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How to setup a Mantrap


How to setup a Mantrap


  • I/NET Access Control Site
  • Interlocked Doors
  • Person Trap
  • Anti-Passback (APB)


Site wants the more secure mantrap option


What is a mantrap? A mantrap is a security device that monitors and controls two or more interlocking doors to a small room that separates a non-secured area from a secured area. These interlocking doors allow only one door to be open at any time.

What are interlocking doors? “Interlocking doors” is a security term used to describe how two or more doors are interfaced with each other and locked. Doors that are interlocked cannot be open at the same time. Either door can be unlocked and opened as long as the other door is locked and closed, and no other alarm condition exists.

What types of locations require a mantrap? Mantraps are used at high value or critical security areas where only authorized persons are allowed to enter. Typical areas include sensitive data processing areas, cash handling areas, critical research labs, security control rooms, and automated airline passenger entry portals.

Why would my company consider a mantrap? Typically, security personnel are posted in high security locations to control access into the area. An automatic mantrap used in this same location would control the access to the area, allowing security personnel resources to be available for other tasks.

What is the difference between a mantrap and an interlocking door control system? When speaking of controlling two doors within a vestibule, “mantrap” and “interlocking door controller” can be used interchangeably. Once the number of doors controlled by a single controller exceeds two then the term interlocking door controller should be used.

I/NET has three ways to do a mantrap:

  1. Event sequences and calculations -- limit to 5-7 SCUs per 7798C due to system loading
  2. Use a "standalone" third party device that is wired to the door and is not attached to I/NET at all
  3. Use the interlock wiring diagram that uses relay logic to function. This is also part of the I/NET System.

I/NET Seven allows configuring a door to have both an entry and an exit reader and uses the selection of Anti-pass back/Anti-tailgate to set up Zones or areas with stricter control over access. However, even with the Anti-pass back option set to Hard which denies access to successive reads at the same reader, it does not prevent multiple persons from entering and exiting together and it does not provide real time accounting for the number of people in a Zone. Other than having a guard at the door the usual method of implementing Zones does not prevent violations. The example below presents some thoughts about how to improve the security of the Zone in an I/NET Seven system.

  1. There needs to be a way to restrict the number of people gaining access to the door.
  2. There needs to be a way to keep up with how many people are in the Zone.

One method to accomplish the first goal is to use a two door egress system as is often used in jails and similar security setups. For a medium security setup where the intent is not to prevent people from leaving only one of the doors needs to have a card reader. Such a design is illustrated below:


  1. Electric strike normally energized.
  2. Low walls or fences. The area should be small enough to limit how many people or things are in it at one time.
  3. Gate with normally de-energized bolt. The gate could swing both ways so one would only have to push it to open it. It should have a spring to close it.

The door “a” would have both an Entry and Exit reader so Anti-pass back/Anti-tailgate can be implemented. The strike on door “a” would be normally energized and be opened by a valid reader transaction.

The bolt on the gate would be normally de-energized allowing the gate to open freely. When the strike on door “a” is de-energized, the bolt on the gate would be energized preventing the gate from opening. This is designed to allow only one person to move into or out of the Zone at one time.

An added level of security would be accomplished by mounting IR emitter/receiver pairs along the low wall or fence at regular intervals. A person would interrupt the light at a limited number of receivers so if more than expected are interrupted it would be a violation of one person at a time and necessary action could be taken.

If material needed to be moved through the door the gated area could be made large enough to allow for a dolly or whatever might be needed. A different access level would be provided to those who are moving material thus preventing the alarm for too many people going through the door.

This approach would restrict movement into and out of the Zone and the example given in the AIC note could be implemented to allow real time monitoring of occupancy levels in the Zone.

Design thoughts:
To calculate whether more than one person is in the gated area, sum the number of receivers that are detecting and compare it to a minimum, e.g. four of six must be detecting if only one person is in the area.

If material is in the gated area generate an alarm if an authorized card is not read. Use the alarm delay for the point to give an individual time to make a card read before sounding the alarm.

The AIC scheme described in the AIC note would have to be duplicated for the material mover individuals to change the calculation of a person in the gated area. For material movers the detection would be (sum of detectors < minimum) whereas for regular individuals the detection would be (sum of detectors > minimum). Remember the SLI connected to this door can have only 64 AIC’s and this door now has used 2 of them

Use an inter-card delay long enough to let the person to get out of the gated area before another card can be read.

For personnel safety there must be a way to de-energize the strike. One method would be to mount an emergency exit button located far enough away from the door so a single person would not be able to reach it and a second emergency exit button on the outside of the Zone so someone could keep the strike de-energized until everyone is evacuated. Most codes probably require that all strikes be de-energized in case of smoke or similar emergency so that would provide another fail-safe.


Here is a pdf document which explains the setup using an SCU
Click here to download third party ManTrap information.

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‎2018-09-10 05:08 AM
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