Showing posts with label Montana. Show all posts
Showing posts with label Montana. Show all posts

8 Critical Control Valve Selection Criteria

Control Valve (Valtek)
Control Valve (Valtek)
Choosing an improperly applied sized or improperly sized control valve can have serious consequences on operation, productivity and most important, safety. Here is a quick checklist of basics that need to be considered:
  1. Control valves are not intended to be a an isolation valve and should not be used for isolating a process. 
  2. Always carefully select the correct materials of construction. Take into consideration the parts of the valve that comes in to contact with the process media such as the valve body, the seat and any other "wetted" parts. Consider the operating pressure and operating temperature the control valve will see. Finally, also consider the ambient atmosphere and any corrosives that can occur and effect the exterior of the valve. 
  3. Put your flow sensor upstream of the control valve. Locating the flow sensor downstream of the control valve exposes it to an unstable flow stream which is caused by turbulent flow in the valve cavity.
  4. Factor in the degree of control you need and make sure your valve is mechanically capable. Too much dead-band leads to hunting and poor control. Dead-band is roughly defined as the amount of control signal required to affect a change in valve position. It is caused by worn, or loosely fitted mechanical linkages, or as a function of the controller setting. It can also be effected by the tolerances from mechanical sensors, friction inherent in the the valve stems and seats, or from an undersized actuator. 
  5. Consider stiction. The tendency for valves that have had very limited travel, or that haven't moved at all, to "stick" is referred to as stiction. It typically is caused by the valves packing glands, seats or the pressure exerted against the disk. To overcome stiction, additional force needs to be applied by the actuator, which can lead to overshoot and poor control.
  6. Tune your loop controller properly. A poorly tuned controller causes overshoot, undershoot and hunting. Make sure your proportional, integral, and derivative values are set). This is quite easy today using controllers with advanced, precise auto-tuning features that replaced the old fashioned trial and error loop tuning method.
  7. Don't over-size your control valve. Control valves are frequently sized larger than needed for
    Control Valve Specialized Kammer
    Control Valve
    Specialized for Food/Bev
    Pharmaceutical (Kammer)
    the flow loop they control. If the control valve is too large, only a small percentage of travel is used (because a small change in valve position has a large effect on flow), which in turn makes the valve hunt. This causes excessive wear. Try to always size a control valve at about 70%-90% of travel.
  8. Think about the type of control valve you are using and its inherent flow characteristic. Different types of valve, and their disks, have very different flow characteristics (or profiles). The flow characteristic can be generally thought of as the change in rate of flow in relationship to a change in valve position. Globe control valves have linear characteristics which are preferred, while butterfly and gate valves have very non-linear flow characteristics, which can cause control problems. In order to create a linear flow characteristic through a non-linear control valve, manufacturers add specially designed disks or flow orifices which create a desired flow profile.
These are just a few of the more significant criteria to consider when electing a control valve. You should always discuss your application with an experienced application expert before making your final selection.

Consider Flangeless Wafer Style Control Valves for Excellent Flow Control

Mark 75 Flangeless Wafer Style Control Valve
Jordan Mark 75 Flangeless
Wafer Style Control Valve
Valves are essential to industries which constitute the backbone of the modern world. The prevalence of valves in engineering, mechanics, and science demands that each individual valve performs to a certain standard.

One category of valves are "control valves". These can be linearly operated, or rotary operated. There are many types of control valves, such as gate, globe, ball, butterfly, and plug. All of these valve types have some sort of ball, plug, gate, or disc that throttles the flow as the valve opens and closes. Some valve designs are better suited to uniformly control flow, such as gate valves or valves with specially machined disks. This post is about the Jordan Mark 75, a valve that uses a unique sliding gate design.

According to Wikipedia, "A control valve is a valve used to control fluid flow by varying the size of the flow passage as directed by a signal from a controller. This enables the direct control of flow rate and the consequential control of process quantities such as pressure, temperature, and liquid level."

The Mark 75 Series control valve is a industrial process control valve manufactured by Jordan Valve. It's design benefits include the sliding gate seat design, low weight, and compact wafer style body. The Mark 75 offers an incredible pricing advantage in the market place due to its wafer style body.

The stroke length of the Mark 75 is a slightly longer stroke than standard sliding gate valves. This longer stroke enables better turndown. Combined with the capacity of the Mark 75, the increased turndown makes for a great control valve.

Please watch the video below, and see the specification sheet at the bottom for further details. For more information about this valve, or any Jordan Valve product, contact Swanson Flo at 800-288-7926 or visit http://www.swansonflo.com.


Understanding Industrial Rack and Pinion Valve Actuators

Basic concept of rack and pinion gear
Basic concept of
rack and pinion gear.
Valves are essential to industries which constitute the backbone of the modern world. The prevalence of valves in engineering, mechanics, and science demands that each individual valve performs to a certain standard. Just as the valve itself is a key component of a larger system, the valve actuator is as important to the valve as the valve is to the industry in which it functions. Actuators are powered mechanisms that position valves between open and closed states.

Pneumatic rack and pinion actuators utilize air pressure as the motive force which changes the position of a valve.  A rack and pinion actuator is comprised of two opposing pistons, each with its own gear (referred to as the "rack"). The two piston racks are set against a round pinion gear. As pressure increases against one side of each piston, each rack moves linearly against the opposite sides of the pinion gear causing rotational movement. This rotational movement is used to open and close a valve. See the animation above (provided by Wikipedia) below for a visual understanding.

This short video introduces the basic parts and operation of rack and pinion valve actuators to anyone unfamiliar with the device.


Visit http://www.swansonflo.com to learn more about industrial valves, valve actuators, and valve automation.

Pressure Instrument Calibration

Calibration of pressure instruments
Proper pressure instrument calibration is critically
important for safety and quality.
Calibration of pressure instruments in industrial environments requires the establishment of known pressure magnitudes. With a stable input pressure established, the pressure measurement instrument is provided with a referential benchmark that can be used to evaluate instrument output. There are several physical test standards or methods that can be applied to pressure instruments.

A deadweight tester, sometimes called a dead-test calibrator, creates accurately known pressure using precise masses and pistons of a known area. The gauge or pressure instrument is connected to the deadweight tester. The device is comprised of tubes that contain either oil or water, with a primary piston positioned above the liquid and a secondary piston across from the place where the gauge connects to the tester. A mass of a known quantity is placed atop the primary piston, which is perfectly vertical. The earth's gravitational field acts upon the mass atop the piston. The combination results in a known value being applied to the deadweight tester and subsequently allows for calibration of the gauge.
deadweight tester
Deadweight tester (Ashcroft)

Once pressure builds inside the deadweight tester, surpassing the weight of the piston, the piston will rise and float atop the oil. By rotating the mass atop the piston, the piston will rotate inside its cylinder and negate any impact from friction. Developments in technology have led to testers being equipped with hand pumps and bleed valves. The same principles applied to a deadweight tester which uses oil are applied to a pneumatic deadweight tester, where gas pressure suspends the mass atop the cylinder instead of oil or water pressure.

The manometer is another device which establishes a pressure standard to calibrate gauges. Alone, the manometer is simply a U shaped tube connecting a source of fluid pressure to the gauge being calibrated. Pressure applied to the gauge will be indicated by the corresponding heights of the fluid in the columns. If the value of the density of the liquid is a precise, known value, the aforementioned constant of the earth's gravitational field will combine with the applied pressure to permit calibration of the gauge.
Digital Test Gauge
Digital Test Gauge (Ashcroft)

Test instruments which couple with the calibration of pressure transmitters are also instrumental in ensuring correct pressure calibration. Electronic and pneumatic test instruments, along with precise air pressure calibration pumps, enable calibrating a pressure transmitter in place, in the field, or on a lab bench. These portable devices, though, require their own calibration to physical standards with referenced properties. While different devices exist for establishing pressure standards in either high or low pressure environments, the shared standard allows for varying types of instrumentation to exhibit similar performance quality and accomplish the same task.

Contact Swanson Flo for any pressure instrument repair or calibration requirement. Visit http://www.swansonflo.com or call 800-288-7926.

A Proven Actuator Ideal for Valves Requiring Rotary or Linear Movement

Limitorque L120 electric actuator
Limitorque L120 electric actuator.
Whether used with gate valves, globe valves, penstocks or sluice gates, versatile Limitorque L120 Series actuators operate without modification in any rising or non-rising stem application for linear-action valves.

When combined with a Limitorque WG or HBC series quarter-turn gear operator, L120 actuators can also be used to control butterfly, ball and plug valves, as well as damper drives, flop gates or any other device which requires rotary movement.

L120 actuators are specified for use in petrochemical, power generation, and water and waste treatment applications where failure of a single actuator can be extremely costly … even catastrophic.

For more information on Limitorque actuators, visit Swanson Flo's website or call 800-288-7926.

For your convenience, below you will find the Limitorque L120-85 installation and operation manual.


What are purged impulse lines and why are they needed?

Purged impulse lines
Diagram of a purged impulse line implementation.
(image courtesy of Lessons in Industrial Instrumentation
by Tony R. Kuphaldt
)
Purged impulse lines, or sensing lines, allow process transmitters and gauges to maintain operation under potentially adverse process conditions that may impact the operation or accuracy of the instrument. The purging of an impulse line is of particular use when sensing lines may have a high susceptibility to plugging by the process fluid. The line is purged with clean fluid at a constant rate, meaning new fluid is always being introduced into the impulse line. When the purge is properly set, a critical element of successful implementation, the pressure instrument is still able to correctly measure system pressure.

Purging a sensing line will require additional valves and devices to properly control the purge fluid flow and provide for effective maintenance or repair. Because of the increased relative complexity, a purging setup will likely be employed only in cases where other methods of maintaining clear sensor lines and proper instrument operation have been considered and rejected. The impulse line will stay free of sedimentation thanks to the purge fluid, and process fluid contamination of the sensing line is avoided.

One of the most important parts of the purged impulse line system is a restriction, implemented to prevent the pressure instrumentation from sensing the elevated pressure of the purge fluid supply instead of measuring the original process fluid. The purge valve, through which the purge fluid flows, is left partially open instead of fully open. If the restriction does not mitigate the introduction of the purge fluid on the process line, then the flow rate of the purge fluid can adversely impact the process measurement. It is essential that purge flow be regulated in a manner that does not adversely impact the measurement of actual process conditions.

A basic requirement of sensing line purge systems is that the supply of purge fluid needs to be flowing at all times. Additionally, the purge fluid supply pressure must be maintained at a level greater than the process pressure because if the pressure of the purge fluid supply drops below the process pressure, the process fluid will flow into the impulse line. The purge fluid must also not react negatively with or contaminate the process and will be continuously consumed. Generally, purge rates are kept as low as possible, mitigating purge fluid impact on the process measurement and keeping the cost low. A rotameter, which indicates visual flow of the purge fluid, is an item typically paired with purge impulse line systems, and there are many options available for use as purge fluids.

Common gases for purged impulse lines include air, nitrogen, and carbon dioxide. A purge system can be applied to both gas and liquid process systems. Share your process measurement challenges with instrumentation specialists. Combine your own process knowledge and experience with their product application expertise to develop effective solutions.

Swanson Flo Performance

Specialists in valves, automation and instrumentation, Swanson Flo Performance sets the standard for process control optimization and training that maximizes plant uptime, safety and operating efficiency.
  • Valve automation center 
  • Experienced staff of factory-certified technicians 
  • Responsive on-call repair and service 
  • Extensive OEM parts inventory 
  • Third party audited standards 
  • The region’s widest range of industry application experience 
  • Comprehensive multi-brand process equipment knowledge
Please take a minute to watch the video below for more information.

Self-Operating Temperature Regulators

Jordan Mark 80
Jordan Mark 80
In process control applications, exceedingly close control with PID loops is not always necessary. There can also be instances where location or operational circumstance calls for temperature control, but not necessarily under the control of a centralized system. Self operated mechanical temperature regulators, with their reliable and simple operating scheme, can be well suited for these applications.

Self operated temperature regulators are basically valves with self contained actuation controlled by a filled system, or bulb. The valve portion of the assembly controls the flow of a fluid which impacts the process temperature. The process temperature is measured by a fluid filled bulb, connected via a capillary to a chamber containing a diaphragm. As the temperature of the process changes, the fluid in the bulb expands or contracts, changing the fluid pressure on the diaphragm. Pressure on the diaphragm causes movement, which is linked to the sliding gate trim of the valve, thus adjusting fluid flow. A spring provides a counteractive force on the diaphragm and allows for setpoint adjustment.

The self contained assembly requires no external power source to operate and requires little maintenance. Proper selection of line size, capillary length, bulb type, and temperature range are key elements in getting the right valve for the job. Application temperature ranges from -20 to +450 degrees Fahrenheit.

The Mark 80 Series Temperature Regulator features the advanced sliding gate seat technology pioneered by Jordan Valve. Using the Jordan Valve sliding gate seat technology, the Mark 80 temperature regulators have the signature straight-through flow, short-stroke that is 1/3 of a globe-style valve, quiet operation and tight shutoff. The Jordan Valve Mark 80 has high rangeability and extremely accurate regulation. The proprietary Jorcote seat material is extremely hard (@RC85) with a low coefficient of friction that delivers outstanding performance and long service life.
Share your temperature control and fluid flow challenges with product application specialists, combining you own process expertise with their product application know-how to develop the most effective solutions.

You can see all the details in the datasheet included below. For more information contact Swanson Flo by calling 800-288-7926 or visit http://www.swansonflo.com.

Choosing Temperature Sensors for Industrial HVAC and Chiller Equipment

Minnesota, Iowa, Wisconsin, Nebraska, Illinois, Indiana, North Dakota, South Dakota, Montana, Wyoming, Michigan,
Sensors used in HVAC
Reprinted with permission from Gems Sensors & Controls white paper.

Efficient operation of industrial HVAC and chiller equipment depends upon optimum temperatures of refrigerant and lubricating oil at various phases of the refrigeration cycle. The most common sensors for this purpose utilize negative temperature coefficient (NTC) thermistors of various resistance values. NTC sensor devices exhibit lower electrical resistance when exposed to higher temperatures.

RTD for HVAC
RTD
Either thermistor or RTD-type sensors may be used for this purpose, however thermistors are preferred for most applications due to cost and media exposure attributes. RTDs are more expensive, and the fragility of the sensing element require it to be separated from the sensed media within an enclosure. Thermistors are more durable, and may be immersed directly in any non-conductive fluid media being sensed, for quicker response to temperature changes. There is an inherent non- linearity in thermistor output that requires temperature and resistance correction for the output. Manufacturers of thermistors, and sensors made from them, can provide Resistance-to-Temperature curves for this purpose.

Assuming equivalent thermistor quality and resistance values, combining the thermistor within a housing that can be installed into HVAC or chiller equipment is what differentiates one sensor assembly from another. These fall into two basic types: exposed or enclosed thermistor housings.

Open thermistor probe
Open sensor thermistor probe.
Exposed thermistors directly contact the fluid being sensed; in this application, those are refrigerant, oil, and oil/refrigerant emulsion, although they may be used in any non-conductive fluid. Direct contact with fluids provides faster and more accurate thermistor response. The downside to exposed thermistor sensors is leakage through the housing where the thermistor leads pass through sensor housings, especially in pressured installations. Leakage results in maintenance downtime for the operator and warranty issues for the equipment manufacturer.

Enclosed thermistors encase the thermistor inside a probe that is an integral part of the housing. These eliminate the leakage issue, but because the thermistor is actually in an air pocket surrounded by the metal or plastic housing, temperature compensation and sensor responsiveness issues are introduced.


A Recent Third Option

Gems Sensors & Controls has produced a third type of housing that combines the performance of an exposed thermistor design, while providing the hermetic sealing of an enclosed sensor housing. Known as the TM-950 Series, these thermistor-based temperature sensors were designed specifically to solve long-term reliability issues in HVAC and Chiller applications.

TM-950 Series temperature sensor incorporates a unique fused-glass technique to produce a hermetically sealed the housing. Molten glass is placed inside the heated housing. As the assembly cools the metal housing shrinks, compressing the glass. In addition, the boundary surface of heated metal and glass bond at a molecular level. Two nickel-plated steel tubes are positioned pre-positioned before the glass fusing process to provide a pass through for the thermistor leads. Any of a variety of thermistors may be utilized based on the temperature sensing profile required. Once leads are passed through the steel tubes and glass, induction soldering fills the tubes completely, providing a leak-proof seal to 450 psig. The result is a sensor with the benefits of direct fluid contact incorporating the leak-proof attributes of an enclosed sensor.

For more information on selecting sensors for industrial HVAC applications and chillers visit Swansonflo.com or call 800-288-7926

A Look Inside the Cashco Ranger QCT Industrial Control Valve

Cashco Ranger QCT Industrial Control Valve
Cashco Ranger QCT
Industrial Control Valve
The Cashco Ranger is one of the most popular industrial control valves on the market. It is the most versatile, adaptable, and easily maintainable valve ever produced. No other valve is more user friendly.

The Ranger offers over 6 different trim combinations. Trim can easily be changed in less than 5 minutes without disturbing the packing, actuator, or positioner calibration. The service area is a thread-less design, which resists corrosion or collection of chemical deposits.

A selection of 3 body materials with a broad temperature range from -325°F to +750°F makes the Ranger adaptable for use in steam, heat transfer fluids, slurries, gases, liquids, and cryogenic applications. The Ranger’s unique dual seating design provides both Class VI and backup Class IV seat leakage. And the standard patented live-loaded packing system lets you check and adjust packing without the need for specialized tools or complicated procedures.

Check out the video below for a detailed look. For more information, visit Swanson Flo at http://www.swansonflo.com or call (510) 274-1990.

Lined Industrial Valves for Corrosive Service

Lined Durco Plug Valves
Lined Plug Valves
(courtesy of Flowserve Durco)
Lined valves use a fluoropolymer, plastic, or ceramic lining applied to all wetted internal parts of the valve.

Lined valves combine the excellent mechanical properties of metallic bodies with the corrosion resistance of fluorocarbons, such as PFA and PTFE.

Lining the intricately shaped inside surfaces of a valve is certainly an engineering challenge, especially to achieve a uniform thickness and the highest lining quality, without cavities or inclusions.

Lined Valves
Lined ball and swing check valve
(courtesy of Flowserve Atomac)
The special lining process guarantees tight bonding between the lining and the inside of the body.
This effectively prevents the lining from shearing off the body in part or being removed completely.

Ideal applications include highly corrosive applications within the chemical processing industry such as sulfuric and hydrochloric acid.

Lined valves are ideally suited for corrosive applications, requiring very reliable performance, tight shutoff, constant torque and no maintenance. These valves have gained extensive usage in many industries including power generation, pulp and paper, refineries, chemical process, pharmaceutical/bioprocessing and pollution control.

For more information on lined valves, visit Swanson Flo at http://www.swansonflo.com or call 800-288-7926.

Magnetic Flowmeters (Magmeters): Principles and Applications

Magnetic flowmeter
Magnetic flowmeter (Foxboro)
Crucial aspects of process control include the ability to accurately determine qualities and quantities of materials. In terms of appraising and working with fluids (such as liquids, steam, and gases) the flowmeter is a staple tool, with the simple goal of expressing the delivery of a subject fluid in a quantified manner. Measurement of media flow velocity can be used, along with other conditions, to determine volumetric or mass flow. The magnetic flowmeter, also called a Magmeter, is one of several technologies used to measure fluid flow.

In general, magnetic flowmeters are sturdy, reliable devices able to withstand hazardous environments while returning precise measurements to operators of a wide variety of processes. The magnetic flowmeter has no moving parts. The operational principle of the device is powered by Faraday's Law, a fundamental scientific understanding which states that a voltage will be induced across any conductor moving at a right angle through a magnetic field, with the voltage being proportional to the velocity of the conductor. The principle allows for an inherently hard-to-measure quality of a substance to be expressed via the Magmeter. In a Magmeter application, the meter produces the magnetic field referred to in Faraday's Law. The conductor is the fluid. The actual measurement of a magnetic flowmeter is the induced voltage corresponding to fluid velocity. This can be used to determine volumetric flow and mass flow when combined with other measurements.

The magnetic flowmeter technology is not impacted by temperature, pressure, or density of the subject fluid. It is however, necessary to fill the entire cross section of the pipe in order to derive useful volumetric flow measurements. Faraday's Law relies on conductivity, so the fluid being measured has to be electrically conductive. Many hydrocarbons are not sufficiently conductive for a flow measurement using this method, nor are gases.

Magmeters apply Faraday's law by using two charged magnetic coils; fluid passes through the magnetic field produced by the coils. A precise measurement of the voltage generated in the fluid will be proportional to fluid velocity. The relationship between voltage and flow is theoretically a linear expression, yet some outside factors may present barriers and complications in the interaction of the instrument with the subject fluid. These complications include a higher amount of voltage in the liquid being processed, and coupling issues between the signal circuit, power source, and/or connective leads of both an inductive and capacitive nature.

In addition to salient factors such as price, accuracy, ease of use, and the size-scale of the flowmeter in relation to the fluid system, there are multiple reasons why Magmeters are the unit of choice for certain applications. They are resistant to corrosion, and can provide accurate measurement of dirty fluids - making them suitable for wastewater measurement. As mentioned, there are no moving parts in a Magmeter, keeping maintenance to a minimum. Power requirements are also low. Instruments are available in a wide range of configurations, sizes, and construction materials to accommodate various process installation requirements.

As with all process measurement instruments, proper selection, configuration, and installation are the real keys to a successful project. Share your flow measurement challenges of all types with a process measurement specialist, combining your process knowledge with their product application expertise to develop an effective solution.

The video below provides additional information about magnetic flowmeters.


Your Partner for Process Control Automation: Swanson Flo

Founded in 1960, Swanson Flo has long maintained our position as an industry leader in process automation with unmatched project success leveraging industry preferred products and services.

Our mission is to provide innovative process control solutions for engineers, managers and maintenance professionals through quality equipment and experienced application engineering. These efforts combined with excellent aftermarket service yield reduced operating costs and improved production. Visit http://www.swansonflo.com or call 800-288-7926.

Ashcroft Awards Swanson Flo Coveted "Distributor of Distinction Award"

For the fourth consecutive year, pressure and temperature instrument manufacturer Ashcroft, Inc. named Swanson Flo of Plymouth Minnesota the Ashcroft "Distributor of Distinction" for 2016. This award recognizes and honors Ashcroft Distributors who deliver exceptional growth, revenue, and commitment, and stands as Ashcroft's most respected and highest honor for their Distributors.

Swanson stood out from the pack in 2016 with a 17% increase in bookings over their previous year, despite a very tough economy for industrial distribution. Swanson Flo attributes the increase to their focus on developing new business at targeted accounts, increasing the size of their sales force, and turning up new applications at existing accounts.

From left to right:  Bill Johnson, Sales Manager, Western Division;
Robbin Jensen, Insides Sales Manager; Tom Howe, Owner/CEO,
Sandy Grinvalds, Ashcroft; and Sid Sondag, Director Sales & Marketing.

The Advantages of the Sliding Gate Control Valve Seat in Process Control

Sliding Gate Control Valve Seat
Sliding Gate Control Valve Seat (Jordan)
Fluid flow control in a process can present a number of challenges, large and small. In addition to selecting a properly sized control valve, your choice of trim design can contribute noticeably to overall positive performance. One candidate for fluid flow control is the sliding gate valve.

The trim of a sliding gate valve essentially consists of a fixed disc and a movable plate installed directly in the flow path. The disc and plate have precisely located and sized perforations, slots, or other openings. The valve actuation mechanism slides the plate across the face of the disc, progressively changing the alignment of the openings in the plate and fixed disc. This type of design can bring some benefits to the process and user:

  • Short stroke length provides fast response, reduces wear on packing and diaphragm, allows for a compact installed assembly
  • Straight-through flow pattern reduces turbulence, noise, erosion, valve chatter, and cavitation
  • Ease of maintenance, with fewer trim components that are easily changed
  • Self cleaning, self lapping seats

The video below provides a clear illustration of how the sliding gate valve trim works, through animation and exploded views of the valve components. Share your fluid flow control challenges with a valve specialist and combine your process expertise with their product application knowledge for an effective solution.

Continuous Non-contact Level Measurement for Process Control

LLT 100 Laser Level Transmitter
LLT 100 Laser Level
Transmitter
ABB has released the new Model LLT 100 Laser Level Transmitter, which provides continuous non-contact level measurement for process automation and inventory management across a broad range of industrial applications.

The new transmitter provides reliable level measurement of solids or liquids, even clear liquids. The laser ranging technology is packaged with features required by industrial applications. Currently, three variants include housings for general industrial applications, as well as another for high pressure and one for hygienic installation.

The video blow provides a clear overview of the benefits that accrue from selecting this technology for your next project. More information is available from application specialists, with whom you should share your requirements and challenges to develop effective solutions.

Protect Your Instrumentation with Diaphragm Seals

Flanged diaphragm seal
Flanged diaphragm seal
(Ashcroft)
Pressure measurement is a common element of industrial operations and control systems. Fluid processing can often involve media that is potentially harmful to pressure sensing devices. The media may be corrosive to the sensor material, or other media properties may impact the performance or usable life of the instrument. In process control environments, diaphragm seals play a role in protecting items like pressure sensors from damage by process fluids.

The diaphragm seal is a flexible membrane that seals across the connecting path to a sensor and isolates the sensor from the process media. System pressure crosses the barrier without inhibition, enabling accurate measurement, but the process fluid does not. Typical materials composing diaphragm seals are elastomers, with a wide variety of specific materials available to accommodate almost every application.

In the operating principle of the diaphragm seal, the sealed chamber created between the diaphragm and the instrument is filled with an appropriate fluid, allowing for the transfer of pressure from the process media to the protected sensor. The seals are attached to the process by threaded, open flange, sanitary, or other connections.  Diaphragm seals are sometimes referred to as chemical seals or gauge guards. Stainless steel, Hastelloy, Monel, Inconel, and titanium are used in high pressure environments, and some materials are known to work better when paired with certain chemicals.
Threaded diaphragm seal
Threaded diaphragm seal

Sanitary processes, such as food, beverage, and pharmaceuticals, use diaphragm seals to prevent the accumulation of process fluid in pressure ports, a possible source of contamination. If such a buildup were to occur, such as milk invading and lodging in a port on a pressure gauge, the resulting contamination compromises the quality and purity of successive batches. Extremely pure process fluids, like ultra-pure water, could be contaminated by the metal surface of a process sensor. Some 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.

Sanitary diaphragm seal with gauge
Sanitary diaphragm
seal with pressure gauge.
Diaphragm seals are not without some application concerns, and devices are now built to address and counter many potential issues related to the use of diaphragm seals with process monitoring instruments and equipment. 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 improved performance while ensuring protection from corrosion.

There are numerous options and available diaphragm seal variants. Share your application specifics with a product specialist, combining your own process knowledge and experience with their product application expertise to develop an effective solution.

Measurement and Control Instruments for the Power Industry

Control Instrumentation for Power Plants
Coal fired power plant.
The coal-fired power generation and combined-cycle power generation industry now demands much more of its control and instrumentation suppliers. Common areas for use are fuel systems, fermenters, gas storage, water treatment, boiler feed water, boiler drum, steam line, cooling water system, generator, condenser, gas cleaning system, flue gas desulfurization, residuals storage and stack.

The document below provides a visual guide of common applications and the instrumentation products that have proven track records in those applications.

Flowserve Valtek Valve Automation

The video below highlights several Swanson Flo automated Valtek control valves. Included in these systems are Valtek ShearStream segmented ball valves, Valtek Valdisk BX butterfly valves, Logix positioners, Valtek VR piston actuators, and StoneL Axiom valve monitors.


Swanson Flo is a premier valve and valve automation supplier located in Plymouth, MN with warehouse and fabrication facilities in Addison, IL, Indianapolis, IN and Menomonee Falls, WI.

Visit Swanson Flo at http://www.swansonflo.com or call 800-288-7926 with any valve automation project.

Swanson Flo Valve Automation Services

42 inch electrically actuated butterfly valve
42 inch electrically (Limitorque) actuated butterfly valve.
Swanson Flo, an industrial valve and control company headquartered in Plymouth, Minnesota is also one of North America's leading valve automation specialists.

From simple, small pneumatic or electrically actuated valves, to very large, critical-control valve systems, Swanson Flo delivers tested, certified, and reliable product to customers located in the Upper Mid-West. Swanson Flo designs, engineers, and assembles actuated valve assemblies for the best fit, highest performance, and optimal application life. Their engineers and technicians combine decades of experience and knowledge. Coupled with a broad variety of carefully selected, readily available components, Swanson Flo customers are provided the best quality and best value possible.

Building upon 50+ years of industry and applications experience, Swanson Flo boasts the largest, most comprehensive automation facility in the mid-west, with capabilities for electric, pneumatic and electro-hydraulic actuation. A team of experienced design engineers and fabrication technicians construct automated valve systems from virtually any valve, actuator, monitor or positioner technology.

For more information, visit http://www.swansonflo.com or call 800-288-7926.