SVL News
Accutrol: The Technological Revolution in Critical Airflow
New technologies are being deployed in facets of HVAC that would have been nearly unimaginable 20 years ago. We sat down with Victor Cincola from Accutrol, LLC at our latest Coffee Break webinar for an overview of how AccuValve is changing airflow systems.
SVL Coffee Breaks are 45-minute presentations from the leading innovators in the HVAC community. To stay up to speed on the latest developments in the industry, contact your SVL Sales Engineer for an invite to our upcoming sessions.
What are the traditional methods for airflow control?
There have historically been two basic technologies that are used to control the airflow to a space. Both have their pros and cons and applications to which they are best suited.
The first and most basic one of these technologies is a box with a single-blade damper and differential pressure airflow measurement. This is the basic setup you’ll find in VAV boxes. It is still a good choice for office environments because it’s economical and the space usually doesn’t experience large swings in airflow demand. That’s important because one of the significant limitations is that boxes like these are not linear devices, meaning they perform best at the high end of their specified airflow range.
The second technology is a mechanical Venturi valve. This was a preferred solution from the 1980s to the 2000s. It contains no airflow measurement because the airflow going through it is metered. As static pressure changes, the valve mechanically compensates to maintain the design cfm.
Are these technologies out of date?
No. There’s no one-size-fits-all solution in airflow and both technologies continue to be used successfully today. However, there have been technological advancements in this facet of HVAC that allow, for example, for greater control at lower static pressures and greater flexibility of placement and orientation.
Accutrol has seen the desire for energy efficiency and flexibility in airflow control. Owners want to run their systems at lower pressure, with less fan horsepower, while accurately measuring airflow in the system.
Accutrol’s AccuValve® with VorTek™ airflow measurement is the new alternative. What makes it different?
AccuValve is designed to deliver accurate airflow at a low pressure drop. This has a cascading effect — lower pressure means lower energy usage, not having to run fans so hard means less fan maintenance and longer service life, and ultimately, smaller fans and improved acoustics.
The valve also delivers precise, true airflow measurements without the need for a straight run. To measure airflow, you need a developed, repeatable airflow profile over the range you want to operate in. Straight runs are commonly used to accomplish this, but there are other ways. Compression is another.
No matter how the airflow comes into the AccuValve, the airflow is compressed into two sections and the airflow is fully developed at the flow sensor locations. It doesn’t matter how the valve is mounted or oriented, or if airflow is greater in one section. The measurements are measured in the two chambers separately and added together.
Then a set of control blades in one or both sections can restrict the amount of airflow going through the valve. Finally, a regain section at the end of the valve allows the airflow to decompress in an organized fashion, making the valve much more efficient.
Are the control blades on AccuValve any different than those of a single-blade damper?
The control blades on the AccuValve open and close at a different rate. This is why the airflow is measured in two chambers, because there may be times when the control blades create greater flow through one side and less through the other. The mechanical reason for this is to create a much more linear control in terms of flow through the valve and its position.
The idea is similar, although not entirely the same, to a two-thirds/one-third liquid valve that linearizes the flow through the valve.
AccuValve’s airflow sensing and the offset blades give the valve a large turndown, at least 10:1, sometimes even more, of excellent, linear airflow control. This means you don’t have to know the exact range in which you apply the valve. This is especially nice if you’re retrofitting a building and replacing mechanical Venturi valves. When you finally dial back the static pressure in the system, you won’t have to go back and recalibrate all the valves to compensate for the change in pressure.