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FIRE SAFETY => Fire Alarm Systems => Topic started by: DavyFire on June 27, 2018, 09:57:43 PM

Title: Aspirating smoke detection
Post by: DavyFire on June 27, 2018, 09:57:43 PM
Hi all,
       I have been tasked by a multi-national company to review the fire safety in an 11Kv sub-station on their premises. This is a three storey manufacturing facility built, probably in 70s or 80s. An audit within the company identified the sub-station, which is on the ground floor, as and I quote
The 11Kv substation is critical for all operations at this facility. It has no fixed fire protection, but does have a smoke detection system. However, due to the critical nature of this room and its equipment, we recommend the installation of an air sampling smoke detection system, as air sampling systems react much faster than conventional smoke detection systems. there is no longer a site fire brigade here and the public fire brigade response is around 8 minutes.
The plant have a very rigorous maintenance and testing programme of all the switchgear, contactors etc with corresponding records. No incidents of failures of this equipment. Fire protection measures are tested serviced and maintained regularly.
My query is how much faster would an air sampling unit be compared to conventional unit and could the cost be justified.

Thanks, Dave
Title: Re: Aspirating smoke detection
Post by: Fishy on June 28, 2018, 07:07:55 AM
A BS EN 54-20 compliant ASD may be configured to be much more sensitive than conventional point detectors, depending on the system type chosen.  However, early detection in itself does nothing to decrease fire risk - it's only useful if it causes automatic or manual fire-fighting to be initiated earlier than would otherwise be the case.  To do this, it would (at the very least) need to be incorporated in a Category P (to BS 5839-1) fire alarm system.  You also have to remember that whatever fire protection you throw at it, the probability that the facility will be lost to fire will never drop to zero.

Re: the "...could the cost be justified... question - I suggest that you'd need to undertake a risk analysis to determine that.  I've used the techniques in BS 6266 numerous times to address this type of question and if the risk review is rigorously done (and the right stakeholders are involved) then the answer normally drops out of the process.  BS 6266 is specific to 'electronic data processing installations', but much of it is useable for other types of potentially 'critical' assets. 

There are, in any case, other things that can be done to reduce fire risk in this type of situation - particularly around management (again, BS 6266 has some very relevant recommendations).  CIBSE Guide E also has some useful advice on risk assessment.
Title: Re: Aspirating smoke detection
Post by: DavyFire on June 28, 2018, 10:59:45 PM
       Thanks for the reply.
I have looked at their testing, maintenance and servicing regime of the installed fire protection measures, their staff training and the maintenance and testing of the electrical switchgear. Most is to a good standard, with some shortcomings which will be addressed.
I had posted the query as i had little experience of aspirating smoke detectors and the insurers had requested it.
I would agree with your comments, it is down to safe systems, maintenance, testing, etc to reduce the risk of fire in the first place.
The senior electrican on the plant stated that a failure in this substation would probably be serious anyway and the quicker detection would not be of any benefit. We will pursue the prevention route rather than faster detection.
Title: Re: Aspirating smoke detection
Post by: AnthonyB on June 29, 2018, 07:43:31 PM
Most use of ASD in HV substations we come across is not for super early detection, just detection that can be serviced without entering the room in place of an existing CO2 system. It's cheaper and easier to maintain a new ASD system than a new CO2 system!

Where property protection is essential (& this seems to be rare for HV) then replacement CO2 or aerosol automatic systems have been fitted.
Title: Re: Aspirating smoke detection
Post by: David Rooney on July 02, 2018, 12:11:23 PM
If there's no one on site to react quickly enough I think the aspirating system would be pointless.

If they really want to prevent fire then they consider something like this ...
Title: Re: Aspirating smoke detection
Post by: bevfs on July 30, 2018, 03:45:18 PM
and ensure the insurance provider is happy (in writing)with the system of alarm you intend to use :)