Carbon Dioxide
System Design
Chapter 9
Page 257
1
Objectives
• Demonstrate understanding of the carbon
dioxide phase diagram
• Explain why storing carbon dioxide in its
liquid form is desirable
• Describe two methods for maintaining
carbon dioxide in its liquid form, using the
carbon dioxide phase diagram as a basis
• List potential uses for a carbon dioxide fire
protection system
2
Objectives
• Detail the limitations and personnel
concerns that must be considered when
specifying or designing a carbon dioxide
system
• Compare and contrast the types of carbon
dioxide systems
• Calculate the carbon dioxide required for a
rate-by-volume or rate-by-area local
application fire protection system
3
Objectives
• Calculate the carbon dioxide required for a
total flooding application fire protection
system
4
Carbon Dioxide
• Carbon dioxide: a gaseous fire protection
agent
– Chemical designation CO2
• Phase diagram: a graph that represents
the physical state of a specific substance
at varying pressures and temperatures
5
Triple Point
6
Carbon Dioxide
• Triple point: point at which carbon dioxide
exists in all three states simultaneously
• Critical temperature: temperature
beyond which carbon dioxide can exist
only in its vapor phase
7
Carbon Dioxide Storage
• High-Pressure Cylinders
• Low-Pressure Storage Containers
• Determination of High Pressure Versus
Low Pressure
8
9
Ex. 9-1: Calculating Carbon
Dioxide Cylinder Quantity
10
Uses For Carbon Dioxide
Systems
• Carbon dioxide is effective extinguishant:
– Ordinary combustibles—Class A commodities
– Flammable liquids—Class B commodities
– Electrical hazards—Class C commodities
11
Carbon Dioxide System
Limitations
• Not to be used for materials containing
their own oxygen supply, for hazards
involving reactive metals such as
magnesium, and for metal hydrides
• Personnel Hazards Related to Carbon
Dioxide
12
Carbon Dioxide System
Limitations
• Actions to protect personnel
– Continuous predischarge alarms
– Breathing apparatus
– Voice alarm systems
– Exits
– Signs
– Training procedures
13
Carbon Dioxide System
Limitations
• Actions to protect personnel
– Time delay
– Manual activation
– Manual override
– Scented gas
14
Types Of Carbon Dioxide
Systems
• Four types of carbon dioxide systems are
recognized by NFPA 12:
– Total flooding carbon dioxide systems
– Local application carbon dioxide systems
– Hand hose line carbon dioxide systems
– Standpipe systems with mobile supply
15
Total Flooding
16
Total Flooding
17
Local Application
18
Local Application Carbon Dioxide
System Design Procedure
• Design methods for local application design
– Rate-by-volume method
– Rate-by-area method
• Each method applies carbon dioxide
directly on an object without the intent of
filling a volume with carbon dioxide
18
Rate-By-Volume Carbon Dioxide
Local Application: Design Procedure
• Rate-by-volume method: a method of
local application of carbon dioxide where
an imaginary volume larger than the
hazard is created to account for the
dissipation and loss of carbon dioxide
during discharge
19
Rate-By-Volume Carbon Dioxide Local
Application: Design Procedure
• Local Application Imaginary Volume
Calculation—Raised 2 Feet Above Solid
Floor
• Local Application Imaginary Volume
Calculation—Raised Less Than 2 Feet
Above Solid Floor
• Determination of Local Application RateBy-Area Carbon Dioxide Quantity—Walls
20
Remote From Hazard
Rate-By-Volume Carbon Dioxide Local
Application: Design Procedure
• Determination of Local Application RateBy-Area Carbon Dioxide Quantity—Walls
Very Close to Hazard
• Determination of Local Application Carbon
Dioxide Weight
21
Local Application Imaginary Volume
Calculation—Mounted to Solid Floor
• The design volume of an object mounted
to a solid floor is the product of the
• length, width, and height of the imaginary
volume, as shown in Figure 9-11.
• V imaginary = (length + 4 ft.) x (width + 4
ft.) x (height + 2 ft.)
• No deduction is permitted for any solid
23
objects within the imaginary volume.
Local Application Imaginary Volume
Calculation—Raised 2 Feet (0.6 m)
Above Solid Floor
• The design volume of an object mounted
to a solid floor is the product of the
• length, width, and height of the imaginary
volume, as shown in Figure 9-11.
• V imaginary = (length + 4 ft.) x (width + 4
ft.) x (height + 2 ft.)
• No deduction is permitted for any solid
24
objects within the imaginary volume.
Local Application Imaginary Volume
Calculation—Raised Less Than 2 Feet
Above Solid Floor
• If a hazard is raised less than 2 ft. (0.6 m)
above a solid floor, the imaginary
• volume is:
• V imaginary = (length + 4 ft.) x (width + 4
ft.) x (height + 2 ft.)
• Distance from floor to bottom of hazard
• No deduction is permitted for any solid
25
objects within the imaginary volume.
Determination of Local Application
Rate-By-Area Carbon Dioxide
Quantity—Walls Remote From Hazard
• To determine the minimum rate of carbon
dioxide required, multiply the imaginary volume
by a factor of 1 lb/min/ft 3
• NFPA 12 requires that high-pressure local
application systems have quantities increased
by 40%.
• Low-pressure Systems: R = (V imaginary) x (1
lb/min/ft.3) x High-pressure Systems:
26
• R = (V imaginary) x (1 lb/min/ft.3) x (1.4)
Rate-By-Volume Carbon Dioxide
Local Application: Design Procedure
27
Calculation of Local Application Rate-
28
Calculation of Local Application
Rate-By-Volume Quantity
• Use the rate-by-volume local application method
to determine the carbon dioxide flow rate (R) for
a small newspaper printing press in a very large
room, mounted to a solid floor, protected by a
high-pressure carbon dioxide system.
• The press is 4 ft. in width (W), 3 ft. in length (L),
and 7 ft. in height (H) and is not located near any
walls. Determine the total amount of carbon
dioxide required (W) if the required duration (D)
29
is 30 sec.
Calculation of Local Application
Rate-By-Volume Quantity
• Solution L is given as 3 ft., W is given as 4 ft., H
is given as 7 ft., and D is given as 1⁄2 minute.
• The imaginary volume (V imaginary) for an
object mounted to a solid floor is computed as
follows:
• V imaginary = (length + 4) x (width + 4) x (height
+ 2)
= (3 + 4) x (4 + 4) x (7 + 2)
30
= (7) x (8) x (9)
= 504 ft.3
Calculation of Local Application
Rate-By-Volume Quantity
• The rate of discharge is computed as
follows for a high-pressure local
application system:
R = (V imaginary) x (1 lb/min/ft.3) x (1.4)
= (504 ft.3) x (1 lb/min/ft.3) x (1.4)
= 504 lb/min x (1.4)
= 705.6 lb/min
31
Calculation of Local Application
Rate-By-Volume Quantity
• The total weight of liquid carbon dioxide
required is computed as follows:
W=RxD
= (705.6 lb/min) x (1/2 min)
= 352.8 pounds of carbon dioxide
required
32
Rate-By-Area Local Application:
Design Procedure
• Rate-by-area method: a method of
applying carbon dioxide to a twodimensional surface area based on the
capability of listed nozzles to discharge a
given amount of carbon dioxide over a
fixed area of coverage
• Diptank: a vat used for dipping, coating,
or stripping an object in a flammable liquid28
34
Rate-By-Area Local Application:
Design Procedure
• Drainboard: an object that collects
flammable liquid residue that drips from
the dipped item onto an inclined surface,
allowing the flammable liquid residue to
drain back to the diptank
• Example 9-3 follows. See Figures 9-13
and 9-14 on Pages 281 and 282
30
Total Flooding Carbon Dioxide
System Design Procedure
• Total flooding systems involve analysis not
only of the expected fire but also of the
integrity of the enclosure
• Evaluate Enclosure Integrity
• Evaluate Personnel Hazards
• Evaluate Fire Scenario of Expected Fire
• Accurately Measure Room Volume
31
Room Volumetric Calculation
37
Total Flooding Carbon Dioxide
System Design Procedure (con’t.)
• Determine Type of Combustible
• Determine Minimum Design Concentration (see
Table 9-2, Page 288)
• Determine Volume Factor
• Volume factor: a value used to determine the
amount of carbon dioxide required to be injected
into a room at the minimum design concentration
of 34%
• Determine Basic Quantity of Carbon Dioxide
33
Ex. 9-5: Determination of Minimum
Design Concentration for Total
Flooding Carbon Dioxide Systems
39
Ex. 9-6: Determine Total Flooding
Carbon Dioxide Volume Factor for a
Surface Fire
40
Total Flooding Carbon Dioxide
System Design Procedure
• Determine the Material Conversion Factor
• Material conversion factor: a
dimensionless number that increases the
basic quantity of carbon dioxide for
hazards where the minimum design
concentration exceeds 34%
• Adjust Basic Quantity for Temperature
• Adjust Basic Quantity for Unclosable
36
Openings
Ex. 9-7: Determining the Basic Quantity
of Total Flooding Carbon Dioxide
Volume Factor for a Surface Fire
42
Ex. 9-8: Determining the Total Flooding
Carbon Dioxide Material Conversion
Factor for a Surface Fire
43
Ex. 9-9: Adjusting Carbon Dioxide Total
Flooding Quantity to Account for
Temperature
44
Total Flooding Carbon Dioxide
System Design Procedure
• Carbon Dioxide Total Flooding Discharge
Duration
• Consider Other Scenarios for Loss of Gas
• Extended Rates of Total Flooding Carbon
Dioxide Application
40
Total Flooding Carbon Dioxide
System Design Procedure
• Extended discharge system: system of
small pipes and nozzles that provides a
rate of discharge after the primary
discharge system ceases operation
• Calculate Pressure Relief Venting Area
• Select Carbon Dioxide Containers
• Determine Number of Nozzles
41
Total Flooding Carbon Dioxide
System Design Procedure
• Select Detection System
• Use Carbon Dioxide System Calculation
Form
42
Summary
• Designers must consider personnel
hazards when specifying a carbon dioxide
system for an enclosure
• Carbon dioxide
– Stored in liquid form
– High-pressure cylinders store it room
temperature
– Low-pressure containers store refrigerated
liquid carbon dioxide at a low-pressure
43
Summary
• Carbon dioxide systems can be designed
for
– Total flooding
– Local application
– Hand hose lines
– Standpipe systems with mobile supply
44