Dorgard (Again?)

[K Lard]

Would anyone accept Dorgards to a staircase in an office environment (Ground & first floor only) where there is no detection (category M only) and there are three staircases? They were probably installed prior to 2007 when BS 7273-4 came out.

[kurnal]

No I would see smoke detection on both sides of all doors controlled by the Dorgard as a minimum in all cases.

[AnthonyB]

No, far too much chance of fire (or more importantly smoke & combustion products) spreading unnoticed through the open doors. Even the original auto release doors had to have local AFD decades ago, there is no reason not to keep the same principle now.

[wee brian]

ditto - must have detection

[K Lard]

Thanks for that - it’s mirrored my own thoughts. Looks like it’s a minimum of a category M/L5 with detection along the whole of the corridor and one detector in the landing (To satisfy the BS). Don’t know whether they will go for that - if they take the Dorgards off they will end up being wedged open leaving them worse off.

A bit of history – in 2003 CACFOA recommended that a detector either side of the door would not be sufficient (Extract):

‘The practice of using dedicated smoke detectors either side of corridor
doors that are to be held open by a door release mechanism should be
discontinued. This is because studies have found that smoke entering the
corridor from an adjacent room may not have sufficient buoyancy, movement
and directional flow to actuate the dedicated detector heads.’

[colin todd]

Big Al,  Lumpa is right. Detectors either side of the door went out with the 4 pennies in the Bathmat Lock phone box (now sadly destroyed by vandals) to send the stop message to the Derby and Joan control.  Have you been too busy answering everyone's questions to do your CPD Big Al.  Try BS 7273-4 and dont worry about what a bunch of fireman said on behalf of CFOA.  They never did understand the subject of door release.  I liked it when they were called CACFOA as the first three letters reflected their output.

[kurnal]

Big Al,  Lumpa is right. Detectors either side of the door went out with the 4 pennies in the Bathmat Lock phone box (now sadly destroyed by vandals) to send the stop message to the Derby and Joan control.  Have you been too busy answering everyone's questions to do your CPD Big Al.  Try BS 7273-4 and dont worry about what a bunch of fireman said on behalf of CFOA.  They never did understand the subject of door release.  I liked it when they were called CACFOA as the first three letters reflected their output.

Have it your own way Colin but I reiterate that my simple answer to the question posed still stands good -  smoke detection on both sides of all doors controlled by the Dorgard is always required. 

Whether that detection is provided and sited in accordance with the early CACFOA  guidance  that stood us in good stead for so many years  or provided and sited  in accordance with BS7273-4 is immaterial to the fundamental question being posed.

[Davo]

CT

If the smoke rises and sets off the detector, that's good
If the smoke doesn't rise sufficiently, what have you lost by having the detectors??

davo
fogged up

[jokar]

and the fire risk in these premises is?  The probability of a fire is minimal, the probability of it not being detected early is minimal and the chance of the escape route being compromised is minimal as well.  Dorguard are acoustic so they will oprate when a person, decent detector, operates the manual call point. 

[Mike Buckley]

I would agree with jokar, you need to look at the whole building. If the basic brief is a two storey building, ground and first floor, and three staircases. Travel distances, alternative means of escape, interior layout, no sleeping risk? Do they need dorgards at all?

In situations like this I have sometimes suggested hook and eye with the hook fitted upside down, so that it is held in place by friction and if the door is knocked it falls out and the door closes. It stops the door being wedged and in the jostle during a fire evacuation it is easily dislodged and the door will close. OK no good for protected escape routes etc.

[kurnal]

I have no idea where we are going with this it could easily develop into a pythonesqe living in a cardboard box sketch.

I would agree with jokar that the risk assessment should identify whether fire doors are needed here or not and whether persons would be at risk if they were open in the incipient stages of a fire before the alarm was raised. But beyond that if they are a requirement then they should not be fitted with anything that might prevent them from performing their fire protection role.

[David Rooney]

7273 pt 4 says....


13.2.4 Where an electrically powered hold-open device is fitted to a fire door between a corridor and a stairway, a Category L5 system
should conform to the following recommendations (see Figure 4).

a) Smoke detectors should be provided in the section of corridor that forms the route to the stairway.

b) At least one of the smoke detectors recommended in 13.2.4a) should be located between 0.5 m and 1.5 m horizontally of the
door opening (see Note 2).

c) A smoke detector should be located on the ceiling of the adjacent landing within the stairway enclosure.


For all the reasons stated above detectors installed either side of the door is no longer acceptable and basically has been proven to be worthless in many circumstances (otherwise the recommendation would still be in place).

If the end user wants doors held open then his fire detection system needs to be up to scratch, it goes hand in hand and is not an "either or".

So why do fire officers / assessors constantly offer and accept watered down compromises on the basis that "something is better than nothing" when "something" - as in detectors either side of the door in this case is clearly non compliant and in practical terms does nothing for the safety of the end user and is therefore a waste of money??

Tell the end user to meet the minimum standards for AFD or put your name (not his) to a variation based on your risk assessment or do away with the dorguards and risk prosecution if he gets caught with a wedgey.

[colin todd]

Big Al,  I hate to nag you about your CPD, but CFOA changed its advice when you still had a full head of heair and told people that detectors either side of the Door are NOT sufficient.  it was one of the few things that CFOA ever got right (excluding CFOA(S) naturally).  But you are right, that the CORRECTED  advice did stand us in good stead.

[kurnal]

Thanks for that Dave.
Look the point I was trying to make - clearly unsuccessfully- was that on one side of the door there is a corridor and on the other side of the door there is a staircase. Currently there are no smoke detectors anywhere. If a dorgard is  to be used then there needs to be smoke detectors  covering either side of the door.  However I did not set out to offer design guidance for the OP and did not suggest that the detectors should be part of a system installed in accordance with BS7273-4 or  BS5839 Lx or point detectors within xmetres of the door for that matter as per the original or modified CFOA guidance.  

it was just a simple point simply made. I accept that perhaps I did not make the best choice of words. Perhaps I could learn a lot from Wee B who made the same point but more briefly. Perhaps I should have said detection not detectors. Oh well.

Starting to think this forum has had its day. How do you keep fire engineers so positive?  

[nearlythere]

Thanks for that Dave.
Look the point I was trying to make - clearly unsuccessfully- was that on one side of the door there is a corridor and on the other side of the door there is a staircase. Currently there are no smoke detectors anywhere. If a dorgard is  to be used then there needs to be smoke detectors  covering either side of the door.  However I did not set out to offer design guidance for the OP and did not suggest that the detectors should be part of a system installed in accordance with BS7273-4 or  BS5839 Lx or point detectors within xmetres of the door for that matter as per the original or modified CFOA guidance.  

it was just a simple point simply made. I accept that perhaps I did not make the best choice of words. Perhaps I could learn a lot from Wee B who made the same point but more briefly. Perhaps I should have said detection not detectors. Oh well.

Starting to think this forum has had its day. How do you keep fire engineers so positive?  

How was your recent trip K? Hope you behaved?