When Regular Grilles Won't Do

February 11, 2005
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Standard metal registers and grilles can be used in many different residential and commercial applications. When it comes to high-risk applications, however, standard products just won't work. That's when contractors and engineers turn to manufacturers who produce security registers and grilles.

Security ventilation products are manufactured of heavier materials and welded construction and are available in minimum, medium, or maximum security configurations. Different styles are available to provide resistance to escape or vandalism, and several levels of suicide resistant grilles are also available.

As can be suspected, security products are often used in prisons and detention facilities. They cost more than standard products, and there is also an energy penalty associated with them, but when security is an issue, nothing but security registers and grilles will do.

Maximum security grilles, such as the one shown here by Nailor Industries, are usually constructed from 3/16-inch welded steel.

Why They're Different

Security registers and grilles are specially designed and fabricated to withstand abuse from people (prisoners) and animals (zoos). The materials are much heavier than standard commercial or residential grilles, and their configurations are sometimes different from standard products.

For example, some incorporate small holes or passageways that minimize the ability to hide contraband.

Maximum security grilles are usually constructed from 3/16-inch welded steel, medium security grilles are usually manufactured from 14-gauge steel or thicker, and minimum security grilles are basically made to be tamperproof. Areas that require maximum security grilles enable prisoners, for example, to be left unattended for longer periods of time, while constant supervision is usually employed in applications using minimum security grilles.

"Prisons, jail cells, and psychiatric wards are common places in which our security products are installed," said Duane Hotchkiss, manager of security products, KEES Inc., Elkhart Lake, Wis.

"Gymnasiums and schools sometimes also use security grilles or diffusers. These products are typically specified by an architect or engineer with the style selected for the specific application."

Prisons specifying security products expect them to be tamperproof, able to withstand force, and able to keep prisoners from escaping through the ductwork that makes up an air distribution system.

"Another important item is to keep anyone from ripping the grille out from its opening and using it, or a piece of it, as a weapon to harm themselves or others. And, of course, the grilles still have the job of distributing the air through the building," said Cindy Ross, marketing coordinator, Nailor Industries Inc.

Prison officials often worry about prisoners harming themselves, which is why there are several different types of suicide resistant products.

Some registers simply have smaller holes, so it's difficult to thread anything through them. Another generation of product has a V-blade in it so if something is threaded through it, it's almost impossible to pull back. The third group has a Z-shaped blade, which makes it virtually impossible to use the product in a suicide attempt. Hole sizes also vary within these groups of products.

Security registers and grilles are specially designed and fabricated to withstand abuse from people and animals. Different styles, such as the ones shown above and below by KEES Inc., are available for various types of applications.

Associated Costs

As already noted, security ventilation products can cost quite a bit more than standard products. One of the factors is the heavy gauge steel that is used, as it costs significantly more than the lighter gauges used in standard commercial products.

"The weight of the product is much heavier, which increases the handling costs," said Ross. "And the labor to produce the product becomes much more intense because of custom options and accessories that are available, as well as the welding and the extra care involved."

Hotchkiss estimates security registers and grilles can cost between three and 20 times that of a standard commercial grille depending on the required construction.

And while there really isn't a "bad" place to use security products, their higher cost, labor-intensive installation, and the additional energy consumed mean they probably shouldn't be recommended unless a need has been determined.

Pressure loss is one of the biggest drawbacks to using security products. The free area in a security register or grille is between 20 percent and 60 percent that of a commercial grille, and because of this, the pressure losses are much higher.

"I would guess that the energy penalty would probably be a minimum of 10 percent more than a standard grille, but I know of some that have had 10 times that amount in energy penalties," noted Hotchkiss. He suggested that system designers check the cataloged performance for the product selected to make sure the fan system is sufficient.

Additional labor is another reason why security products cost more. Maximum security grilles are typically installed by field welding or bolting an angle frame to the grille sleeve on the back side of the wall or ceiling.

Some minimum and medium security grilles and diffusers are mounted using tamper resistant screws. In addition, structural changes may be required, as is the case with one style of 12- by 12-inch grille that weighs 125 pounds. All these factors add time to the job.

Because of the smaller free area, security registers and grilles have sound levels that may be considerably higher than standard commercial grilles. One solution, noted Hotchkiss, is to make the grille larger.

"By making it larger, you increase the total amount of face area that the air has to pass through, which will reduce the velocities and reduce the sound. However, sound control isn't usually a major issue in prisons, as they're pretty noisy places."

The installation will dictate the type of cleaning needed for the security grilles or registers. Many can be wiped down with a wet cloth, but prisoners in cells with 24-hour-a-day access can wreak havoc with a finish.

In these cases, painted grilles may need to be sanded and repainted. Grilles with small holes may require wire brushing to keep the holes open. To make it easier for themselves, some facilities specify stainless steel construction so they can be steam cleaned.

If aesthetics are an issue, Hotchkiss noted that they can accommodate many different requests. "We have furnished an aquarium with oval shaped security grilles that were mounted in a door, as the architect was trying to establish the feel of being in a submarine."

He added security grilles and diffusers can be fabricated of stainless steel with a brushed finish for use in hospitals. Custom paint colors are also not uncommon, especially when they're specified for their soothing qualities.

No matter what the high-risk application, chances are there's a security product out there that's a perfect match for it.

Publication date: 02/14/2005

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