Security Interlock / Man-Trap

[LGreene]

Do any of you have experience with security interlocks (aka mantraps)? It's a series of two doors that creates a vestibule. Only one door can be opened at a time - either for security or to create an airlock leading to a clean room.

It can create an egress issue because if the outer door is held open, the inner door won't unlock to allow egress. I haven't been able to find any code language that addresses interlocks, but I see them quite often in lab areas and occasionally in retail (jewelry stores). Electromagnetic locks are typically used to create the interlock, but applying the access-controlled egress doors section of the code obviously defeats the purpose of the interlock.

There are things that can be done to make this application safer, like a) limit the use to certain occupancies, like a lab that is occupied by "trained traffic," b) unlock both doors upon fire alarm, c) provide an emergency override button inside the lab, d) in the case of a jewelry store, require a guard stationed at the door.

What's the protocol in your area and is there any code language to support it? I did a post about interlocks on my blog a while back, and a fire marshal just asked me a question so I thought I'd run it by you all. Here's a link to the post, which includes a video of how an interlock works: http://www.ihatehardware.com/2010/03/interlocks/

 

[cda]

You are throwing to many varibles at us, we can only handle one at a time.

Normal answer is you have to be able to get out with what ever method code allows

yes have seen various man traps, most in might city you can get out with no problem, do not care of getting into the building.

would have to see case by case set up to see if it meets code.

great answer MAYBE

 

[Builder Bob]

Also Banks are using mantraps to electronically trap people in buildings when bank robberies occur - original concept used the vestibule to isolate the robeer as they left, newer design appear to lock all doors - trapping everyody in the building. (This is hearsay from another person whose word I put alot of faith in.)

 

[Coug Dad]

In a correctional facility we generally call them "sally ports". Only one door can be open at a time. A guard must attend the doors at all times.

In a laboratory it would be delayed egress. The code allows delayed egress under serveral conditions.

I have dealt with two truly locked egress conditions in my career. One was for a quasi federal agency that deals in large amounts of cash. They had dead man switches that even over rode the fire alarm system.

The other was in a lab that if the bad stuff escaped, no one was getting out of the room.

In general though, your answers are in the code depending upon the occupancy.

 

[Coug Dad]

Hospitals are also using automatic locks tied into the anti baby kidnapping systems.

 

[FyrBldgGuy]

Man-traps, sally ports, any of these types of control systems still boil down to access controlled egress doors.

1008.1.3.4 Access-controlled egress doors. Apply the conditions required.

 

[LGreene]

Thanks everyone. Since the access-controlled egress doors section requires a sensor to unlock the door upon the approach of a building occupant, it doesn't completely answer the mantrap question. On a mantrap, even if there's a sensor to unlock the first door in the series (as you exit), that door won't open if the second door is already open. A mantrap could be done with delayed egress locks, but usually standard mag-locks are used. The locks used in hospital maternity wards are usually delayed egress locks but there isn't a series of doors that create a mantrap, just a door (in one or more locations) which goes into delayed egress mode when a baby's anklet comes into proximity.

The mantrap that I described in my original post is similar to a sallyport, as defined in section 408 pertaining to I-3 occupancies: "SALLYPORT. A security vestibule with two or more doors or gates where the intended purpose is to prevent continuous and unobstructed passage by allowing the release of only one door or gate at a time." That section allows a sallyport/mantrap in certain conditions: "408.3.7 Sallyports. A sallyport shall be permitted in a means of egress where there are provisions for continuous and unobstructed passage through the sallyport during an emergency egress condition." This only applies to I-3 though.

If banks are installing systems which trap bank robbers (and everyone else), I guess this must be up to the local AHJ?

I'm sorry cda, this makes my head hurt too. :-(

 

[cda]

1. we look at each set up on case by case basis

2. the mantrap set up you describe would not be approved in our ahj, if it was a required exit door

3. sometimes stuff gets installed that the ahj does not know about until it is brought to thier attention

 

[RJJ]

I agree with CDA last response! Case by case. Have approved several. However, us in the north can deal with multiple issue at one time.

 

[FyrBldgGuy]

The term man trap is not supposed to be equal to death trap. Security is not supposed to overrule safety. Even in I occupancies where egress is limited there is a requirement for constant suppervision. An airlock should have some kind of override. If jewerly stores, banks or other locations have security access points they should be under constant supervision and allow egress when the fire alarm is in alarm.

 

[peach]

safety first.. security second. In the case of clean rooms .. safety could mean keeping the bad bugs in the room.

 

[Wayne]

This makes me think of man traps like what we have at the airport to go from non-secure to the sterile (secure) areas or vice versa.

 

[cda]

Wayne's world, Wayne's world, excellant, welcome to the board

just a note, not everyone on the board is as nice as me

 

[FM William Burns]

That's true....you are a charmer