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Food and Beverage Processing

Food and Beverage Processing

When wandering the grocery store aisles,...

Variable Frequency Drives in Electric Actuators

Variable Frequency Drives in Electric Actuators

Electric actuators are vital for operati...

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Industry Headlines

Food and Beverage Sales Strongest in Four Years

11 HOURS AGO  |  Chris Guy

The U.S. consumer packaged goods (CPG) industry registered its strongest growth in four years in 2015, and some of the biggest gains were achieved by ...

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Industry Headlines

A.W. Chesterton Expands Training and Services Facility

17 HOURS AGO

A.W. Chesterton Company has expanded its facilities north of Boston with a new valve emissions testing facility, an expansive industrial training center and an industrial equipment service location to support its New England‐based customers.

The New England Service Center expansion provides mechanical...

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Spirax Sarco Supporting the Enbridge Ride to Conquer Cancer

1 DAY AGO

Spirax Sarco USA is teaming up with Spirax Sarco Canada for the Enbridge Ride to Conquer Cancer. From June 11-12, 2016, participants will cycle 200 km with thousands of other men and women throughout the countryside of Ontario, Canada. All net proceeds will benefit Princess Margaret Cancer Centre.

Th...

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Food and Beverage Sales Strongest in Four Years

11 HOURS AGO

The U.S. consumer packaged goods (CPG) industry registered its strongest growth in four years in 2015, and some of the biggest gains were achieved by companies targeting the fast-growing market for protein-rich foods and healthy, “mindful” snacks. These are among the findings of new resea...

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G7 Countries Vow to Support Energy Investments

1 DAY AGO

Leaders from Canada, France, Germany, Italy, Japan the UK and the U.S. have pledged to “promote investing in energy projects through the oil price crash to ensure a steady stream of supply” and “encourage financial institutions to invest in energy projects and infrastructure,&rdquo...

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Factory Orders in the U.S. Increased in March

17 HOURS AGO

New orders for factory goods rose 1.1% in March after falling a revised 1.9% in February, thanks largely to an increase in demand for defense equipment, the Commerce Department reports. This March increase in new orders was higher than the 0.6% rise economists predicted.

Durable-goods orders rose 0.8%,...

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U.S. Economy Grew 0.5% in First Quarter

2 DAYS AGO

U.S. GDP increased at an annual rate of 0.5% in the first quarter of 2016, according to the advance estimate released by the Bureau of Economic Analysis. In the fourth quarter, real GDP increased 1.4%.

The increase in real GDP in the first quarter reflected positive contributions from personal consumpt...

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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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