09262017Tue
Last updateMon, 25 Sep 2017 6pm

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Carbon Capture and Storage: Why and How?

Carbon Capture and Storage: Why and How?

Carbon (CO 2 ) capture and storage (CCS) i...

Can Valves Mitigate Flooding from Severe Weather Events

Can Valves Mitigate Flooding from Severe Weather Events

Hurricanes Harvey and Irma have certainl...

Machine Learning: A Brave New World

Machine Learning: A Brave New World

Whether you embrace it as a way to more ...

The Road to Valve Knowledge

The Road to Valve Knowledge

Valve expertise is a journey, not a dest...

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Industry Headlines

Permian ‘Super Basin’ Holds Trillions in Untapped Oil

Monday, 25 September 2017  |  Chris Guy

Energy researchers at IHS Markit have completed the first, three-year phase of a massive Permian Basin research project that models and interprets the...

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Industry Headlines

Flowserve Appoints Lee Eckert as CFO

14 HOURS AGO

Flowserve has named Lee Eckert as senior vice president and chief financial officer (CFO), effective October 9, 2017. Eckert joins Flowserve from CHC Group LLC., a global commercial helicopter service provider to the offshore oil and gas industry, where he served as senior vice president and CFO since...

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Velan Announces New Sales Structure

4 DAYS AGO

Velan is re-designing its sales structure to be better aligned with customers’ market approach. This change is intended to focus Velan’s resources on maximizing impact and competitiveness in today’s challenging economy.

Paul Dion has been appointed as vice-president of sales, process ...

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Permian ‘Super Basin’ Holds Trillions in Untapped Oil

8 HOURS AGO

Energy researchers at IHS Markit have completed the first, three-year phase of a massive Permian Basin research project that models and interprets the giant basin’s key geologic characteristics to better estimate its remaining hydrocarbon potential, and initial results indicate the giant basin ...

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DowDuPont Opens New Ethylene and Plastics Plant in Texas

10 HOURS AGO

DowDuPont Materials Science announced the startup of its new integrated world-scale ethylene production facility and its new ELITE enhanced polyethylene production facility, both in Freeport, TX. Both units will continue to ramp up through the third quarter and are expected to reach full rates in the ...

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U.S. Manufacturers Seeking More Renewable Energy

4 DAYS AGO

A new report from David Gardiner and Associates finds that 83% of the largest manufacturing companies with a U.S. footprint have established greenhouse gas reduction targets and 25% of manufacturers have established renewable energy targets. The analysis also finds that enabling access to renewable en...

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Harvey Caused Steep Drop in U.S. Industrial Output

7 DAYS AGO

Industrial production declined 0.9% in August following six consecutive monthly gains. Hurricane Harvey is estimated to have reduced the rate of change in total output by roughly 0.75%. The index for manufacturing decreased 0.3%; storm-related effects appear to have reduced the rate of change in facto...

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Don't Overlook Linear Actuators on Gate Valves

At a recent sales meeting in California, I was surprised to discover the lack of awareness regarding linear valve actuators. In fact, one veteran of the valve industry remarked, "I didn't know you could operate a gate valve using compressed air and a linear actuator." Most folks in the valve industry are familiar with operating globe valves in this manner, but typically, multi-turn electric actuators have been used when automating gate valves. However, if the control application calls for faster stroke speed, mechanical failure position, precise positioning, or higher thrust, linear pneumatic or hydraulic actuators may be preferred.

The basic principle behind linear actuators is simple: a piston in a cylinder. This type of actuator is very simple and reliable; after all, it only has one moving part. Such a mechanical device has been around for more than 200 years. Pistons in cylinders first saw use in steam engines. Scotland's James Watt crafted the first good ones during the 1770s.

Attaching a linear actuator to a gate valve is fairly straightforward. First, the handwheel and drive nut comes off, exposing the threaded stem. Then, a coupling is used to connect the stem to the piston rod. This allows the linear actuator to move the stem up and down directly. The before-and-after pictures on the left and right, respectively, show the change from a manual valve to an automatic valve with the linear actuator.

Of course, the actuator is now producing "thrust" not "torque," and this is a critical specification for linear actuator design. As it turns out, the size of the cylinder is a function of the required valve thrust and the available supply (pressure x area = force). The cylinder is larger for a higher required thrust and a lower supply pressure. And since the actuator price increases as the cylinder size increases, engineers must verify that the supply pressure given is the highest available at the project site.

Moreover, if the calculated thrust is based on the maximum differential pressure rating across the valve (as defined by ANSI) and not actual operating design conditions, the specified thrust might be much higher than actual, which would require a larger cylinder and thus a higher price. Therefore, it is best to specify thrust based on actual design conditions to get the best price.

Linear actuators can be an effective automation solution for gate valves. As automation increases, so should our choices. That the linear actuator has proven reliable in many applications outside of the valve industry is testament to the enduring design of the pneumatic and hydraulic cylinder.

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