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Introduction to Pressure Relief Devices - Part 1

Introduction to Pressure Relief Devices - Part 1

When the pressure inside equipment such ...

Is Your Company Ready for The New Reality?

Is Your Company Ready for The New Reality?

Since August, 2015, when VMA’s 201...

Offshore Oil Extraction and Transportation

Offshore Oil Extraction and Transportation

Offshore oil facilities come to the fore...

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Industry Headlines

ITT Reports 2015 Fourth-Quarter, Full-Year Results

7 HOURS AGO

On a GAAP basis, ITT delivered revenue of $2.5 billion in 2015, reflecting a 6% decline, primarily due to the impact of unfavorable foreign exchange of $194 million. GAAP operating income increased 43%.

Organic revenue in the Industrial Process segment decreased 6%, reflecting strength in short-cyc...

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MRC Global Signs Agreement to Sell OCTG Business

1 DAY AGO

MRC Global Inc. has entered into a definitive agreement to sell its U.S. Oil Country Tubular Goods (OCTG) business to Sooner Pipe, LLC, a subsidiary of Marubeni-Itochu Tubulars America, Inc., for $48 million, subject to certain adjustments.

MRC Global's U.S. OCTG sales were approximately $305 milli...

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EPA Halts Implementation of Clean Power Plan

5 HOURS AGO

Earlier this week, in a 5-4 decision, the U.S. Supreme Court granted an industry motion to stay the EPA’s Clean Power Plan while the lower courts determine its legality. Last fall a lawsuit was filed on behalf of more than two dozen states, utilities and industry groups.

“States did not...

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IHS: North American Drillers Need Billions More in Cuts

2 DAYS AGO

The depressed oil price environment is painting a gloomy outlook for North American exploration and production (E&Ps) companies, and further, significant CAPEX cuts are needed in order for the group to demonstrate real financial discipline and align spending more closely with cash flow, accordin...

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U.S. Job Openings Climb to Second-Highest Level on Record

3 DAYS AGO

The number of job openings increased to 5.6 million in December, the second highest number ever recorded, the U.S. Bureau of Labor Statistics reported today. Hires and separations were little changed at 5.4 million and 5.1 million, respectively. Within separations, the quits rate was 2.1%, and the l...

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Machine Tool Orders Rose in December, Down in 2015

3 DAYS AGO

The U.S. Manufacturing Technology Orders report for December 2015 showed that order values grew 20.4% compared to the prior month, according to The Association for Manufacturing Technology (AMT). For all of 2015, the year’s total orders were down 17.4% compared to 2014.

While the month-to-mon...

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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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