A brief outline of the requirements that affect the specification of items which relate to architectural ironmongery and allied products, are as follows:
Locks and latches BS8300
ll lock cases should have either of the following :-
- 72mm centres
- The cylinder should be fitted above the lever handle
- On bathroom and privacy functions, the release turn should be large enough to be able to operate easily
All lock cases should have a backset of no less than 54mm
Latches should perform better than the lowest resistance class of BS EN 12209 (15N).
High performance latches are available which contribute less than 5N resistance to closing.
A minimum diameter of 19mm is required, but does not have to be round in section. The handle should be operable without having to fully grip the handle, have a minimum of 95mm inside dimension between the shank and the return and a minimum of 45mm clearance behind the grip to the door face, excluding roses or plates. Return to door lever handles are not necessary but recommended.
The handle should have a minimum clearance of 45mm from behind the grip to the face of the door or the backing plate. The diameter of the handle should be between 19 and 35mm and at least 400mm in length. To aid the users of wheelchairs pull handles should be fitted horizontally on the doors, which do not have self closing devices. A pull handle should be fitted with a cover rose or trim to provide people with impaired vision easier recognition and provide greater support.
External handles on accessible routes should not be cold to touch. A textured grip would be of assistance together with nylon, nylon coated and other materials, such as wood will all be acceptable. Handles should not have any sharp edges or sudden changes in direction.
Hinges should perform better than the lowest friction requirement of 4N under BS EN 1935. High performance hinges will contribute less than 1N friction per hinge. Hinges with very low friction are efficient in use for reducing the resistance for door closers, which will help keep the power required to a minimum, allowing easier opening of the door leaf.
Door closers and operating forces
The amendments to BS 8300 together with the Technical Memorandum to AD 'M' quote a maximum figure of 30N opening force when measured at 0° (closed) and 22.5N when measured between 30° and 60° (open).
It is also stated that backcheck closers should not operate before 80° (open) and the maximum closing force should not occur between 0° and 15° of the final closing.
It is noted that it can be difficult to measure the opening force at the door edge and that it may be measured in line with the handle, up to 65mm from the edge of the door. The figures may be increased by up to 2N in this situation. Plunger type force gauges should be used but unless of the sophisticated digital variety, they only have an accuracy to within 2 or 3N.
It will be possible to use closers to power size 3 (BS EN 1154) as the minimum requirement on fire doors, providing it has 65% efficiency or better for accessible routes.
The best possible requirement would be door closers having full adjustable power between 2-4 (not selectable) and an efficiency rating of 65% +.
It is therefore important at the design stage to choose the appropriate products for the best performance
- Low friction hinges
- Low bolt resistance on locks if fitted
- Suitable closing device
Also taking into consideration any differentials in air pressure and natural air flow.
The door set will also be affected if it is to be fire / smoke control as the seals will offer resistance to the efficiency of the closing device.
Automatic fire detection and alarm systems
If a Building has an automatic fire detection and alarm system (BS 5839) these doors may be provided with one of the following products which need to conform to BS EN 1155:-
- A closing device incorporating an electro-magnetic/ mechanical hold open/release function. A hold open door closer is not acceptable.
- A closing device used in conjunction with a separate electro-magnet hold open/release unit. It should be born in mind that if this option is used that the magnet is in the same horizontal plane as the closing device i.e. if used with an overhead door closer this should be roughly door height and floor springs near the floor.
- An electro-magnetic 'swing-free' door control device.
Please note that options a) and b) are more suited to corridor applications, whereas c) would be suited to room or office environments.
If, however, an automatic fire alarm system should not be installed a fully automatic door system or low energy power assisted operators would be preferable.
Non-automated fire detection and alarm systems
If this type of system is used it is essential that door closing devices to BS 1154 are adopted, and that after installation the doors are fully tested to ensure that all the necessary recommendations are complied with and any adjustments are made before completion.
At this time all doors must be checked to ensure that closing fully into the frame takes place from any angle and that doors are able to close from as little as 5° opening.
In all cases it is essential that regular inspections are made to ensure that these critical life safety systems are maintained and clearly defined. All the components can effect the efficiency and performance of the doors.
It is stated that a handrail should be :-
- oval or circular profile and have a diameter of at least 40mm but not greater than 50mm.
- Finished so as to provide a visual contrast with the surroundings.
- Easy and comfortable to grip with no sharp edges, smooth and NOT cold to touch and there should be a clearance of between 50 and 60mm between the handrail and the adjacent wall surface.
(Produced or shown by kind permission of Häfele UK, information given correct at time of print Aug 2008)