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Human Factors Can Cause a Disaster—or Prevent One

Human Factors Can Cause a Disaster—or Prevent One

Process industry plants are complex and ...

Improving Valve Sealing Performance and Reliability

Improving Valve Sealing Performance and Reliability

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A Primer on Fugitive Emissions

A Primer on Fugitive Emissions

Fourscore and seven years ago, no one ha...

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Industry Headlines

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Emerson Expanding Mississippi Facility

2 DAYS AGO

Emerson plans on delivering $500,000 in new equipment to its facility in Sherman, MS. Because of this investment , and its promise of new jobs for the region, the Sherman Economic Development Corp. has approved $150,000 in grants for Emerson.

"We have a relatively new Fisher product that will be reloca...

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REXA and CCC Form Joint Initiative

2 DAYS AGO

REXA and Compressor Controls Corporation (CCC) have formed a joint initiative to modernize steam turbine controls for enhanced performance based upon each company’s core competency.

There are more than 10,000 turbomachinery trains worldwide powered by CCC. By upgrading mechanical and hydraulic go...

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Chevron and Pembina Sign Deal to Build Pipelines, Other Facilities

1 DAY AGO

Calgary-based Pembina Pipeline Corp. has signed a 20-year deal with Chevron to build natural gas pipelines and processing facilities for a potential production operation in northwest Edmonton, Alberta. The infrastructure developed over the term of this agreement has the potential to represent a multi-...

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U.S. in Midst of Biggest Drilling Surge Since 2012

1 DAY AGO

“U.S. drillers pushed ahead on the biggest surge in oil drilling since 2012 as companies take advantage of oil prices that have held steady above $50 for almost three months,” Bloomberg reports .

“Drilling is booming in a few shale plays -- led by the Permian Basin in West Texas and Ne...

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U.S. Private Sector Growth Slows from January’s 14-Month Peak

2 DAYS AGO

At 54.3 in February, the seasonally adjusted Markit Flash U.S. Composite PMI Output Index dropped from 55.8 in January but remained above the 50.0 no-change value for the twelfth consecutive month. The latest reading signaled that private sector output growth moderated from the 14-month high recorded ...

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NAM Kicks Off Tour at Emerson Innovation Center in Austin

2 DAYS AGO

The National Association of Manufacturers (NAM) kicked off the 2017 State of Manufacturing Tour at Emerson Innovation Center in Austin, TX—a “hotbed of modern manufacturing.” The event is the first in a series of stops in six states throughout the next week, including a visit with Pr...

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When Accessories Become Necessities

vmspr10 beyond valves 1This automated valve assembly is made up of a process ball valve, pneumatically operated actuator, solenoid valve and inductive non-contact valve position sensor and target.Specification sheets for selecting automated valves list requirements for the valve and actuator but often lump all other devices together as related instrumentation or accessories.

Since the definition of an automated valve is a flow control device that can be remotely operated, a typical selection hierarchy is:

  1. Select the best valve for the service conditions
  2. Select a suitable actuator to operate that valve
  3. Provide enough information on accessories so the valve supplier or end user can just add them as needed.

A comprehensive valve data sheet may enumerate 40 to 50 line items of information that define the scope of the valve assembly. Since performance and safety of that assembly are greatly impacted if any component in the assembly fails, the more forethought put into the specification, the more likely the final assembly will perform as intended. The purpose of a specification is not to exclude any manufacturer but rather to include only those products the specifier perceives as most closely meeting the equipment application requirements.

THE SPEC SHEET

If we look at all system devices as necessities instead of accessories, we can divide the specification sheet into three sections.

  1. Under Process Components all devices that are in contact with the media would be listed. That would include the valve and instrumentation such as flow meters and other process variable transmitters.
  2. Under Force all devices that supply the motive power to operate the valve would be listed. This would include the actuator—pneumatic, electric or hydraulic; hand-wheel overrides; linkage kits/mounting brackets; solenoid valves; filter regulators; pressure gauges, etc.
  3. The third column would be headed Intelligence. This category would include valve position sensors. Intelligent devices interface the operator’s commands and the valve’s response. Without supervision/control, the automated valve will not function; therefore, the process will not function.

vmspr10 beyond valves 2The automated valve assembly shown here is for use in a hazardous location. It consists of a process ball valve with pneumatically operated actuator, solenoid valve and inductive NAMUR non-incendive valve position sensor and target. Note that the solenoid valve is driven from the valve position sensor, which simplifies wiring.Valve position sensors indicate to the plant operator that an automated or control valve is open, closed, or between open and closed. A valve position sensor or switch can take numerous forms: inductive proximity sensor, reed switch or mechanical switch. Sensors can be directly mounted to a rotary pneumatic actuator, bracket-mounted to a linear valve, enclosed inside a switch box or an electrically operated actuator, or inside a valve positioner.

An inductive proximity sensor is a non-contact device, which means the sensor is free from wear. A common metal target is mechanically attached to the actuator stem of a linear or rotary travel valve. When the target comes into range of detecting the sensor, an electronic switch changes state, which confirms the position of the valve. Actuation speed or frequency has no effect on inductive proximity sensors. They are typically used in pairs, one for the valve’s open position and another for the closed position, although sensing other positions can be easily accomplished. Dual sensors directly mounted onto a pneumatic actuator provide valve open and valve closed switching in one compact package. Proximity sensors are available in a variety of configurations and voltages and can be an integral part of a valve assembly, especially when the sensor’s full capabilities are utilized.

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