[dd251] Re: Reply to Brian
- From: Stewart Kidd <stewart-kidd@xxxxxxxxxxxxx>
- To: dd251@xxxxxxxxxxxxx
- Date: Fri, 24 Jan 2003 14:33:18 +0000
I think one of the problems is that there is no generally applicable
'design standard' for mist systems the way there is for CO2,
sprinklers and so on.
The IMO standard mentioned in an earlier thread is a marine standard
(International Maritime Organisation) and as such may be no more than
a useful reference for non-shipboard applications.
There are actually a number of systems out there - one large company
markets both a low pressure and high pressure system. There are
also systems utilising external gas storage, pumps, chemical agents
and even explosive cartridges.
The difficulty is in drawing parallels between kit approved for some
uses but not for others. Don't forget it's important that the system
be design to a standard and the components also be manufactured to a
standard.
I think it is reasonable to draw an analogy with deluge (high and
medium velocity water spray) systems which were introduced in the
absence of any standards - they all did much the same but in
different ways, at different pressures, with different application
rates and using different components. Even now, 40 years later we
still have no BS or EN design standard for these ( there is an NFPA
standard).
Useful thread in a useful forum - keep the thoughts coming
Stewart Kidd
(in his personal capacity as a consultant)
>Members,
> there appears to be two types of water mist pressure systems
>available on the market at the present;
>1) the high pressure type mentioned below
>2) a low pressure mist system that operates at between 1.5 bar to 8 bar
>pressure provided by companies such as "Aquamist Fire Technology" does
>either comply to current standards
> David
>
>-----Original Message-----
>From: William [mailto:william@xxxxxxxxxxxxxxxxxxx]
>Sent: 22 January 2003 17:41
>To: dd251@xxxxxxxxxxxxx
>Subject: [dd251] Reply to Brian
>
>
>Members
>
>Thank you to Brian for his comments on my questions put forward.
>
>I am still looking for answers but will address some of Brian,s comments
>
>1) A water mist system works at higher pressure than a normal sprinkler
>system. Again what pressure is it 200 bar?
>
>2) My point is that there are certain requirements to pipework and fittings
>to be listed within the standards. For example CPVC has a pressure rating
>and would not comply with certain sytems.Are you saying that any pipe can b=
e
>used to link sprinklers? The standards are clear on this issue
>
>3) Residential sprinkler heads are listed and within a standard example NFP=
A
>13D, The NFPA 13D standard can be applied throughout the world even in
>Barbados. As this is a international standard this can also be used with
>possible relaxation to local building codes. I must ask the question again
>is there any mist sprinkler head listed for RESIDENTIAL use.
>
>4) It is a fact that mist systems can be prone to blockages as the aperture
>is very small. In lab conditions the system is perfect but when filled with
>standing water for years this then becomes quite the reverse.
>
>5) Leaking diaphram seals are on the pressure cylinders and not on sprinkle=
r
>heads.Are fire extinguishers checked?
>
>6) Normal sprinkler systems are a different fluid catogory on a water issue
>than a mist or sprinkler system with additives. A single check valve is
>required for cat 2 systems. Any other type of system has to gain water
>approval (United Utilites North west water) if connected to towns main
>
>7) Irrespective of what happens in the USA its what happens here. There are
>systems that are linked to plumbing and used in USA and conform to NFPA 13D
>but are cat 1 in water regs and at the moment they no water approval. so th=
e
>answer is in above at 6
>
>The research you have done is good but you have to know systems and
>standards to make things work throughout the world.
>
>Sprinklers do have a major role in life safety and construction. but they
>must comply with standards and when I am satisfied that a water mist system
>complies to a standard that is for residential use then we can install
>them.This is why I am looking for answers
>Companies who install systems or products not complying to standards for
>which they are deemed for leave themselves and clients open for litigation
>and prosecution for negligence.
>
>
>William
>
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