Extinguishing system in cabinet enclosures.

[Allen Higginson]

Just looking an opinion or two - I am currently looking at a proposed extinguishing system protecting cabinet enclosures.The client has already had a solution provided to then using an inert gas system but our guys have raised concerns about using inert because of the discharge pressures involved and possible damage to the enclosures.Their opinion is to use HFC-227ea  on this occasion (our inert gases are either CO2 or nitrogen).

[John Webb]

Do the cabinets contain electrical equipment, flammable liquids or....?
How is the discharge initiated?

[kurnal]

Before buying any halon replacement system personally I would seek some assurances from the supplier in respect of sustainability should future environmental legislation change.

Other than that reservation, it does offer advantages over the simple inert gases adn particularly over CO2 on computer sytems.

An alternative solution might be to consider oxyreduct by Wagner to cover the room itself rather than the cabinets. Or consider whether,  if staff are on site to act,  early detection may be the answer- such as Vesda sniffing inside the cabinets to detect a fire before it starts?

[Allen Higginson]

Thanks for the replies - the cabinets control burners that are on generators that provide power to most of Northern Ireland! Although the voltages involved are low (<12v as they are only control signals) and there is plenty of ventilation within the cabinets they have been surveyed by the parent company and they want automated extinguishing using dertection within the cabinets.These will be on the double knock principle.
I know where you're coming from Kumal in relaltion to 227 and other hfc gases and their longevity but it is an alternative in view of the pressure problems within the cabinets.
TBH we are providing a comparitive quote and it has to be as "like for like" as possible.

[Galeon]

Ig 55 ?

[Allen Higginson]

Ig 55 ?

That was our initial plan but we don't do containers less than 80 litre and you can't half fill them - actually,I've contradicted myself there by listening to an "expert" in relation to asset damage.The Sinorix CDT is Ig55 stored at 300 bar but limited to 60 bar at the outlet.The problem I have is the cylinder size.

[Galeon]

Pity you cant get to put them outside and pipe it in , apparently it don't freeze either

[Allen Higginson]

Pity you cant get to put them outside and pipe it in , apparently it don't freeze either

The issue is the quantity of gas as we planned to mount/locate the cylinder beside the cabinets.I have been told that you can't half fill a cylinder for the amount that we need (apparantly).

[kurnal]

There are several American companies that do these small self contained systems- I was looking at some a while ago and will check my notes tomorrow to see if I recorded the manufacturers.
The most basic was a small 2kg container of halon equivalent connected to a frangible plastic tube that lead round the machine and if the tube melted the gas was discharged. Certainly not double knock and obviously not very sensitive, may be ok once a fire starts and if one shot from one outlet can be guaranteed to flood all areas- my cabinets were multicompartment so I dismissed this and carried on looking. I did see some similar systems that were smoke detector controlled but by then my client had decided to go for detection and manual intervention instead.

[patrickhamblin]

I would make three points - if there is 'plenty of ventilation' how will the concentration be maintained for a satisfactory time to meet the requirements of the Design Codes (BS ISO 14520); if the discharge is in such a small cabinet, has the aspect of damage to equipment simply from the discharge been considered and what is being done on detection of a fire to isolate the source (i.e. switch off power) to prevent reignition?
I would prefer to see aspirating smoke detection and good emergency response (assuming the location is permanently manned) rather than extinguishing gas detection in this situation. I believe far less damage would be done.

[Goodsparks]

http://www.firetrace.co.uk/products.html

Guys seemed quite helpful when I last dealt with them.

Paul

[Allen Higginson]

I would make three points - if there is 'plenty of ventilation' how will the concentration be maintained for a satisfactory time to meet the requirements of the Design Codes (BS ISO 14520); if the discharge is in such a small cabinet, has the aspect of damage to equipment simply from the discharge been considered and what is being done on detection of a fire to isolate the source (i.e. switch off power) to prevent reignition?
I would prefer to see aspirating smoke detection and good emergency response (assuming the location is permanently manned) rather than extinguishing gas detection in this situation. I believe far less damage would be done.

The cabs are probably as secure as any area protected by an inert gas can be (integrity tests N/A) but using IG55 through our system drops the pressure at the point of discharge (ie - nozzle).
I would agree that a VESDA (or equvalent) detection system would be more advantageous in this application as they could decide locally to deploy a portable extinguisher at whatever unit has indicated a smoke detected source.
Shutting the power off isn't a option.

[The Reiver]

What size are these cabinets ?

I am thinking along the same lines as Goodsparks here. Automatic but direct attack to fire source rather than total cabinet flood.
Therefore the "high pressure upon release" variable is taken out of the equation. There will of course be some release pressure but nothing  more than you would come across with a hand portable

I am presuming by "possible damage to the enclosures" you are refering to sudden atmospheric expansion upon discharge.

[Psuedonym]

There are internal cabinet (server type cabinets, typically 5/6 shelves) enclosure systems out there if its of any interest. Gloria desiged a system many moons ago (it may or may not still be available I haven't checked, sorry): an automatic self contained (Detection and expellant release) Co2 system which was fitted within a cabinet unit designed and manufactured specifically to slide straight into a cabinet. The only "fitting" required was fitting four nuts and screws into the cabinet shelving.
A 2Kg Co2 unit was easily replacable (test/recharge) and any additional internal pressure would be dealt with via the existing cooling fan fitted at the cabinet roof and side vents.
As the co2 was a limited amount (2Kg) the room integrity would not be affected.

[AnthonyB]

Not mentioned as a standard UK stock product on Gloria.co.uk, but Gloria does still make them:

 http://tinyurl.com/5da26t   (shortened from the mile long address on gloria.de)

Sadly you need to speak German as UTC got rid of their old (& better) dual language site