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vesda question
#1
we have a site with 2 vesda's

1 - 1 pipe covering comms room gnd flr with 1 sample hole in the floor void at pipe end, going through an UNPROTECTED RISER and back into the roof void of the same area with 3 sample holes in the roof void. It definitely needs 1 more sample hole in the floor void due to room size (bigger than 7.5 metre in certain directions), does it need 3 sample holes in the floor void as per the ceiling void sample holes? And should we have sample holes where the pipe runs vertically through an unprotected riser? If so at what hole spacing as the pipe is vertical?

2 - 1 pipe covering comms room 1st flr with 1 sample hole in the floor void at pipe end, going vertically through an UNPROTECTED RISER and back into the roof void of the same area with 3 sample holes in the roof void. It does not need more sample holes in the floor void due to room size, but should it need 3 sample holes as per the ceiling void sample holes? And should we have sample holes where the pipe runs vertically through an unprotected riser? If so at what hole spacing in a vertical pipe? Also the pipe for the 1st floor runs horizontally under a mesh floor in the (unstopped) riser so should any holes in this horizontal section be closer together to catch rising smoke from the ground floor riser underneath?

And I know we should have PIPECAD and a FRA but guess what we don't have any info! No idea on sampling class. No paperwork, units are approx. year 2000. The rest of the building is L1. The vesda's are both covering comms rooms with house system afd in the main area of the comms room and vesda's linked into the main system for fire and fault

ta!
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#2
If the systems are supposed to meet BS 6266 requirements then think of each hole as a detector and use the reduced spacing factors quoted in the BS.

Presumably the VESDA is not being used to control gas suppression?

You may need to be a little careful with air flows/pressures in the voids where the sampling pipe is drawing from all three areas.

Technically the rooms should have primary protection on the return air as any smoke is likely to get sucked in and filtered long before ever being sucked into the pipework ......
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#3
Pipecad wont help you much you need Aspire for VESDA!!


Anyway as ESP said with regards hole spacings, just go careful with the diameter...…. which is why you should use Aspire...… with the small number of holes you have stick with the same as you already have got and you should be ok...….. as long as they are around  3 - 4 mm and not 6-7mm.

One of the most important things with VESDA is the air flow, what VESDA have you got Laser plus? Laser compact?


Check the raw flow before you do anything, should be around 900- 1000 @ 100% (give or take a bit). If its 500 @100% you either haven't got enough holes or the pipe is blocked and its been re-normalised, if its 800 @ 85% stick a hoover on it and it should pop back upto around 100%. (assuming its a VLP or VLC)

Also don't forget if the single pipe is covering ,multiple "areas" you won't know which bit is on fire! eg is the riser on fire or the ceiling void?
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#4
They are vesda compacts. Not controlling gas suppression no.
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#5
(12-02-2020, 08:41 AM)alonso Wrote: They are vesda compacts. Not controlling gas suppression no.

Should be ok those compacts are pretty good. 

If you can give me the following I will try a very rough design for you length of pipe, number of holes, hole spacing and hole diameter. And any capillaries?

Don’t forget the compact is now obsolete so if it is 20
Years old it may be worth considering replacement
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