Sensorship That Makes Sense

Just as every person tries to find their true compatibility match, security experts are faced with the daily challenge of finding the correct alarm sensor for a specific security application. The range of technology selections is vast and can include both old and/or new technology. Experienced integrators have learned that while the latest technologies are new and exciting, keeping the product application simple yet efficient can often lead to the best technology match. With the popular use of wide-area security sensors such as the ever popular passive infrared (PIR) detector, it is easy for the security expert to overlook the many niche application detectors that, when applied properly, can fill in those little gaps in their overall security model.

It is often easy to catch people walking through open areas, but how does one effectively protect property along the fringe areas, or detect those criminals who slink up and over walls and rooftops? How can one protect against the tampering of objects? How can those little leaks be   tightened up in the security dam?

What follows is an examination of a large variety of security intrusion sensors. Some are new, some are old, and some you may not have even heard of before. The goal is to come away with a larger bag of tricks and techniques to help foil even the most devious of criminals. 

Techniques Used to Protect High-Security Rooms and Vaults

What are some ways to detect intrusion at the perimeter of a room? Some of the obvious are magnetic proximity reed switch sensors/contacts for doors and windows, both standard and balanced for high security. Make sure to select the right type of contact for metal frames and plenty of air gap tolerance to reduce false   alarms and achieve proper sensitivity.

There is a new type of magnetic contact on the market called the “Magnasphere.” It uses a small conductive ball in a miniature spherical enclosure that, when influenced by a nearby magnet, creates a unique configuration that will keep even sophisticated criminals at bay.

One old technique that is still being used for protecting the penetration of walls and doors is the art of lacing. This can either be done with fine wire or foil strips. The fine conductors are installed in a grid configuration, allowing the barriers to have a lining. Any opening small enough for a person to fit through will be detected. UL security certification requires that an opening greater than 96 inches — with the smallest dimension not exceeding six inches — be detected.  When the lacing surface is covered, there is no indication that this type of security has been applied to the barrier. This lacing technique is also used with specially designed window screens and doors for complete coverage of an opening.

For high-security rooms and vaults, another intrusion device is the seismic sensor. Devices such as the Bosch ISN-SM Series and the Honeywell UN3 come with microphones and digital signal processors (DSPs), and work well on concrete and steel reinforced vaults. However, if you are looking to provide cost-effective protection from drilling and tampering of metal equipment enclosures, then GE Security makes a nice little sensor, Model 5402 shock sensor.  Another interesting method to inconspicuously detect the movement of personnel is the use of stress detectors, or as engineers call them, strain gauge detectors. This is a device that can detect the extra stress placed on a roof or floor support beam when a person walks on it.

Sure Action of Hampton Bays, N.Y., is one manufacturer that offers such a device. The company’s, Pulsor sensor can be fastened to prepared supports and then analyze the pulses of people walking on the structure. Some other interesting areas of application might include steel fire escapes, under window sills and stairways, tractor trailer beds, marine   craft decks and chain-link fence posts.

Object Removal Triggers Electrically-Supervised Alarm Circuit

A challenging area for alarm sensors is detecting the removal of valuable objects within an overall active, yet unprotected, area. This might include items such as office or construction equipment. To protect these items, a good sensor configuration is the GE Security 2100 Series “Magnapull” pull-apart cord.  This device provides an electrically-supervised alarm circuit allowing equipment to move, but not to be removed without triggering an alarm.

A very good source for the security professional when reviewing various security intrusion sensor applications is the newly revised 192-page GE Security “Intrusion Sensors Application Handbook,” which is now available as a free download to security professionals at This book is a must for a security practitioner’s library. 

Shock, Acoustic Sensors Discern Glass-Breaking Sound Waves

In olden days, window glass was mainly protected by applying thin strips of conductive foil that upon being broken would activate the alarm. However, today window glass is protected by a variety of specially designed shock sensors. These sensors mainly have two categories: sensor modules that mount directly to the glass or glass mounting frame, and acoustical glass-break detectors that “listen” for the sound signature of breaking glass.

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