Protect Your Instrumentation with Diaphragm Seals

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

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 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

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.

Foxboro Instrumentation for Power Plants from Swanson Flo

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 (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.

Swanson Flo Performance Brochure

Swanson Flo specialize 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.

Swanson Flo Performance from Swanson Flo

Understanding Motor Operated Valves (MOV) in Industry

The video below demonstrates the operation a small (Worcester) motor operated ball valve (MOV). Also known as an “electric actuator”, motor operators come in a wide variety of sizes and styles. Some electric actuators are intended for quarter-turn valves (such as ball and butterfly valves), while others are designed to operate linear valves (such as gate and globe valves).

The MOV / electric actuator consists of an electric motor with the gearbox assembly which rotates the shaft of the valve. Most MOVs operate at 120, 240 or 480 volt, single or three phase. Basic features include adjustable limit switches to limit valve travel and to notify valve status, directional settings, analog inputs to allow for precise control, analog outputs to provide a feedback signal and digital communications. MOV enclosures can be either NEMA 4, NEMA 4X and NEMA 7 and are available in a wide range of torque outputs to match the valve it is operating.

Understanding Control Valves: The Flowserve Valtek Mark One

Control valves are an integral part of many process control loops. Understanding their basic operation is important for any process control professional. The following video demonstrates the reassembly of the Flowserve Valtek Mark One control valve and introduces the viewer to a control valve's main components.

There are a variety of styles of control valves. A globe control valve is a specific type of valve used for regulating flow in a pipe. The design includes a movable plug, connected to a stem, which can be moved linearly to close or open the valve. Globe control valves are referred to as “linear” valves because of this movement to open and close is directed by a piston type, linear movement actuator. Generally, globe control valves provide better overall flow control than quarter-turn valves due to the design of their flow path.

For more information, a Valtek Mark One specification sheet is also included with this post.

Flowserve Valtek Mark One Control Valve from Swanson Flo