Last updateMon, 30 Nov 2015 5pm


Power Plant Isolation Valves Beat the Heat

Power Plant Isolation Valves Beat the Heat

About a century ago, pressures of 300 ps...

NACE MR0175/ISO 15156 & NACE MR0103

NACE MR0175/ISO 15156 & NACE MR0103

Q: Is it possible to produce remanufactu...

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Industry Headlines


Industry Headlines

AUMA Supplying San Francisco Water Infrastructure Projects


AUMA is providing more than 250 actuators to 30 individual projects as part of the Water System Improvement Program (WSIP) led by the City and County of San Francisco Public Utility Commission, one of the largest water infrastructure programs in North America.

The WSIP is a major restoration initia...


Schlumberger-Cameron Union Receives Unconditional Clearance


Schlumberger Limited and Cameron International Corporation jointly announce that the U.S. Department of Justice has cleared their proposed merger without any conditions, granting early termination of the waiting period required by the Hart-Scott-Rodino Antitrust Improvements Act of 1976 with respect...


Global Petrochemical Prices Leveled Off in October


Prices in the $3-trillion-plus global petrochemicals market in October were virtually flat based on a monthly average, but edged slightly when valued on a month-end to month-end basis from September. This is the first time the markets have shown intermonth gains since May of this year, according to ...


U.S. Rig Count Less Than Half of Last Years Total


According to Baker Hughes, the U.S. rig count declined by 10 last week to 757. Of these 757 active rigs, 564 rigs are seeking oil and 193 are seeking natural gas.

Just a year ago, with oil prices nearly double what they now, there were 1,929 active rigs in the U.S.

The rig count was at its peak in...


Durable Goods Orders Up 3% In October


New orders for manufactured durable goods in October increased $6.9 billion or 3.0% to $239.0 billion, the U.S. Census Bureau announced. This increase, up following two consecutive monthly decreases, followed a 0.8% September decrease. Excluding transportation, new orders increased 0.5%. Excluding d...


Consumer Confidence Falls to 14-Month Low


The Conference Board Consumer Confidence Index, which had decreased moderately in October, declined further in November. The Index now stands at 90.4, down from 99.1 in October. The Present Situation Index decreased from 114.6 last month to 108.1 in November, while the Expectations Index declined to...


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.


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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