HI Marcus,

I have just opened up my P.c and caught sight of this debate, which
is an area in which I have been previously involved in some research.

The problems arises in doors which are fire-doors and are unlatched
and rely purely on the closer spring/hydraulics to keep a fire-door
securely closed upon it's seals.

Latched doors in public buildings with lots of traffic are not really
suitable.

Smoke-sealing and fire-doors have to comply with BS.476 Pt 31.1 (and
I believe building regulations Part B, Appendix B.1 for new doors in
alterations, fire-precaution work etc).

Particularly if you were talking about circulation doors across
corridors
or protecting a stair shaft, means of escape. Where smoke leakage under
a pressure of 25 pascals should not exceed 3 cubic metres volume per
metre
of door-seal per hour.

Ever tried putting new smoke seals onto an existing and presumed to be
sound
fire-door in a public building (already subject to draughts and
differential pressures in a stair-shaft) to improve fire-safety? I'm
sure we may have done that thinking we have done a good job.

But how many having specified the work to B.S etc have then gone on to
test
the door over a few hours with a pressure test rig and instrumented the
test
and recorded leakage and sustainability of air-pressures?...at 25
pascals and beyond?

You would be amazed how leaky some 'sound' looking doors, fully sealed,
can be. Obviously the quality of the components and installation is very
influential. We all quote B.S's etc in our specifications, thinking we
have got it covered, then depend upon the ability of the average
commercial contractor, who after all is only trying to make good to some
doors (joinery work)to somehow make it work.

Next time you go shopping to an old established, multi-story type store
with a back of store fire-escape stair and with landings marked up as
refuges. As you walk down the stair and past the doors accessing the
store's various floor levels, if they are shut, as an experiment just
check the chinks of light showing through the door gaps/seals from the
more brightly lit shop interior. Remember B.S permits a bit of leakage
around the lock and hinges.
But it doesn't take much of a gap at 25 pascals to leak quite a lot!.

At 25 pascals and above you would be amazed even with a fairly strong
fire door spring, how some doors can be blown open completely loosing
their
seal. What if this was a refuge door?

Clearly aiming to meet the standards for the protection of all the
buildings
occupants for fire escape and then still making them accessible for
disabled people (25 to 30N max) is quite a task on unlatched doors.

Strangely BS 8300:2001 section 7.3.2 'Fire Doors Fitted with
Self-Closing
Doors',  discusses this very issue, but then in Note 1 talks about a
maximum
closing force of 30N, when what we need for access/egress is a suitable
closer for fire with a suitable opening force. Or am I being too
pedantic here?

O.k, so like hospitals, you can have circulation doors on mag-holdbacks
released upon activation of the alarm system. But isn't this just the
time
when you want to get people (including disabled people) out of the
building
quickly? And disabled people will have to pass through doors then
closed?

A compromise (because I am not sure that there is a perfect and
affordable answer) might be to choose a closer that has the special
properties of having high-strength when shut, to try and maintain the
integrity of BS.476 31.1 etc but which upon opening reduces it's force
needed to push open once moved off it's seals. I will leave you to check
out your own products.

As for closing, latching speed, I suspect that some door-closer models
on the market have better latching/closing speed adjustment than others.
The
ones suitable for electronic security latching where you need to avoid
bounce, so have the characteristics of a decelerating but firm close
could be suitable. But check out, if on a fire-route door, they meet all
the other requirements! Setting the operating pressures at zero to
reduce stiffness may not be the total answer. Maybe this is why
BS.8300:2001 advises caution on the subject. If in a tall building,
subject to stack-effect and variable
pressure conditions you may find that keeping doors regularly adjusted
and
optimized quite an ongoing exercise.

Regards,
Glynn


-----Original Message-----
From: Accessibuilt list [mailto:[log in to unmask]] On Behalf
Of Marcus Ormerod
Sent: 26 June 2003 08:16
To: [log in to unmask]
Subject: door closers

Hi all

Yesterday I was asked about the effect of trying to reduce the closing
force of doors with oil-filled door closers, rather than the spring
mechanism type. This came about since I had generally recommend reducing
the tension on door closers to make doors lighter to open. The
maintenance person said that the only adjustment on an oil filled door
closer is to reduce, or enlarge the size of the aperture through which
the oil passes. However, the net effect of enlarging the hole whilst
making the door easier to open (less oil resistance through the
aperture) was that it would shut quickly as well (the oil flows back
quicker). No other adjustment being available.

If this is the case then recommending adjusting the door closer is going
create a problem as much as it solves one. Has anyone else come across
this issue?

Thanks
marcus

Marcus Ormerod
SURFACE
The University of Salford
Bridgewater Building
Salford
M7 1NU
Tel +44 (0)161 295 5405
Fax +44 (0)161 295 5011
Textphone +44 (0)161 295 3194
Mobile 07887 556425

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