|
|
|
|
|
|
Carbon
Dioxide Systems
Frequently
Asked Questions (FAQs)
|
- When protecting a subfloor
only with CO2, are there any guidelines
to follow for design to help reduce CO2
lost through the subfloor?
- When
protecting a subfloor only with CO2, are
there any guidelines to follow for design
to help reduce CO2 lost through the subfloor?
Subfloor
hazards involving dry electrical wiring
are protected as deep-seated fires requiring
a 50% design concentration of CO2. For
deep-seated fires, the design concentration
shall be achieved within 7 minutes, but
the rate shall be not less than that required
to develop a concentration of 30 percent
in 2 minutes.
Wiring and the minimal height of subfloors
can cause the CO2 to be deflected upon
discharge. This deflection, if in the
direction of the floor tiles, can cause
the CO2 to flow up through any openings
into the room or space above. Because
the total CO2 flow rate required to reach
30% concentration in 2 minutes is constant
for a volume, increasing the number of
nozzles reduces the flow requirement per
nozzle (lbs. Of CO2 per minute), which
reduces the velocity of the CO2 discharge
per nozzle. Therefore, Ansul recommends
reducing nozzle spacing from 20 ft. to
15 ft. between nozzles and using more
nozzles when protecting subfloors.
The type of nozzle utilized also will
make a difference in velocity. A “D”
nozzle will have a softer velocity than
a “Baffle” nozzle. With the
“D” nozzle, the CO2 makes
a directional change out of the nozzle
orifice insert and is forced up against
the deflector in the back of the nozzle.
The CO2 is then forced past the deflector
tabs and out against the sides of the
discharge horn. The turbulence created
inside the nozzle creates a soft cone
shaped discharge pattern.
However, the only way to verify that proper
concentration will be achieved is to run
a discharge test.
|
|
| |
| |
|
|
|
|
