Meaning of para 5.18 of the ADB

[kurnal]

Please can anybody explain  what 5.18.a.ii on page 55 of the ADB means when it says "Automatic doors..... are provided with a monitored failsafe system for opening the doors if the mains power supply fails"

Exactly what sort of "monitored failsafe system" are we talking about here? Something as simple as a rubber bungee  built into the door as that opens the doors if the power supply fails? Anyone know what was intended when it was written?

[wee brian]

Monitored fail safe is about knowing if your bungee (etc.) is still there or not.

I'e. the bungee should be used to open the door in normal operation. If it fails you will know about it and get a new bunggee (etc.).

If the door powers open and powers closed then the bungee (etc.) will eventually wear out and nobody will know about it.

Of course if you opt for break open doors then the problem goes away.

I think this is all in the standards for sliding doors (or it used to be).....

[kurnal]

Thanks Wee B - I bought the BS for the doors and found that the wording and terminology bears no resemblance to the words used in the ADB- hence the question.

Since posting I came to a slightly different conclusion that may be wide of the mark, I assumed that monitored means that the doors will monitor the power supply and if the power supply should fail the mechanism trips and the bungee will pull the door open without any other action by the user. So the power supply is therefore monitored by the door.

[Midland Retty]

I see what you are saying Kurnal

It would seem a tad over elaborate and a lot of fuss to do that however.

Unless of course it is imperative that staff are aware of any doors which have opened  - such as a care home with dementia patients for example - or have I misunderstood your point Prof?

[kurnal]

No was not thinking in those terms Retty more like a relay within the doors that when de-energised would release the bungee allowing it to open the doors. So the supply is monitored and if it dissapears the door opens.

[Midland Retty]

Ah, I think Im getting confuddled, would you not in those circumstances just have a "failsafe-to-open" mechanism anyway? i.e; if door is powered shut.

[kurnal]

Yes I hope so. I was just querying what 5.18.a.ii on page 55 of the ADB actually means in practical terms when it says "Automatic doors..... are provided with a monitored failsafe system for opening the doors if the mains power supply fails"

What exactly did they mean by "monitored"?

[Midland Retty]

Quite... which is why I wonder if meant that in safety critical areas if the door does failsafe open someone should be alerted.

I cant see any other situation where that would apply.

[nearlythere]

Yes I hope so. I was just querying what 5.18.a.ii on page 55 of the ADB actually means in practical terms when it says "Automatic doors..... are provided with a monitored failsafe system for opening the doors if the mains power supply fails"

What exactly did they mean by "monitored"?

Perhaps an indicator that the means for opening the door in the event of a power failure is functioning. eg that in a safety light.

[wee brian]

As I said.

Monitored fail safe means that the fail safe is monitored. I.e. it should be apparent when it aint working properly.

I'm not making this up.

[kurnal]

Thanks again Wee B. Have you ever seen such an arrangement?

[CivvyFSO]

Monitored fail safe means that the fail safe is monitored. I.e. it should be apparent when it aint working properly.

Kind of a fail safe backup for the fail safe, so to speak?

[nearlythere]

If the failsafe fails, was the failsafe really failsafe safe?

[Phoenix]

If you had a system for opening your doors in the event of power failure then how could you tell if it was working ok if there were no power failures?

Difficult, without simulating the very power failure it's designed for.    

If there is some mechanism for giving a visual or audible warning when the failsafe fails then the manufacturers have kept it a pretty good secret.  

On the whole, I don't think that it's a bad idea to check the doors periodically to ensure that they open on failure of the supply.  I would judge that this is all that is required to "monitor" the failsafe facility.  Once a week wouldn't be onerous.  Also record it in the log book.  

It wouldn't take an electrical genius to fix up a fish tail key to do the job.  

Stu

[kurnal]

Strugglin with the first word OM. but agree with the sentiment.
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