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Introduction to Automatic Gates
Automatic gates are used to control access into a secured area. Most commonly, automatic gates are used at the entrance to the facility, and are used to control vehicular access on and off of the site. For example, a manufacturing plant may use an automatic gate at its main entrance. All vehicles entering and exiting the plant must do so through the automatic gate. Automatic gates are also used at interior areas within a facility. For example, automatic gates are commonly used within the inside of a parking garage to separate employee parking areas from public areas of the garage.
Components of an Automatic Gate
Automatic gates consist of two basic components:
Types of Automatic Gates
There are six types of commonly used automatic gates. These include the slide gate, cantilever gate, swing gate, vertical lift gate, vertical pivot lift gate, bi-folding gate, and barrier arm gate. The following is a brief description of each type of gate:
The slide gate is probably the most commonly used type of automatic gate in light-duty commercial applications.
The slide gate is mounted parallel to the inside of the fence and slides horizontally back and forth across the gate opening. The slide gate uses rollers on the bottom of the gate to support it. These rollers typically ride along a metal track that has been installed along the ground across the gate opening. Slide gates are sometime also called "rolling gates" or "V-track gates".
Because this type of gate uses rollers that must run along the ground, there can be problems with the rollers getting blocked by snow, ice, or debris. The rollers can also be a source of friction, making the gate operator have to work harder to open and close the gate. Due to these issues, some gate operator manufacturers discourage the use of slide gates.
The cantilever gate is similar to the slide gate, but does not use rollers that slide along the ground to support it. Instead, the cantilever gate is supported from rails that run along the inside of the fence structure. This gate gets its name from the fact that the gate "cantilevers" (hangs over) the gate opening. Cantilever gates need to be much wider than slide gates in order to provide a section along the fence structure where the gate is supported. This section is called a "counterbalance" and is usually at least 1/2 the width of the gate opening itself
Cantilever gates are suspended across the gate opening from the counterbalance, with no rollers running along the ground to provide friction or to become obstructed. Because of this, cantilever gates are considered to be much more reliable than slide gates, and are commonly used for heavy-duty and industrial gate applications.
One downside to using cantilever gates is the additional width required to accommodate the counterbalance. This can be a problem at sites that have limited space available beside the gate.
Swing gates are hinged on one side and swing open and closed like a door. Swing gates typically travel a 90 degree arc between their open and closed positions. Swing gates can consist of a single leaf or double leafs and can be in-swinging or out-swinging.
Swing gates are most commonly used in residential applications because of their low cost and ease of installation. Because swing gates travel over a large arc, space must be available to allow vehicles approaching the gate to remain clear while the gate opens or closes. The swinging arc of the gate also requires additional safety considerations to prevent people or vehicles from being hit or trapped by the moving gate.
Vertical Lift Gate
Vertical lift gates move up and down vertically over the gate opening. The gate must be lifted high enough to allow vehicles to pass underneath of it. This type of gate requires that tall vertical support towers be installed on each side of the gate opening.
Vertical lift gates are ideal when there is limited space available next to the gate opening. Vertical lift gates are also very fast and very reliable. The appearance of the vertical support towers gives these gates a very "industrial" appearance, which may make them unsuitable for use in locations where appearance is important.
Vertical Pivot Lift Gate
Vertical pivot lift gates rotate in and out of the gate opening. Vertical pivot lift gates are supported entirely from the gate operator itself and do not require any additional support structures.
Vertical pivot lift gates provide some of the benefits of vertical lift gates, but appear less obtrusive as they do not require vertical support towers. However, the footprint of a vertical pivot lift gate operator is larger and requires additional space beside the gate. Vertical pivot lift operators typically use springs to serve as a counterweight, and in our opinion, this makes them less reliable than a standard vertical lift gate.
Bi-folding gates consist of two gate panels that are hinged together. When activated, these gate panels fold back onto themselves to allow access. Most commonly, bi-folding gates are used in pairs, with one pair being used on each side of the gate opening. Some models require a track along either the top or bottom of the gate.
Bi-folding gates require only a small footprint and are often a good choice when space is limited. Many bi-folding gates have relatively fast opening and closing speeds. Because of the many potential entrapment points possible with this type of gate, additional safety considerations are often required.
Barrier Arm Gate
Barrier arm gates consist of a vertical barrier arm that is rotated in and out of the gate opening. Barrier arm gates are used to control vehicles, not pedestrians. As it is very easy for a person to walk beside or climb over or under the gate arm, barrier arm gates provide almost no security.
Barrier arm gates are used primarily to control access in and out of parking facilities, or to control vehicular traffic at manned security entrances.
Automatic Gate Accessories
There are many accessories that may be used in conjunction with automatic gates. Some of these include:
Gate Safety Devices
Automatic gates can weigh as much as 20,000 pounds or more and can travel at speeds as high as 36 inches per second or faster. As a result, gates have the potential to cause serious property damage, injury or death. Therefore, it is extremely important that safety considerations be included when planning any type of automatic gate installation.
The primary guideline for automatic gate safety is Underwriters Laboratories (UL) Standard 325. This standard defines classes of automatic gate operators and the various techniques that should be used to prevent entrapment and reduce the potential for injury. Gate safety measures can include warning signage, audible warning devices, photoelectric sensors, contact (pressure) sensors, screening, safety cages, and other devices.
Because some of the requirements of UL 325 are difficult and costly to implement, many gate installers have chosen to downplay or ignore these requirements. It is often easy to get away with this because there is little enforcement of these standards in many parts of the country. However, the property owner who installs an automatic gate that is in violation of recognized standards does so at his own peril and may be held liable if someone is injured by the gate.
Considerations When Choosing an Automatic Gate
The following are some basic things that must be considered when choosing an automatic gate:
Deciding which type of automatic gate to use is a big decision. Automatic gates are expensive to install and require regular ongoing maintenance. Sometimes, purchasing a more expensive gate initially can actually save you money over the long-run due to reduced maintenance costs. Many architects and builders will specify the cheapest gate possible when the facility is being built. The property owner then has to live with the consequences, which can include frequent downtime and costly repairs.
If you are not sure what type of gate or gate operator to use, it is recommended that you retain the services of a professional engineer or independent security consultant to help you assess your needs and to select the correct product.
If you need help in selecting and specifying an automatic gate for your facility, or if you simply have questions, please contact us.
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