05312016Tue
Last updateTue, 31 May 2016 7pm

i

The Limits of Standard Manual Globe Valves for Throttling

The Limits of Standard Manual Globe Valves for Throttling

A common practice in process services is...

Industry and Regulatory Changes in Offshore Operations

Industry and Regulatory Changes in Offshore Operations

On May 13, 2016, the offshore oil and ga...

Strategies for Successful SIS Valve Diagnostic Implementation

Strategies for Successful SIS Valve Diagnostic Implementation

End users and contractors alike strive t...

Stop Check Valves

Stop Check Valves

Stop check valves are vital to several i...

Subscribe

SUBSCRIBE

•  Digital magazine

•  Print magazine

•  VALVE eNews

Read the latest issue of VALVE Magazine

BUYERS GUIDE 300x220

New Products

  • ja-news-2
  • ja-news-3

Industry Headlines

Additive Manufacturing Industry Hit $5.1 Billion in 2015

2 HOURS AGO  |  Chris Guy

According to Wohlers Report 2016, the additive manufacturing (AM) industry, consisting of all AM products and services worldwide, grew 25.9% (CAGR) to...

Readmore

Loading...
Advertisement
i

Industry Headlines

Weir Opens New Safety Relief Valve Facility in Malaysia

1 DAY AGO

Weir has opened a new facility to increase the global reach and competitiveness of Weir valves by establishing a manufacturing and assembly plant close to Malaysia’s capital Kuala Lumpur.

The Malaysian operation has already successfully supplied several large and strategic projects, especially ...

Readmore

ValvTechnologies Names Garcia, Mermelstein to New Positions

6 DAYS AGO
ValvTechnologies Names Garcia, Mermelstein to New Positions

ValvTechnologies, Inc. has named David Garcia director of manufacturing and Steve Mermelstein as regional director, Americas and director, channel management.

Previously, West Point graduate Garcia served as director of operations for Merla Wellhead Solutions and held plant manager positions at Hallib...

Readmore

What’s Behind Growth of U.S. Natural Gas Use

2 HOURS AGO

U.S. consumption of natural gas is projected to rise from 28 trillion cubic feet (Tcf) in 2015 to 34 Tcf in 2040, an average increase of about 1% annually, according to EIA's Annual Energy Outlook 2016 . The industrial and electric power sectors make up 49% and 34% of this growth, respectively, while ...

Readmore

Industry Survey Finds U.S. Wind Power on the Rise

3 HOURS AGO

Wind power, America’s fastest growing new source of electricity, will stay on pace to grow to supply 10% of U.S. electricity by 2020, that’s according to the American Wind Energy Association (AWEA). Helping to grow wind energy in the U.S. are a mix of stable federal policy, passed late las...

Readmore

Additive Manufacturing Industry Hit $5.1 Billion in 2015

2 HOURS AGO

According to Wohlers Report 2016, the additive manufacturing (AM) industry, consisting of all AM products and services worldwide, grew 25.9% (CAGR) to $5.165 billion in 2015. The CAGR for the previous three years was 31.5%. Over the past 27 years, the CAGR for the industry is 26.2%. Wohlers Associat...

Readmore

Second Quarter GDP Forecast Points to 2.9% Increase

6 HOURS AGO

The Atlanta Federal Reserve’s GDPNow model forecast for real GDP growth in the second quarter of 2016 is 2.9% on May 26, up from 2.5% on May 17. The forecast for second-quarter real gross private domestic investment growth increased from -0.3% to 0.4% following this morning's durable manufacturi...

Readmore

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.

  • Latest Post

  • Popular

  • Links

  • Events

Advertisement

Looking for a career in the Valve Industry?

ValveCareers Horiz

To learn more, watch the videos below or visit ValveCareers.com a special initiative of the Valve Manufacturers Association