• induction loopsthat are buried under the pavement near the door. These are sensitive to the height of the vehicle chassis above the floor. For example, a sensor that is set to be triggered by a forklift truck may not be triggered by a tractor trailer.
• motion detectors. Ultrasonic motion detectors and photoelectric light beams are capable of restricting their sensing range to a localized area in front of the door. Other types of motion sensors, such as infrared units, are likely to be triggered by activities that are unrelated to the door.
• card access controls are used primarily for security against unauthorized entry. The driver inserts a card into a card reader to open the door, and a proximity sensor of some type closes the door after the vehicle passes through.
• time delay controls are used in combination with other controls to keep the door open for a minimum period of time. Time delays are used in applications that have heavy traffic, to reduce excessive cycling of doors.
If you install automatic or remote controls, consider installing an additional manual control at the door. This allows emergency exiting and provides backup if the automatic control fails. Decide whether your application makes it desirable
to stop the door at a partially open position. If so, provide controls that make this possible.
• induction loopsthat are buried under the pavement near the door. These are sensitive to the height of the vehicle chassis above the floor. For example, a sensor that is set to be triggered by a forklift truck may not be triggered by a tractor trailer.• motion detectors. Ultrasonic motion detectors and photoelectric light beams are capable of restricting their sensing range to a localized area in front of the door. Other types of motion sensors, such as infrared units, are likely to be triggered by activities that are unrelated to the door.• card access controls are used primarily for security against unauthorized entry. The driver inserts a card into a card reader to open the door, and a proximity sensor of some type closes the door after the vehicle passes through.• time delay controls are used in combination with other controls to keep the door open for a minimum period of time. Time delays are used in applications that have heavy traffic, to reduce excessive cycling of doors.If you install automatic or remote controls, consider installing an additional manual control at the door. This allows emergency exiting and provides backup if the automatic control fails. Decide whether your application makes it desirableto stop the door at a partially open position. If so, provide controls that make this possible.
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