Louvers 101

A louver is a simple air system component that allows the passage of air from one side of a vertical opening in a wall, plenum, or bulkhead to the other side of the opening, while at the same time, depend on its design, prevents water, dust, or sand from traveling through the opening.  Below is the Louvers 101 class on the basics of louvers and louver technology.

BASICS

Louvers used on the intake side of an air system are called intake louvers. Likewise, louvers used on the exhaust side of an air system are called exhaust louvers.

Louvers fall into two basic categories:

  • Architectural/Commercial Louvers (like what you see on a building)
  • Industrial/Marine Louvers (like what is required for more robust applications)

At Eldridge, we specialize in working with industrial/marine louvers.

A louver has either stationary or adjustable blades that are mounted in a frame having two vertical sides (jambs), one horizontal top piece (head), and one horizontal bottom piece (sill). Intermediate vertical pieces (mullions) are sometimes located between the jambs when the louver becomes exceedingly wide.

A louver can come in any size or shape. For a square or rectangular louver, its size is always specified Width x Height x Depth in inches (or millimeters). The Width is the dimension that is parallel to the horizontal head and sill of the louver.

Industrial/marine louvers are normally fabricated out of extruded aluminum with an anodized finish, hot rolled steel (painted), galvanized steel, or stainless steel, depending on the application.

STATIONARY LOUVERS

A stationary louver has blades that are always held in a fixed position. The blades are welded or fastened into the frame at an angle so that water can drain off the blades properly. Blades fixed at a 45° or 30° angle are very common stationary louver configurations.

ADJUSTABLE LOUVERS

An adjustable louver has blades that can be opened or closed either manually or mechanically with an electric or pneumatic actuator. This type of louver is used when the opening needs to be closed up to provide a more positive rain barrier or to conserve internal heat, like in the winter, for example. Typically blade and jamb seals are provided on an adjustable louver to provide a tighter seal when closed.

MODERN LOUVER TECHNOLOGY

Advancements in design and technology have also created some very interesting variations of louvers. For example, there is a horizontal drainable blade louver, which has small gutters on the lower horizontal blade edges that divert rainwater to downspouts in the jambs. This creates a more rainproof louver while maintaining the traditional horizontal blade appearance.

Another louver advancement is the acoustic louver, which combines the features of a typical horizontal blade louver with noise reduction treatments. Acoustic louvers come in both stationary and adjustable configurations. However, acoustic louvers can become very large and heavy due to the acoustic treatments required. The acoustic treatments add additional backpressure to the airflow, which often requires a larger louver to be used. An acoustic louver with a chevron blade design and noise reduction treatment provides a complete “line of sight” blockage to create an air pass direction change and maximum noise reduction on critical applications.

Eldridge is also a leader in modern louver technology. The Eldridge Vertical Storm Louver with all welded anodized, extruded aluminum construction was created for use in our US patented Eldridge Storm Guard Hoods. The blades in the Eldridge Vertical Storm Louver are situated vertically instead of horizontally. The blades of a 6” deep Eldridge Vertical Storm Louver are spaced close together and have internal features that prevent 99.9% of the rain falling at a rate of 14” per hour with a 50 MPH wind from getting through it. We can even remove rainfall of 30” per hour at 110 mph wind speed with our 12” deep model!

The Eldridge Vertical Storm Louver is used in critical air systems and environments where any amount of rain that gets through the louver could create an electrical shock hazard to personnel or possibly destroy the equipment it protects. This is true of transformer rooms, engine-generator rooms, air compressor rooms, electrical switchgear rooms, and even some large electrical motors. The Eldridge Vertical Storm Louver is so effective that it can also be used as a sand louver to remove airborne dust/sand in a number of critical applications.

In addition to the sizing convention, rain entrainment, noise reduction, or dust elimination requirements mentioned above, there are other specification details required to properly select the louver that is right for the job. These specification details include airflow volume, air velocity, pressure drop criteria, and geometry of the louver.

We hope that our Louvers 101 class gave you a better understanding of what is available and that our Louvers 101 class will help you make good decisions when selecting louvers.  Sometimes, there is a tendency sometimes to confuse Louvers with Dampers. To learn more about dampers, read this article.