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CIRCOR Announces Availability of Historical Segment Information

-1 DAYS AGO

CIRCOR International announced the availability of certain historical segment information reflecting its previously announced organizational realignment beginning in the fourth quarter of 2016.

The new “Energy” segment, including the recent acquisition of Critical Flow Solutions, will prima...

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Curtiss-Wright, Clarke Industrial Engineering Sign Licensing Agreement

-1 DAYS AGO

Clarke Industrial Engineering has entered into a licensing agreement with Curtiss-Wright Corporation, whereby Clarke’s patented and proprietary Shutter Valve technology will be exclusively available to Curtiss-Wright for the worldwide naval defense market, the U.S. maritime homeland security mar...

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New Investments Spur Permian Oil Production Increase

3 HOURS AGO

The Department of Energy (DOE) said on Tuesday that oil production in the Permian Basin could increase by 53,000 bpd by next month. According to the Energy Information Administration (EIA), that is the largest monthly increase in the region in a year.

“The EIA’s first shale oil forecast o...

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Why is Oil & Gas Slow to Adopt Cloud Technology?

1 DAY AGO

“There are endless benefits to implementing a cloud-based system, many of which center around less waste and less hassle, but due to operational characteristics, oil & gas companies stand to benefit more than most.”

“Yet, while being among the sectors that stand to gain most fro...

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Industrial Production Sees Largest Rise in More Than Two Years

3 HOURS AGO

Industrial production rose 0.8% in December, the largest increase since November 2014, after falling 0.7% the previous month. For the fourth quarter as a whole, the index slipped 0.6% at an annual rate.

Manufacturing output moved up 0.2% in December, as an increase in durable manufacturing outweighed d...

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IMF Raises U.S. Economic Growth Forecast

1 DAY AGO

After a lackluster outturn in 2016, economic activity is projected to pick up pace in 2017 and 2018, especially in emerging market and developing economies. However, the International Monetary Fund (IMF) noted in its new World Economic Outlook, there is a wide dispersion of possible outcomes around ...

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Water Hammer—Check It Out

Have you ever been in an area of the plant that had just shut down a pump, only to hear an explosive sound a few seconds later? The noise you heard was the pump check valve, accompanied by the water hammer, or reverse flow, that slammed it shut.

Multiple pump systems often use a check valve located between the pump and the discharge header. The purpose of this valve is to prevent backflow from the header to the pump when it is not running. Without the check valve the pump could actually spin backwards.

Depending on the system pressure, these valves can close with such force that they damage the check valve, the pump, and over time even the pump base. Most check valves require reverse flow to close the valve and once this flow momentum has started, it does not stop as quickly as the check valve closes. The result is water hammer, a very destructive force. According to Webster's: Water hammer: a concussion, or sound of concussion, of moving water against the sides of a containing pipe or vessel.

We have seen many plants overcome these laws of physics with the use of an "auto check," also known as a "butterfly check." This concept utilizes a pneumatic-operated butterfly valve, and relatively simple control logic in order to close the valve automatically, prior to shutting down the pump. This action avoids reverse flow, so that the back flow and water hammer never have the chance to develop.

The valves for these applications are typically high-performance butterfly valves with a pneumatic actuator. Accessories include a limit switch and four-way pilot solenoid with two adjustable speed controls. The speed controls restrict the airflow out of the cylinder in both directions, thus regulating the opening and closing speed of the valve.

Control logic for the auto check is simple. When the pump is not pumping, the butterfly valve is closed. When the motor start command is received, either locally or from the PLC, the pump motor is energized. Pressure builds up on the pump side of the auto check valve. A differential pressure switch senses pressure differential between the newly started pump and the header past the auto check. At some predetermined point-such as 1 psi, .5 psi. or .25 psi-the delta p switch makes contact on pressure increase. The switch is sealed in by a relay and energizes the solenoid valve, which opens the butterfly valve smoothly, aided in part by the speed control valves. When the butterfly valve is totally open, a limit switch is tripped and sends a valve-open status to the PLC.

When the motor stop command is received, the pilot solenoid is de-energized and the valve closes at a controlled rate, again aided by the speed controls. When the valve is completely closed the limit switch is tripped, which in turn shuts off the pump motor. This action eliminates water hammer by preventing any back flow from occurring.

BRUCE FENWICK is in technical sales for McJunkin Corporation, Harvey IL. Reach him via 708.225.3120 or at This email address is being protected from spambots. You need JavaScript enabled to view it..

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