SECTION 2 – DESIGN
UL / ULC Ex4623 Fike Clean Agent System w/ FM-200™ Page 3 of 39
FM 3010715 Manual P/N: 06-215 (Rev G) Revision Date: January. 2010
2.4 DETERMINE AGENT QUANTITY
The following steps are necessary to determine the amount of HFC-227ea needed to protect the hazard(s).
2.4.1 DETERMINE THE HAZARD VOLUME
The first step in designing the HFC-227ea system is to determine the volume of the space(s) being protected.
The volume is calculated by multiplying the length x width x height of the space. Sometimes it is necessary to
divide the protected space into smaller segments due to the configuration of the space. Each smaller segment is
then added together to determine the total volume.
As a general rule, the volume used to calculate the quantity of HFC-227ea required should be based on the
empty (gross) volume. Additional considerations include:
The volume taken by solid, non-permeable, and non-removable objects can be deducted from the
protected volume
Any volume that is open to the space being protected must be added (i.e. non-dampered ductwork,
uncloseable openings, etc.)
NOTE: Any object that can be removed from the protected space CANNOT be deducted from the volume.
2.4.2 CALCULATE AGENT REQUIRED
The next step in designing the HFC-227ea system is to determine the base quantity of agent required to provide
the desired concentration within the hazard(s) being protected. This calculation must be based upon two
important criteria: the lowest expected ambient temperature and the design concentration as discussed in
paragraphs 2.2.1, 2.2.2 and 2.2.3.
To determine the agent quantity needed to produce the design concentration level, the Hazard Volume is
multiplied by the factors as determined in the formula below. (Reference: NFPA 2001, Section 3)
V C
W = -- (------------)
S 100 – C
Where: W = Agent Weight in lbs. (kg)
V = Hazard Volume / ft
3
(m
3
)
C = Design Concentration, % by volume
S = Specific Vapor in ft
3
/lb (m
3
/kg)
S = k1 + k2 (t)
Where: k1 = 1.8850, k2 = 0.0046(t), t = temperature (
o
F)
or k1 = 0.1269, k2 = 0.0005(t), t = temperature (
o
C)
NOTE: The equation to calculate S is an approximation. Tables A-3-5.1(k) and A-3-5.1(l) in NFPA 2001 should
be used when calculating the amount of agent for a specific volume.
NOTE: As an alternative, the tables on the next page have been compiled to make it an easier process for the
system designer. The information provided is derived from the formulas shown above.
(Reference: NFPA 2001, Tables A-3-5.1(k) and (l))
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