to install
  • Compact
  • Resistant to damage from freezing
The single trap can cover a wide range of system pressure, and the simple construction translates into low initial cost. Properly matching any steam trap to its application is important. Share your condensate return and steam system challenges with specialists, combining your knowledge and experience with their product application expertise to develop effective solutions.



Tuesday, August 8, 2017

Orifice Plate - Primary Flow Element

orifice plate drawing
Orifice plates are simple in appearance, but exhibit
precision machining.
Image courtesy of Fabrotech Industries
An orifice plate, at its simplest, is a plate with a machined hole in it. Carefully control the size and shape of the hole, mount the plate in a fluid flow path, measure the difference in fluid pressure between the two sides of the plate, and you have a simple flow measurement setup. The primary flow element is the differential pressure across the orifice. It is the measurement from which flow rate is inferred. The differential pressure is proportional to the square of the flow rate.

An orifice plate is often mounted in a customized holder or flange union that allows removal and inspection of the plate. A holding device also facilitates replacement of a worn orifice plate or insertion of one with a different size orifice to accommodate a change in the process. While the device appears simple, much care is applied to the design and manufacture of orifice plates. The flow data obtained using an orifice plate and differential pressure depend upon well recognized characteristics of the machined opening, plate thickness, and more. With the pressure drop characteristics of the orifice fixed and known, the measuring precision for differential pressure becomes a determining factor in the accuracy of the flow measurement.

There are standards for the dimensional precision of orifice plates that address:
  • Circularity of the bore
  • Flatness
  • Parallelism of the faces
  • Edge sharpness
  • Surface condition
Orifice plates can be effectively "reshaped" by corrosion or by material deposits that may accumulate from the measured fluid. Any distortion of the plate surface or opening has the potential to induce measurable error. This being the case, flow measurement using an orifice plate is best applied with clean fluids.

Certain aspects of the mounting of the orifice plate may also have an impact on its adherence to the calibrated data for the device. Upstream and downstream pipe sections, concentric location of the orifice in the pipe, and location of the pressure measurement taps must be considered.

Properly done, an orifice plate and differential pressure flow measurement setup provides accurate and stable performance. Share your flow measurement challenges of all types with a specialist, combining your own process knowledge and experience with their product application expertise to develop an effective solution.

Thursday, August 3, 2017

Thermocompressor Breathes New Life into Low Pressure Waste Steam

steam thermocompressor
Steam Jet Thermocompressor from Spirax Sarco
mixes high pressure and low pressure steam supplies
Energy conservation and energy efficiency have contributed very large cost savings to many industrial and commercial operations over the past two decades. Projects with modest payback periods quickly begin their contributions directly to the bottom line of the balance sheet. In many instances, incorporating energy conservation and efficiency measures also improves the overall functioning of the consuming systems and equipment. In order to save energy, it is generally necessary to exercise better control over equipment or system operation by gathering more information about the current operating state. This additional information, gathered through measurement instrumentation, often finds use in other ways that improve productivity and performance.

Steam is utilized throughout many industries as a means of transferring heat, as well as a motive force. Much energy is consumed in the production of steam, so incorporating ways of recovering or utilizing the heat energy remaining in waste steam is a positive step in conservation.

A thermocompressor is a type of ejector that mixes high pressure steam with a lower pressure steam flow, creating a usable discharge steam source and conserving the latent heat remaining in the low pressure steam. The device is compact and simple, with no moving parts or special maintenance
thermocompressor labelled schematic
Schematic of basic thermocompressor, showing suction
inlet at the bottom and high pressure steam nozzle.
Image courtesy of Spirax Sarco
requirements. Two general varieties are available. The fixed nozzle style is intended for applications with minimal variation in the supply and condition of the suction steam (the low pressure steam). Some control is achievable through the regulation of the high pressure steam flow with an external control valve. A second style provides a means of regulating the cross sectional area through which the high pressure steam flows in the nozzle. This style is best applied when specific discharge flow or pressure is required, or there is significant variation in the inlet steam conditions.

Share all your steam system challenges with a steam system application specialist. Combine your own process and facilities knowledge and experience with their product application expertise to develop effective solutions.


Thursday, July 27, 2017

Valve Positioners

industrial valve actuator with positioner
Valve positioner installed on pneumatic actuator
Courtesy Crane ChemPharma Energy
Valve positioners can provide process operators with a precise degree of valve position control across the valve movement range, as well as information about valve position. A relationship exists between applied pneumatic signal pressure and the position of the valve trim. The relationship between the two elements is dependent upon the valve actuator and the force of the return spring reacting to the signal pressure. In a perfect world, the spring and pneumatic forces would reach equilibrium and the valve would return to the same position in response to an applied signal pressure. There are other forces, however, which can act upon the mechanism, meaning the expected relationship between the original two elements of pressure and position may be offset. For example, the packing of the valve stem may result in friction, or the reactive force from a valve plug resulting from differential pressure across the area of the plug may be another.

While these elements may seem minor, and in some cases they are, process control is about reducing error and delivering a desired or planned output. Inclusion of a positioner in the valve assembly can ensure that the valve will be set in accordance with the controller commands.

Each positioner functions as a self-contained small scale control system. The first variable in the positioning process is the current valve position, read by a pickup device incorporated in the positioner. A signal which is sent to the positioner from the control system, indicating the desired degree of opening, is used as the setpoint. The controller section of the positioner compares the current valve position to the setpoint and generates a signal to the valve actuator as the output of the positioning process. The process controller delivers a signal to the valve, and then the positioner takes that signal and supplies air pressure required to accomplish the needed adjustment of the stem position. The job of the valve positioner is to provide compensatory force and to act as a counterbalance against any other variables which may impact valve stem position.

Magnetic sensors can be employed to determine the position of the valve stem. The magnetic sensor works by reading the position of a magnet attached to the stem of the valve. Other technologies can be employed, and all have differing ways of overcoming degrees of inaccuracy which may arise with wear, interference, and backlash. In addition to functioning as a positioner, control valve positioning devices can also function as volume boosters, meaning they can source and subsequently ventilate high air flow rates from sources other than their pneumatic input signal (setpoint). These devices can positively affect and correct positioning and velocity of the valve stem, resulting in faster performance than a valve actuator solely reliant on a transducer.

The inclusion of a positioner in a control valve assembly can provide extended performance and functionality that deliver predictable accurate valve and process operation. Share your valve automation requirements with a knowledgeable specialist and combine your process knowledge and experience with their product application expertise to develop an effective solution.

Friday, July 21, 2017

Pressure Motive Condensate Pumps



In a closed steam system, condensate must be returned to the feedwater side of the boiler. Moving this condensate effectively through the system is essential to maintaining design performance levels throughout the system. Condensate can be considered "spent steam", but still retains great value as preheated and treated feedwater for the boiler.

Three general methods are employed to transport condensate from where it is collected to where it is reused. If the facility layout permits, gravity can be the motive force to move the condensate back to the boiler. A second option is a mechanical pump, unsurprisingly called a condensate pump. The third common option is to employ system steam pressure to drive the condensate through the return piping and back to the boiler.

The concept of gravity return for the condensate is easy to envision....liquid flows downhill. Mechanical pumps, as well, are a well understood means of moving liquids. When the condensate collector reaches a certain fill level, the pump is energized and the liquid is forced through the return piping.

Using pressure as the motive force for condensate return involves coordinated operation of inlet, outlet, and vent openings to the condensate collection vessel. A float inside the collection vessel and a connected mechanism provide control of the valves at the vessel openings. In the video, you can see how the valve operating sequence provides for periods of condensate collection, then condensate discharge.

Share all of your steam system challenges with application specialists, combining your own process and facilities knowledge and experience with their product application expertise to develop effective solutions.

Wednesday, July 19, 2017

Integrated Solution for Chilled Water Coil Control

integrated sensors, controller, control valve, actuator for HVAC
Monitrol includes controller, sensors, control valve, and
actuator in a single integrated package.
Image courtesy of Warren Controls
The final control element used for heating or cooling via a heat transfer fluid is going to be a control valve, most often one capable of modulating the fluid flow by precise valve positioning. This control activity requires sensors, the control valve, a controller, and an actuator.

Selecting, installing, and coordinating the operation of these components can be challenging and time consuming, especially when the components are sourced from varied manufacturers. Warren Controls delivers a consolidated solution with their Monitrol line of control valves intended for heat transfer control tasks and related operations. The Monitrol concept involves combining pre-engineered and matched controllers and actuators with flow control valves equipped with built-in sensors for pressure, temperature, or flow. Measurement and control is performed locally, with communications between the local and central controllers exchanging setpoint and performance information. The solution is compact and simplified, enabling easy selection, installation, and startup.

More details are provided in the document included below. There are numerous product variants to accommodate a wide array of field applications. Share your fluid control and heat transfer requirements and challenges with an application expert, combining your own facility and process knowledge with their product application expertise to develop an effective solution.


Thursday, July 6, 2017

Added Safety For Pneumatic Actuators

pneumatic actuator for industrial process control valve
XL Series Pneumatic Actuator
Courtesy Emerson - Hytork
Manufacturers of industrial process control gear keep the safety of their customers as a high priority item when designing products. There is much at stake in industrial operations, so every instance where the probability or impact of failure can be reduced is beneficial.

Pneumatic valve actuators utilize pressurized air or gas as the motive force to position a valve. A common version of these air powered actuators employs a rack and pinion gear set that converts the linear movement of air or spring driven pistons to rotational movement on the valve shaft. When one side of the piston is pressurized, the pinion bearing turns in one direction. When the air or gas from the pressurized side is vented, a spring (spring-return actuators) may be used to rotate the pinion gear in the opposite direction. A “double acting” actuator does not use springs, instead using the pneumatic supply on the opposing side of the piston to turn the pinion gear in the opposite direction.

From time to time, service or maintenance operations for the actuator may require opening of the pressure containing case. This is a potentially hazardous step and confirmation that the case is not pressurized when disassembly is undertaken is essential to a safe procedure. Many pneumatic actuators have cases assembled with numerous threaded fasteners. Hytork, an Emerson brand, employs a keyway and flexible stainless steel key to affix the end caps to their XL Series pneumatic actuators. This method provides a number of benefits, not the least of which is preventing the removal of the key and end cap if the case is pressurized.

Find out more about the XL Pneumatic Actuators in the illustrated piece provided below. Share your industrial fluid control challenges with industrial valve and automation specialists, combining your own process experience and knowledge with their product application expertise to develop effective solutions.


Thursday, June 29, 2017

Sterling Condensate Return and Steam Control Equipment



Sterling, under the Sterlco brand, manufactures a range of Steam control products for commercial and industrial use. Steam traps, condensate return pumps, boiler feed pumps, and self regulating temperature control valves are all part of the product offering. The video included with this posting provides a short overview of the product extent of the Sterlco line.

Share your steam system challenges with product application specialists. Combine your own facilities and process knowledge and experience with their product application expertise to develop the  most effective solutions.

Tuesday, June 20, 2017

Shell and Tube Heat Exchangers

large shell and tube heat exchangers at oil refinery
These shell and tube heat exchangers are at an oil refinery, but
their application crosses all industry boundaries.
Cars are something which exist as part of the backbone of modern society, for both personal and professional use. Automobiles, while being everyday objects, also contain systems which need to be constantly maintained and in-sequence to ensure the safety of both the machine and the driver. One of the most essential elements of car ownership is the understanding of how heat and temperature can impact a car’s operation. Likewise, regulating temperature in industrial operations, which is akin to controlling heat, is a key process control variable relating to both product excellence and operator safety. Since temperature is a fundamental aspect of both industrial and consumer life, heat management must be accurate, consistent, and predictable.

A common design of heat exchangers used in the oil refining and chemical processing industries is the shell and tube heat exchanger. A pressure vessel, the shell, contains a bundle of tubes. One fluid flows within the tubes while another floods the shell and contacts the outer tube surface. Heat energy conducts through the tube wall from the warmer to the cooler substance, completing the transfer of heat between the two distinct substances. These fluids can either be liquids or gases. If a large heat transfer area is utilized, consisting of greater tube surface area, many tubes or circuits of tubes can be used concurrently in order to maximize the transfer of heat. There are many considerations to take into account in regards to the design of shell and tube heat exchangers, such as tube diameter, circuiting of the tubes, tube wall thickness, shell and tube operating pressure requirements, and more. In parallel fashion to a process control system, every decision made in reference to designing and practically applying the correct heat exchanger depends on the factors present in both the materials being regulated and the industrial purpose for which the exchanger is going to be used.

The industrial and commercial applications of shell and tube heat exchangers are vast, ranging from small to very large capacities. They can serve as condensers, evaporators, heaters, or coolers. You will find them throughout almost every industry, and as a part of many large HVAC systems. Shell and tube heat exchangers, specifically, find applicability in many sub-industries related to food and beverage: brewery processes, juice, sauce, soup, syrup, oils, sugar, and others. Pure steam for WFI production is an application where special materials, like stainless steel, are employed for shell and tube units that transfer heat while maintaining isolation and purity of a highly controlled process fluid.

Shell and tube heat exchangers are rugged, efficient, and require little attention other than periodic inspection. Proper unit specification, selection, and installation contribute to longevity and solid performance. Share your project challenges with application experts, combining your own process and facilities knowledge with their product application expertise to develop effective solutions.

Thursday, June 15, 2017

Natural Gas Fueling Station Process Filter and Dryer

natural gas vehicle fueling station dryer with stationary regenerator
Single tower natural gas dryer with stationary regeneration system
used for removing water vapor and particulate contaminants from
vehicle fuel.
Courtesy SPX Flow - Pneumatic Products
Natural gas fueled vehicles now occupy a formidable niche in the transportation market. With low cost, low emission operation, natural gas vehicles continue to expand their presence in fleets around the world.

Commercially available engines of almost all types operate best and longest when powered with clean fuel that is free of particulates and other contaminants that increase wear on internal and moving parts. Water vapor also has some deleterious effects on many components and should be kept at very low levels.

Fuel can change custody and container numerous times during transport from production to consumption point. Opportunities for contamination exist along the supply chain, making a final processing of the fuel immediately prior to its dispensing to a vehicle a positive and beneficial operation.

SPX Flow, under the Pneumatic Products brand, manufactures single and twin tower desiccant dryers designed to remove water vapor from natural gas. The skid mounted units also include particulate and coalescing filters that capture solid contaminants to a submicron level.

Specifically engineered for large flow heavy-duty natural gas vehicle fleet refueling applications, units are available for intermittent, low, moderate, and heavy demand operations. Single tower units are economical for low to moderate levels of use. Twin tower systems, with self-contained regeneration, provide continuous operation and delivery of dried compressed natural gas (CNG) for fueling operations.

Single tower dryers can be provided with a stationary desiccant regeneration system on board. This enhances convenience by eliminating the need for a third party regeneration service. The desiccant is processed in place, without replacement. Single tower dryers are suitable for low to moderate volume application.

Single tower units, without a stationary regeneration system, are suitable for intermittent or low volume use. A mobile regeneration unit can provide self directed processing of the desiccant media in place, eliminating the need for disposal and replacement. Alternatively, third party service providers can come to the site and replace or regenerate the desiccant.

Twin tower purification systems are completely self-contained, fully automatic, heat-reactivated, closed-loop blower purge units capable of continuous operation for facilities with high flow requirements or uninterrupted 24 hour operation.

More detail is provided in the datasheet below. Share your natural gas vehicle fueling station challenges with a product application specialist for help in determining the most suitable equipment for your application.


Wednesday, June 7, 2017

Metal Diaphragm Valves - Best Applications

pneumatically operated diaphragm valve industrial valve
Diaphragm valve, pneumatically actuated
Courtesy GEMU
There are more valve selection options available than one can count. Differing types, sizes, materials, and other special characteristics distinguish each and every product as unique in its own way. Matching the design and performance strengths of a particular valve to the requirements of an application may require some investment in time and research, but the payback can be years of trouble free performance.

Diaphragm valves are beneficial for applications requiring hermetic isolation of the valve bonnet and stem from the media. The diaphragm serves as the isolating barrier. The valves are generally tolerant of particulate matter entrained in the media, and provide good shutoff and throttling capability. Body and diaphragm materials should be selected that are compatible with the media.

Body styles are either weir or straight through design. Straight through body styles offer a less restricted flow path than the weir type, but diaphragm movement in the weir style is reduced. Diaphragms do wear and will need to be replaced at some point. Valves should be installed with good service access.

There are many variants of diaphragm valves, broadening their suitability for a wide range of industrial applications. Share your fluid process control challenges with application specialists, combining your process knowledge with their product expertise to develop effective solutions.

internal diagram of weir type diaphragm valve
Weir body style diaphragm valve
Coutesy GEMU

Friday, June 2, 2017

Self Contained Temperature Regulators

pilot operated temperature regulator valve
Pilot operated temperature regulator
Courtesy Spirax Sarco
Not everything in process control is complicated. Some requirements can be fulfilled by proper application of the right product.

Temperature control, the regulation of heat content, transfer of heat, or whatever else it may be called, is an ubiquitous operation in industrial, commercial, and institutional settings. The range of complexity or challenge in temperature control applications extends from very simple to almost blindingly complex. The key to finding the right solution for any of these applications lies in understanding how the process works, setting an appropriate measurement method for the process condition, establishing a control method or algorithm that adequately responds to the process, and integrating an output device capable of delivering heat or cooling in accordance with the controller commands.

Somewhere along the continuum of project complexity is a zone that is well served by simple and rugged devices that incorporate temperature measurement and control into a single device. Self contained temperature regulators are pilot or direct operated units comprised of a filled bulb temperature sensor that operates a modulating valve that controls the flow of liquid or steam used to regulate the process temperature. The regulators offer a host of advantages.

  • No external power source required for operation
  • One device to specify, purchase, and install
  • Installed by a single trade
  • Low, almost no, maintenance
  • Intrinsically safe operation
The document provided below illustrates several variants, along with application examples and principal of operation. Not every application needs a microprocessor controller. Share your temperature control applications and challenges with process control specialists, combining your own process knowledge and experience with their product application expertise to develop an effective solution.



Monday, May 22, 2017

Introduction to Valve Parts or Components

cutaway view forged steel gate valve
Cutaway view of a forged steel gate valve
Courtesy Crane-ChemPharmaEnergy
Although there are many different classifications of valves specific to their respective functions, there are standard parts or components of valves you may find regardless of the classification. They are the valve body, bonnet, trim, seat, stem, actuator, and packing.

The Valve Body is the primary boundary of a pressure valve which serves as the framework for the entire valve’s assembly. The body resists fluid pressure loads from connected inlet and outlet piping; the piping is connected through threaded, bolted, or welded joints.

The Valve Bonnet is the opening of the Valve Body’s cover. Bonnets can vary in design and model, is built using the same material as the Valve Body, and is also connected to the entire assembly through threaded, bolted, or welded joints.

The Valve Trim collectively refers to all the replaceable parts in a valve, e.g. the disk, seat, stem, and sleeves––all which guide the stem as well.

The Valve Disk allows the passage or stoppage of flow. Disks provide reliable wear properties and differ in what they look like per valve type. For example, in the case of a ball valve, the disk is called a ball, whereas for a plug valve it is a plug.

The Valve Seat(s) or it’s seal rings provide surface seating for the disk. For example, a globe valve requires only one seat and this seat forms a seal with the disk to stop flow.

The Valve Stem provides the proper position which will allow the opening and closing movement of the Valve Disk. Therefore, it is connected to the Valve Disk on one end and the Valve Hand Wheel or the Valve Actuator on the other.

The Valve Yoke is the final piece in the valve’s assembly; the Yoke connects the Valve Bonnet with the actuating mechanism. The Valve Stem passes through the top of the Yoke which holds the Yoke or stem nut.

There are countless variants of valve designs, sizes, and configurations. These basic parts will be found on most, but the particular form and arrangement of the part may provide an advantage when employed for a particular application. Share your industrial process valve requirements and challenges with a valve specialist. Combine your own process knowledge and experience with their product application expertise to develop an effective solution.

Monday, May 15, 2017

Wireless Communications in Industrial Process Control

symbolic wireless communications or transmission tower antenna
Industrial wireless communications for process control
Electrical cables, for many years, were the only option for connecting measurement devices with their companion control and monitoring gear. While wired connections are still in widespread use, probably still the predominant connection method, wireless communication technology offers a range of advantages in connecting process measurement instruments and their controls.

Bandwidth, in wireless communication and modem data transmission terminology, is the analog range of the radio spectrum’s frequencies, or wavelengths, used to transmit a signal between transmitter and receiver. Jurisdictional agencies throughout the world regulate the use of bandwidth and assign ranges for use by public and private organizations.

Before there can be an appreciation of radio transmissions, there first must be an understanding on the transmission medium. Radio transmissions run on the UHF radio spectrum, or the Ultra high frequency spectrum, named by the International Telecommunication Union; the spectrum runs from 300 megahertz (MHz) to 3 gigahertz (GHz).

There are two prominent frequencies utilized for industrial wireless communications in the US: 900 MHz and 2.4 GHz. Within the allocated bandwidth, there are numerous individual channels that can be used for applications.

Each of the available bandwidths has its own transmission characteristics which may make it advantageous for a particular application. Amateur radio stations operate in the 900 MHz range because attenuation of the transmission signal is less than at higher frequencies. Higher frequencies have greater theoretical transmission range, but can be impaired by smaller sized objects in the transmission path because of their shorter wavelength.

Due to a number of practical application factors, 2.4 GHz technology is predominate in consumer and many industrial applications; one of the main reasons is the sheer amount of concurrent signals in the designated bandwidth. The 2.4 GHz band can accommodate more concurrent users or devices. Both frequency ranges have useful application in automation and process control, enabling effective connections between devices over distances from several feet to thousands of miles.

Thursday, May 11, 2017

Rack and Pinion Actuator - Double Acting vs. Single Acting

pneumatic valve actuator
Pneumatic rack and pinion valve actuator
Courtesy Emerson - Hytork
Automating industrial valve operation requires numerous considerations in selecting the correct power source, drive type, torque range, and much more. The widest range of possible operation conditions should be anticipated and accommodated by the actuator selection to assure safe and effective valve operation under normal and adverse conditions.

The use of compressed air or gas as the energy source for valve positioning has been in use for many years and remains popular to this day. Among the perceived advantages of this energy source are the ability to store it in pressurized vessels for emergency short term use and the absence of any potential ignition source, as may be the case with electric powered actuators.

A rack and pinion valve actuator delivers a linear torque output throughout its full range of travel. The movement of a piston causes movement of the rack. The rack is toothed, and drives the pinion, converting linear movement of the rack into rotational movement of the pinion. The pinion is connected to the valve shaft, providing re-positioning of the valve. Adjustable stops, part of the actuator, limit the travel of the valve trim.

spring return and double acting valve actuator diagrams
Double acting pneumatic rack and pinion actuator (left) on its inward stroke. Spring return actuator (right) on its
outward or air powered stroke  (Illustrations courtesy of Emerson - Hytork) 

There are two common configurations of rack and pneumatic pinion actuators. A double acting actuator has provisions for delivering or exhausting air from both sides of the piston. Small control valves coordinate the delivery and removal of pressurized air or gas to drive the pistons inward or outward, producing torque in a clockwise or counterclockwise direction. Its operation could also be described as "air to open, air to close".

The single acting version of the pneumatic rack and pinion actuator provides air driven movement in only one direction. In this case, reversing the direction of travel is accomplished with a spring installed within the chamber on one side of the pistons. The spring powered movement provides a fail safe positioning of the valve in the case of control air pressure loss. This actuator provides "air to open, spring to close" operation, although, in some cases the fail safe position can be changed.

This is the simple version. Share your process control challenges with a valve expert, combining your own process knowledge and experience with their product application expertise to develop effective solutions.



Tuesday, May 2, 2017

Steam Traps

high pressure float type steam trap cutaway view
Cutaway view of high pressure float type steam trap
Courtesy Spirax Sarco
Steam is widely used throughout industrial, commercial, and institutional facilities and a means of transferring heat energy, as well as a wide array of other applications. Steam generation cost is a substantial line item on almost any balance sheet, so deriving the most efficient level of operation from a steam system pays tangible dividends.

Utilizing the heat content of steam, in a closed system, results in the production of condensate. Condensate is hot liquid water which can be returned to the boiler and re-vaporized. Managing the separation of the liquid condensate from the process steam and sending it to the lower pressure condensate return line is the function of a steam trap. A steam trap filters out condensate (condensed steam) via an automatic valve. The trap also removes air without letting process steam escape. By filtering out the condensate and not the steam, steam waste is minimized. Steam traps generally are self-contained automatic devices. Since steam based heating processes generally rely on latent heat transfer for rapid and efficient operation, it is necessary to continually collect and transfer condensate from the steam containing portion of the system. The condensate will reduce heat exchanger performance if allowed to accumulate.

Historically, there have been three main types of steam traps: mechanical traps, thermostatic traps, and thermodynamic traps. Most commonly used mechanisms rely on differences in temperature, specific gravity, and pressure. The mechanical trap was originally developed as a bucket trap, which was a rather large trap where a bucket floated up or down to open and close a valve. Bucket traps with a lever, which face downward – also known as ‘closed bucket’ traps – are still used today as a float type trap. Processes requiring large capacities for discharge still currently use the bucket type or float type trap, with long services lives. In the modern version of a free float trap, the condensate is continuously discharged while the valve opening is constantly controlled by the amount of buoyant force acting upon a tightly sealed float.

Thermostatic traps are a smaller, more compact design. Using a temperature sensing mechanism, and operable by mechanisms like bellows or bimetal rings, these thermostatic traps have a slower response. Processes relying on rapid condensate discharge most likely will not use thermostatic traps. An example of a trap used in the process industry today is a bimetal temperature control trap. The trap includes steam tracers and will discharge when a certain condensate temperature is reached.

The core limitation of thermostatic steam traps – the slow response time – has been addressed via the development of the thermodynamic steam trap. The thermodynamic trap operates on the expansion and contraction of an encapsulated liquid. This version of steam trap allows for the smallest amount of condensate accumulation. Early models resulted in unacceptable levels of steam loss. As a result, the commonly used disc type trap was developed for mainstream use. The disc type is compact, versatile, and relatively affordable in terms of installation costs. In the modern disc type, pressure fluctuations in the chamber above the valve result in the valve’s opening and closing. Though in use for many years, development and refinement continues on steam traps, bringing ever better performance to this ubiquitous steam specialty.

Share your challenges with a steam system specialist, combining your own process and facilities knowledge and experience with their product application expertise to develop effective solutions.

Saturday, April 29, 2017

Dual Application for Cooling Tower

Plastic cooling tower air stripper
Plastic cooling tower assembly
Courtesy Delta Cooling Towers
Cooling towers are readily identified by their ubiquitous presence in large commercial cooling systems. They are an effective means of rejecting heat from from a centralized liquid system. The general operating principle of a cooling tower involves a thermal and mass transfer from the cooling water to the surrounding air. The water is distributed by a number of means throughout the cooling tower fill, drastically expanding the surface area of the water. Air from the surrounding atmosphere is moved across the water surface. Assuming that the air is within the performance range of the cooling tower, the resulting evaporation of a portion of the water cools the liquid water remaining behind.

There are other applications for cooling towers, and Delta Cooling Towers, Inc., described one in a March 2017 news post. The application centered around a municipality with two challenges in providing potable water to residents. The water was being sourced from very deep wells and, without treatment, had an unacceptably high delivery temperature. Additionally, the sourced groundwater exhibited unacceptable levels of radon and hydrogen sulfide, naturally occurring gaseous contaminants that required level reductions to render the water suitable for human consumption and use.

Air strippers, equipment that aerates the water, are a common means of reducing the gaseous contaminant levels. In this case, though, there was the additional challenge of reducing the water temperature. All needed to be accomplished at process flow rates commensurate with the size of the municipal water demand.
A solution that solved both issues arose with the use of a cooling tower selected to provide sufficient aeration for gaseous contaminant reduction and cooling of the water to acceptable levels.
You can access the entire case history by reaching out to a product specialist, with whom you should share your own liquid processing challenges. Combining your process knowledge and experience with the product application expertise of knowledgeable professionals will produce effective solutions.

Friday, April 21, 2017

Vibration Dampening Improves Pressure Gauge Reading



Bourdon tube pressure gauges can exhibit rapidly oscillating indicators when subjected to pulsations from the measured line. The fast moving pointer on the dial face makes it impossible for an observer to obtain an accurate reading from the gauge. One solution has been to fill the case with a viscous liquid that served to dampen the vibration. While this is generally effective, it does create an additional potential maintenance burden related to the liquid.

A better solution is a dry gauge with a suitable means of dampening pointer oscillations that rivals that of liquid filled gauges. Winters Instrument, a manufacturer of industrial instrumentation on a global scale, offers a range of pressure gauges with their StabilZR™ dampened movement that provides liquid filled performance in a dry gauge.

The short video included with this post compares a standard dry gauge, liquid filled, and StabilZR™ versions. You can see the performance difference. Learn more about the StabilZR™ pressure gauges by sharing your process instrumentation challenges with application experts, combining your own process knowledge and experience with their product application expertise to develop effective solutions.


Tuesday, April 11, 2017

High Visibility Process Gauges Deliver Improved Readability in Low Light Conditions



Process gauges can sometimes, by necessity, be located in areas with low lighting or other conditions that do not promote easy viewing and reading of their dial face. Winters Instruments, manufacturer of a range of industrial instrumentation including dial face gauges, has released their WinBRIGHT high visibility pressure gauge dials. The new gauge dials provide either a highly reflective background color or glow in the dark option for the company's offering of pressure gauges in the 4" through 6" diameter range.

The video provides a quick overview of the new offering. Considering these gauges for installation in existing or new processes can bring better visibility to operators and technicians reading process gauges. More information is available from instrumentation specialists, with whom you should share your process measurement challenges and requirements. Combining your own experience and process knowledge with their product application expertise will yield a positive solution.

Wednesday, April 5, 2017

Closed Loop Cooling - Alternative Setup Delivers Benefits

Industrial processing often requires the transfer of heat, sometimes into the process, sometimes out of the process. External heat sources are often steam, hot water, or electric heaters. There are also instances where processing machinery either adds heat to the process or requires heat removal (cooling) in order to maintain proper function. If the heat source can accommodate a flowing liquid to provide removal of excess heat, it is a candidate for a closed loop cooling system.

One schematic for a closed loop cooling circuit would show the heat source connected to the piping system, with a pump for circulation and a finned coil located outdoors. The pump moves the heat transfer liquid through the hot area where heat moves from the process to the flowing liquid. The heated liquid continues to flow through the piping system to the finned coil, located outdoors. A fan moves air across the coil to provide heat transfer. The finned coil size would need to be comparatively large, since only sensible cooling using the forced air is employed. The fan capacity would be commensurate with the coil size and the circulating pump rating would be in line with the fluid moving requirements of the system. While this design is fairly simple, there may be a more efficient way to accomplish the heat transfer and deliver what may be beneficial additional features.

Consider a different schematic for the same application. This alternate design employs a closed loop cooling circuit for the heat source, but utilizes a different means of rejecting the heat from the closed loop to the outside air. A plate and frame heat exchanger transfers heat from the closed cooling loop to an open loop circuit that circulates through a cooling tower located outdoors. This scenario maintains the closed loop nature of the equipment cooling circuit, preventing entry of particulates or dissolved gases into the cooling fluid circulating through the process or machinery. Here is what the schematic looks like, courtesy of Delta Cooling Towers .
closed loop cooling system schematic with cooling tower
Closed loop cooling of process heat source using plat and frame heat exchanger and induced draft cooling tower
Courtesy Delta Cooling Towers
The cooling tower offers far greater efficiency than the fan and coil arrangement in the first design. Employing a plastic cooling tower will drastically reduce the life cycle cost over a galvanized steel model and the cooling tower will occupy significantly less space and require less costly support structure than the larger fan and coil arrangement. Total horsepower requirements for the system are reduced. The closed loop will not require any chemical additions for freeze protection because it no longer extends outdoors. This system also provides an element of flexibility, with expansion of the plate and frame heat exchanger a possibility. Cooling tower capacity is also expandable and available for other uses throughout the facility.

There are more details provided in the datasheet included below. Share your heat transfer and cooling challenges with application experts and explore various options. The combination of your process knowledge and experience with their product application expertise will produce an effective solution.


Tuesday, March 21, 2017

Forged Steel Valves for the Toughest Applications

cutaway view forged steel gate valve with handle and weld socket connections
Forged Steel Gate Valve
Cutaway View
Courtesy Crane ChemPharma Energy
Forging steel produces material of greater overall strength and toughness for parts and assemblies subjected to higher levels of stress. Forging is basically accomplished by applying localized mechanical pressure across the base steel, eliminating internal voids and gas pockets, while producing a unique oriented grain structure in the metal that delivers increased fatigue resistance.

Higher pressure or temperature applications in fluid process control can benefit from, and sometimes may require, the use of forged steel valves. Their ruggedness and ability to hold up under tough conditions make forged steel valves a good choice for many uses throughout general industrial, oil and gas, and power generation installations.

Forged steel valves are available in a broad range of sizes, connection types, and port configurations. Crane, world class manufacturer of industrial valves, offers forged steel gate, globe, and check valves to provide options for flow direction, stop, and throttle control.

There are almost countless variants and configurations of industrial valves from which to choose. Share your fluid control requirements and challenges with an industrial valve expert, combining your own process knowledge and experience with their product application expertise to develop effective solutions.


Friday, March 17, 2017

Ergonomic Electro-Pneumatic Valve Positioner

Spirax Sarco, global leader in steam system control products, has released a new valve positioner that ranks high on the user friendly scale. The EP500 is an electro-pneumatic positioner that features a cast aluminum enclosure and a host of features that facilitate a rapid and simple setup or calibration procedure.

See how easily setup is accomplished, and get a close look at the new valve positioner, in the video provided below. Reach out to a steam system and valve specialist for more information, and share your control valve and steam system challenges. The combination of your own process knowledge and experience will combine with the expertise of a product application specialist to develop effective solutions.

Thursday, March 9, 2017

Metal Seated Ball Valves Offer Potential for Long Term Cost Savings

3 piece ball valve with handle
Adding metal seats to a ball valve can extend its service life
Photo courtesy of Flo Tite
The majority of ball valves are provided with one of several elastomeric materials forming a soft seat between the trim, or ball, and the valve body. With the balance of the valve assembly in contact with the media likely to be metal (unless, of  course, it is a plastic valve), the soft seat, because of its properties and location, tends to experience wear and tear and be a common cause for repair or valve performance deterioration.

In fluid process control applications where the media conditions may not, at first glance, warrant the use of a metal seated valve, there may be long term returns to be gained from the added cost of metal seats. The factors that create wear and degradation of soft seats are generally better tolerated by metal seats. Process downtime or man-hours for repair have a cost, so avoiding or reducing the occurrences of repair or maintenance provide a return on the additional expenditure for a metal seated valve that can provide a longer service life.

Many commonly available ball valves are also available with metal seats as an option, or metal seated variants are offered as uniquely identified products. Whatever the case, consider hardening your valve selections with metal seated valves. There are instances where they are well suited to the application and will offer a return on the additional cost.

Share your fluid process control challenges with a valve specialist, combining your own process knowledge with their product application expertise to develop effective solutions.



Thursday, March 2, 2017

New Electric Linear Actuators for Industrial Valves

electric linear valve actuators
Electric linear actuators for industrial valves
ILEA Series
Courtesy Warren Controls
There are uncountable choices for industrial process control valves and actuators. With applications so diverse and requirements so specific, each product seems to enjoy a placement within a particular niche or range of usage where it provides the perfect combination of construction, performance, and cost attributes.

Warren Controls, manufacturer of a wide range of industrial control valves and actuators that include both linear and rotary designs, has released an electrically powered linear actuator that provides some application advantages.

The ILEA series of industrial linear electric actuators provides failsafe features, fast operation, robust environmental performance, and extended output force ranges. This all is delivered at a cost point making the ILEA series a contender for any modulating valve service application.

The datasheet included below provides additional detail. Share your fluid process control valve challenges with valve application experts, combining your own process knowledge with their product application expertise to develop effective solutions.


Tuesday, February 21, 2017

Case Study From CSB: Industrial Plant Heat Exchanger Explosion

large shell and tube heat exchangers at industrial chemical plant
Primary and secondary heat exchangers, similar to the setup
in the re-enactment video
Industrial accidents, whether minor or catastrophic, can serve as sources of learning when analyzed and studied. Operators, owners, and technicians involved with industrial chemical operations have a degree of moral, ethical, and legal responsibility to conduct work in a reasonably and predictably safe manner without endangering personnel, property, or the environment. Part of a diligent safety culture should include reviewing industrial accidents at other facilities. There is much to learn from these unfortunate events, even when they happen in an industry that may seem somewhat removed from our own.

The U.S. Chemical Safety Board, or CSB, is an independent federal agency that investigates industrial chemical accidents. Below, find one of their video reenactments and analysis of an explosion that occurred at a Louisiana chemical processing plant in 2013. A portion of the reenactment shows how a few seemingly innocuous oversights can combine with other unrecognized conditions that result in a major conflagration.

Check out the video and sharpen your senses to to be aware of potential trouble spots in your own operation.

Wednesday, February 15, 2017

Trunnion Mount Ball Valves

stainless steel trunnion mount ball valve flange connections
One example of many variants for
trunnion mount ball valves
Courtesy HS Valve
A ball valve is generally a well understood industrial valve design. Its simple quarter turn operation, bidirectional sealing, compact form factor, and tight shutoff capability make the ball valve a preferred choice for many applications. The many variants of industrial ball valves can be grouped into two categories, distinguished by a primary design feature, the mounting of the ball.

The two designs are known as floating ball and trunnion mounted ball. Floating ball valves use the seats and body to hold the ball in place within the fluid flow path, with the force of directional flow pushing the ball against the downstream seats. The floating nature of the ball limits the applicability of this design to smaller valve sizes and pressure ranges. A some point, the fluid pressure exerted on the ball surface can exceed the ability of the seats to hold the trim effectively in place.

Trunnion mount ball valves employ the stem shaft and, you guessed it, a trunnion to support the trim. The shaft and trunnion, connected to the top and bottom of the trim, establish a vertical axis of rotation for the ball and prevent it from shifting in response to flow pressure. A trunnion is a pin that protrudes from the bottom side of the ball. It sits within a bearing shape, generally cylindrical, in the base of the body.

Because of their structural design, trunnion mount ball valves are suitable for all pressure ranges and sizes.They are used by many manufacturers as a basis of design for their severe service ball valve offerings. A trunnion mount ball valve can also be advantageous for applications employing valve automation. Since the ball is not held in place by a tight fitting seal arrangement, operating torque tends to be lower for comparably sized trunnion mount valves, when compared to floating ball valves.

Whatever your valve application challenge, share it with an industrial valve expert. The combining of your process expertise and experience with their product application knowledge will yield an effective solution.