Hi All,

As far as I can gather BS7273-4 stipulates certain maximum times for failing safe with door closers which are different for Category A, B or C. Can someone with access to the spec please tell me if there is an maximum activation time from normal fire alarm specified? The maximum time to activation for faults such as short or open circuits is 2 minutes and 6 minutes for loss in radio comms for Cat A and 120 minutes for Cats B & C. There are other documents I've seen that state that the system should behave in fault conditions exactly as it would in fire alarm conditions, so does that imply a maximum of 2 minutes from fire alarm activation?

Also if BS7273-4 are guidlines, and a piece of equipment fails certain time criteria (but otherwise still fails safe in conformance), can that equipment be given a Category A certification if those conditions are noted on the conformance certificate?

Thanks for your help!

Mark.

BS7273-4 controls the activation of hold open devices which means if the fire alarm operates the door will release immediately and if a fault develops on the system the door will fail to safe in a specified time. BS7273-4 provides for fail safe operation of the devices under a wide range of fault conditions and within time constraints, for category A there are 13 fault conditions each one with its own specific time. For Category B and C there are 3 fault conditions as indicated in the category A with some modifications. There is no maximum activation time each condition has its own specific time.

You can use variations from the recommendations with the approval of all interested parties and they must be recorded in the commissioning certificate or the specification for the system.

The author considers it a simple document other’s believe it is very difficult, and I believe to understand it you need to study it which means you should check with the local reference library to see if they can provide a copy or if necessary purchase a copy.

OK, thanks. BTW it is impossible to release the doors 'immediately' if the fire alarm operates assuming no fault conditions, so my question is how long does the spec allow (since it can't be zero)? Is operation under normal conditions (i.e. no fault) actually covered in the BS7273-4 spec, or is that just all about failing safe? My local library doesn't have BS specs so I'd like to know it has the information I need before purchasing one.

Thanks, Mark.

There is a comment in BS 7273 but you may need BS EN 1155:1997 Building hardware. Electrically powered hold-open devices for swing doors. Requirements and test methods, which says, "Upon the removal of of the electric supply and when the applied voltage is reduced to 10% of the rated supply voltage the device shall release and allow the door to close under the control of the door closing device. The hold open device shall release within 3 s of the supply being disconnected." I hope this is what you are looking for but do understand I am no expert on fire alarms and treat this information with caution.