BIG final exit door rams (with simple override) required

[Messy]

I am looking to procure some heavy duty door opening rams for some very large final exits doors which weigh around 300/400kg each.

The double doorsets open inwards and a significant number of persons (several hundred) expected to use the escape route during an evacuation. The rams will be interfaced with the AFD, so in normal operation, the final exit door will be in the open position quickly and in most cases, before the first evacuee gets there.

So far so good........

But the biggest problem is that the rams must be fitted with a simple to operate manual override which will allow the door to be open manually in the event of a failure of the interface. The override must work in be one operation without the use of any key, and be possible to open the door quickly by one person who has never seen the override before.

Has anyone any ideas of where I can find such a device? I don't think this is a unique problem, indeed, there's no issue getting the rams, its the simple override which is proving problematic to find

[kurnal]

Are the users members of the public or employees? If members of the public you might be better to find an alternate fail safe such as PIR on approach or pressure mats. Clearly it will need to be a secure engineered solution as power will be needed to open the doors.
Are the leaves wide enough to incoprorate a different approach eg  seperate interface to each leaf each on a seperate loop?

[Messy]

Thankfully, the exit(s) are for staff only and no public

There is a resilient power supply with a generator back up. The building's power originates from two separate utility company sub stations and has an auto start generator back up. I hadn't thought of using different powers supplies (in this case, different sub stations) to feed each leaf in the pair as I have been concentrating on an override or some kind of local battery UPS.

All solutions will be expensive, but there is no choice as I believe the status quo in untenable and non compliant

Thank you very much for the idea

[kurnal]

I was more thinking in terms of increasing the resilience of the connection to the fire alarm rather than the power supplies. I was thinking that if each leaf was wide enough to be considered in its own right  (say 750mm) then to provide a seperate interface to each door leaf each fed off a seperate fire alarm loop would improve resilience.

The risk of inward opening doors may also be evaluated taking into account the rate at which persons will arrive at the doors, 400 persons sounds scary but will they all arrive at the same time  like a flood or as a trickle?

[lyledunn]

 So the rams require power to open the door. That's a bad start. One assumes that there is some mechanical means to open the doors at the moment but since they open inwards you are assessing this to be inadequate for the circumstances. DNOs are becoming increasingly reluctant to confirm that two separate feeders can be deemed as alternative supplies. Generator back-up is helpful but depends on hook up and classification with respect to change-over time. A serious fire in the main panel could see you without any power at all. Could the doors not be fitted with hydraulic rams where the Pistons are released on failure of a supply?

[kurnal]

Or large gas struts similar to those used to open some single flap smoke vents?

[wee brian]

Most of these things are best arranged to spring open with the alarm system holding them in the closed position (with a magnet etc).

Any power failure releases the door. you can then use a simple panic bar or breakglass to interupt the power supply.

I expect you can get a floor spring that will cope with a 300kg door.

[Messy]

Thanks to all for your input

The latest guess (and it is a guess) is that each door leaf weighs between 150 and 200kg - so 400kg a door set, so not quite as lumpy as I had thought

The door cannot fail to open due to security concerns (there is valuable property within).

I am now trying to collate information from many years of defects and failures to identify the causes of any critical failure - (ie those where both doors failed to open). Kurnal, I believe you are right that the fire alarm link and local door control panel faults are most likely worst offenders so need to be considered as the main areas to be dressed.

The doors are very old and along with the building, they are listed which causes more issues both externally and internally in relation to appearance. I am not sure big springs (even if flush mounted in the floor) would be acceptable. Of course the doors cannot be turned to open out.

We are going to appoint engineers to point us in the right direction on this one, as I am a little stumped. I am aware of a handful of similar doors elsewhere and will be knocking on them soon to enquire what MOE method they use

[Owain]

would it be possible to leave the outer doors opened inwards during staffed hours, and have an inner door / gate / barrier (which satisfies outward-opening fail-safe requirements) to prevent unauthorised access? If the area is not usually occupied PIR sensors would detect unauthorised entry

[Fishy]

For power supplies (if required to be resilient) I'd simply refer to BS 8519.  Tells the sparkies how to design the permutations & combinations of supply arrangements, secondary supplies & change-overs etc.

[Messy]

Owain - Unfortunately, holding the outer doors open is most definitely not an option

Fishy - I was not aware (or did I consider) that BS8519 would be applicable in this case. Very useful info - thanks

As a result of your post I found this short PPT on the subject http://www.voltimum.co.uk/articles/draka-bs-85192010-code-practice-explained

[jayjay]

 Iam still trying to understand in what situation you can have an inward openig exit door for several hundred people and relying on automatic detection to have it open on evacuation. What fail safe/open system would be suitable?

[Messy]

Iam still trying to understand in what situation you can have an inward openig exit door for several hundred people and relying on automatic detection to have it open on evacuation. What fail safe/open system would be suitable?

Its a matter of improving the reliability of the devices by making the resilience of the power supply more robust and providing an easy to use door override in the event of a failure