Portable Door Sensor Alarm: A Comprehensive Guide

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A portable door sensor alarm is a security device designed to detect unauthorized entry through a door. It typically consists of a sensor that is attached to the door or door frame and an alarm unit that is triggered when the sensor is activated. The sensor can be a magnetic contact sensor, which is activated when the door is opened, or a pressure sensor, which is activated when weight is applied to the door.

Types of Portable Door Sensor Alarms

Magnetic Contact Sensors

Magnetic contact sensors are the most common type of sensor used in portable door sensor alarms. These sensors consist of two components: a magnet and a reed switch. The magnet is attached to the door, and the reed switch is attached to the door frame. When the door is closed, the magnet and reed switch are in close proximity, and the circuit is complete. When the door is opened, the magnet and reed switch are separated, and the circuit is broken, triggering the alarm.

Magnetic contact sensors are highly reliable and can be easily installed. They are typically rated for a maximum door gap of 1 inch (25 mm) and can withstand a maximum door opening force of 40 lbs (18 kg). These sensors are available in a variety of sizes and styles to fit different door types and configurations.

Pressure Sensors

Pressure sensors are another type of sensor used in portable door sensor alarms. These sensors are designed to detect changes in pressure on the door, such as when someone applies weight to the door. Pressure sensors can be installed on the door or the door frame and are typically more sensitive than magnetic contact sensors.

Pressure sensors are often used in applications where the door may be opened slowly or where the door may be propped open. They can detect even the slightest changes in pressure and can trigger the alarm accordingly. Pressure sensors are typically rated for a maximum pressure of 10 lbs/in² (69 kPa) and can withstand a maximum door opening force of 50 lbs (23 kg).

Microwave Sensors

Interior microwave sensors are another type of sensor that can be used in a portable door sensor alarm. These sensors emit an energy field and detect changes in the field caused by motion within the protected area. They typically operate in the X band radiofrequency region (7 to 11 gigahertz) and can detect motion through walls and other obstacles.

Microwave sensors are highly sensitive and can detect even the slightest movements within the protected area. They are often used in applications where the door may be opened slowly or where the door may be propped open. Microwave sensors are typically rated for a maximum detection range of 50 ft (15 m) and can withstand a maximum door opening force of 60 lbs (27 kg).

Technical Specifications of Portable Door Sensor Alarms

portable door sensor alarm

Sensor Specifications

  • Magnetic contact sensors: Maximum door gap of 1 inch (25 mm), maximum door opening force of 40 lbs (18 kg)
  • Pressure sensors: Maximum pressure of 10 lbs/in² (69 kPa), maximum door opening force of 50 lbs (23 kg)
  • Microwave sensors: Maximum detection range of 50 ft (15 m), maximum door opening force of 60 lbs (27 kg)

Alarm Unit Specifications

  • Alarm output: 85-100 dB at 1 m
  • Power supply: 9-12 VDC, 500 mA
  • Battery backup: 4-6 hours of continuous operation
  • Dimensions: 5 x 3 x 1.5 inches (127 x 76 x 38 mm)
  • Weight: 8 oz (227 g)

Communication Specifications

  • Alarm communication: Wired or wireless (433 MHz or 915 MHz)
  • Alarm response time: Less than 2 seconds
  • Tamper detection: Enclosure and sensor tamper detection

Maintenance and Verification

The BMS (Building Management System) described in the reference materials includes a maintenance schedule with verification tasks that should be performed every 6 months. These tasks include:

  • Verifying tamper operation by accessing electronics enclosures and disconnecting communicating links of the sensors
  • Verifying tamper operation or alarm when a foreign magnetic field is introduced to the sensor
  • Verifying that an alarm occurs within a specific door movement distance
  • Verifying that no alarms occur during any slight movement of the door when it is latched
  • Verifying acceptable conditions of electrical power and communication lines

Cost and Installation Considerations

The cost of a portable door sensor alarm will depend on the type and number of sensors used, as well as the features and capabilities of the alarm unit. Typically, a basic system with a single magnetic contact sensor and an alarm unit can cost between $50 and $100. More advanced systems with multiple sensors and additional features can cost upwards of $300 or more.

The installation of a portable door sensor alarm can also vary in complexity depending on the specific requirements of the application. In some cases, the system can be easily installed by the end-user, while in other cases, professional installation may be required. The installation schedule will depend on the availability of the necessary equipment and personnel.

Conclusion

Portable door sensor alarms are a valuable security device that can provide early warning of unauthorized entry. When selecting a door sensor alarm, it is important to consider the technical specifications, cost, and installation requirements of the device. By understanding the different types of sensors and their capabilities, as well as the maintenance and verification requirements, users can ensure that their portable door sensor alarm system is effective and reliable.

References

  1. ADS-51-HDBK, “ADS-51 Helicopter Design Handbook,” 1996-10-21.
  2. NUREG-1959, “Intrusion Detection Systems and Subsystems,” 2011-11-01.
  3. FRA Office of Research, Development, and Technology, “2022 Research and Development Technical Projects,” 2021-12-10.