VAC Trip on Generator Running

Manman

2013-07-21 7:47 pm

Dear Fire Service Professional,

Back ground.

-There are 2 non-FSI generators located at 2 adjacent rooms, Genset Rm A and Genset Rm B.

-Each of the genset room is installed with individual Exhaust Fan, with flow rate 20000L/s.

-EAF-A for Genset Rm A, EAF-B for Genset Rm B

-These EAFs will operate when genset running.

-The exhaust louver for EAF-A is directly to outdoor, while there is a section of airduct connected to EAF-B running across the high level of Genset Rm A prior to the exhaust louver, at somewhere of EAF-A's exhaust louver is.

Q1, My question is if there is a fire alarm, should the above EAFs trip?

Q2 If the fire occur in Genset Rm A, should the above EAFs trip?

Q3 If the fire occur in Genset Rm B, should the above EAFs trip?

Thanks in advance.......

回答 (1)

Jenkin

2013-07-24 11:32 pm

✔ 最佳答案

According to:
Code of Practice for Minimum Fire Service Installations and Equipment: Item 5.27(f) individual plant rooms,..., ventilated directly...to outside.
and
FSD Circulation Letter No. 5/2005 Ventilation/Air Conditioning (VAC) Control System Case 8/1, 8/3,

the exhaust/ventilation fans are not required to trip in fire alarm (in all three cases)

In review of the physical installation, given the ventilation duct from Room B through Room A to outside should have the fire damper (strong enough to hold) to close (in case of Q2 fire in Room A or Q3 fire in Room B). Although, the fan is not required to trip, in either case due to the compartmentation requirement with fire damper closed, the EAF in Room B (such large flow rate) will not be able to vent out.

In order to be able to continuous run EAF in Room B for Q2 (fire in Room A), it may be necessary to design to "enclose" the duct from Room B though Room A to outside inside Room A as fire rated compartment isolated from Room A.

So in principle, all Qs are No need to trip. But in reality operation consideration, some careful design of the duct/route and operation controls may be required to determine whether you want to run such a fan in a "firing" room.

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