7273-4 quicky

[David Rooney]

Just checking ..... 

If a door is deemed to be Category A regardless of whether it's held open or electronically latched then the requirement is that this door must release under all the EN54-2 fault indication requirements.

Meaning that even a latched door (secured closed for a reason) should open in the event (for example) of the local smoke detector being isolated or going into fault.

I realise the standard makes provision for a variation if the door is to remain latched in the event of such a fault but is this a little overkill??

[colin todd]

Mickey,  In the case of isolation the code only requires Cat A locked doors to release if the locking depends on the detector for its correct operation.  Locked doors do  not depend on operation of detection for their release so whether the detector fails to detect fire or not does not matter.  Held-open doors rely on the detection to close the door, so surely if the detection is not available to do so the doors should close.

[David Rooney]

But I am talking about a detector local to the Cat A door, not a detector on the fifth floor causing a ground floor door to release.

So surely a Cat A locked door on a means of escape corridor is relying on the local detection in that same corridor to release that door ...

So if the local detector is isolated or removed the door won't release as a result of smoke in that corridor .....  the green emergency exit point can't be relied upon as this only allows free travel in one direction therefore if the local detector is isolated the locked door must release n'est-ce pas ??

[colin todd]

You dont need any detection for locked fire exits-you could have had a manual system in the first place.

[David Rooney]

Thanks Colin but let me explain again .....  we have a leisure centre with a large basement area full of corridors / changing rooms, kitchens / offices etc.

Not ideal but that's what we are dealt.

There are some cross corridor doors with access control to prevent the public from wandering into the office areas. However, the alternative means of escape for the public is through the same office areas. Hence we need to release these electronically latched cross corridor doors on a fire condition to allow egress.

The doors in accord with Table B2 are Cat A Critical.

So my question is ..... This is a Cat A door and as such the fail safe requirements (regardless of whether it is held open on a magnet or locked closed via a latch) are the same as for any other Cat A door .... ie isolate the Local detectors (or generate any of the EN54-2 fault requirements) that may effect that door and it should unlock?

[David Rooney]

So .... is a CAT A magnetically retained open door treated the same as a CAT A electronically locked door

To me the answer is yes ..... but it has all sorts of implications for the security of the building unless we ignore it ....... !!

[colin todd]

Mickey, to my mind it is simple and you are making it unnecessarily complicated.

1. If there had been no doors, would you have needed AFD for compliance with legislation.  NO: Go to Q2.  YES: You need to release the doors if any detector that would trigger an evacuation, such that the doors will be used, is disabled.

2. Would you have been allowed to have the maglocks without any AFD.  NO: See response to the YES above.  YES: You only need to release the doors if a MCP is disabled.

Look at this way, Mickey. If there is no need to evacuate the public when the detectors in question operate, but we have AFD anyhow and so that is what will normally happen, there is no need to release the dooors when the detectors arent there.

[David Rooney]

Thank you Colin .... I really do appreciate your patience ....   

ahhhh .... ok... I think I'm understanding..... so ...... in my particular basement corridor Q1 = Yes - I need to release the doors ..... Q2 = has to be NO because we have to have AFD regardless

Whereas in a typical office environment Q1 may well = No and Q2 would therefore = Yes ...... 

Top man .......and God Bless the Queen ....