February 2010
Volume XVI, No. 2
Achieving Energy Savings Via Variable-Frequency Drives

Proactive Energy Management
Using Variable-Speed Drives to Maximize Pumping Efficiency
Whether it’s a small five horsepower motor for a chemical-feed pump, or a massive 1,000 hp counterpart for influent pumping in a water and wastewater treatment facility, electricity is needed to power the motors that operate the pumps that move the liquid as necessary. This fact can create challenges for facility owners and managers, who must balance steadily increasing utility rates with the need to cut costs in a sluggish economy. The good news is that pumps can be a key target for increased energy efficiency, as the latest generation of variable frequency drives (VFDs) enable an active energy management approach.

Gas Flow Check Metering
Benefits of Pipe Waveguide Method for Clamp-On Ultrasonic Flowmeters
Gas and oil are different in their physical, chemical, and ultrasonic properties. Nevertheless, each fluid state can benefit from new technology that uses a pipe wall as a sonic waveguide for accurate, repeatable, and reliable non-intrusive flow measurement. The following article explains how clamp-on ultrasonic flowmeters featuring such technology can be used to provide highly accurate check metering.

Q&A: Condition-Based Maintenance
How Predictive Strategies Can Effectively Limit Downtime
Eduardo Ballina has more than 25 years experience in automation and instrumentation, including motion control, robotics, CNC controllers, PLCs, laser measurement and vision systems and holds a degree in mechanical-electrical engineering from the Universidad Nacional Autónoma de México. Currently, Mr. Ballina has been with Invensys Operations Management since 1996 and currently manages the company’s water and wastewater business. Here, Mr. Ballina fields questions from Flow Control on condition-based maintenance strategies.

Control Valve Actuators
Key Considerations for Effective Technology Selection
The control valve, typically outfitted with an actuator, provides the final control element in many process systems. The actuator accepts a signal from an external source and, in response, positions (opens or closes) the valve to the required or designed position. Valve actuators enable remote operation of control valves, which is essential for worker safety in many application environments.

mailbag: Pump Problems
Questions On the Affinity Laws & Pump Discharge Pressure
I have a question regarding the Affinity Laws. Once you alter the velocity or impeller diameter of a centrifugal pump, how do you determine the new best efficiency of the altered pump? Cheers from Peru. I have a question regarding a fuel pump that fills holding tanks. The pump moves fuel into at least one holding tank. And sometimes this pump feeds up to four tanks, depending on the demand.

Flowmeter Turndown Overkill
Is 1,000-to-1 Really Better Than 100-to-1?
It would be fair to say that the overwhelming majority of instrument suppliers make valid claims about the instruments they sell. For example, a supplier may claim that its flowmeters perform within a specified accuracy, such as 0.5 percent of flowrate. The supplier has presumably tested the flowmeter and found that its performance falls within this specification. The user can then decide whether this particular flowmeter meets the needs of the application. Farther along in the conversation, the supplier may mention that the flowmeter has a turndown of 1000-to-1. Again, the claim may be factual and supported by test data. But, you should think about what 1000-to-1 turndown really means.

VIEWPOINT:
The State of Quality & Integrity
As I sit down to write this editorial, it is the morning after President Barack Obama’s first State of the Union address. And, as expected, the president delivered a speech that touched on all of the hot-button issues of the day – economic stimulus, healthcare, Wall Street, education, national security, etc. Likewise, Virginia Gov. Robert F. McDonnell, who delivered the Republican response to the State of the Union, issued a strong call for improvements on all of these fronts as well. Nevertheless, on many of the issues, the two disagreed on the path to a successful end. So, I, like many Americans I’d imagine, am left feeling frustrated, looking for signs of hope that we can come together to solve the problems currently confronting our country.