I'll-' is the agent volume requirement (in cubic metres per cubic metre); i.e. the quantity Q (in cubic metres) of agent required at a reference temperature of 20 °С and a pressure of 1,013 bar per cubic metre of protected volume to produce the indicated concentration at the temperature specified:
2r =m'SR
where
Sr is the specific reference volume (in cubic metres per kilogram); i.e. the specific vapour volume at the filling reference temperature for superheated IG-541 vapour at a pressure of 1,013 bar which may be approximated by the formula: SR=k^+k2- TR
where k- = 0,65799; k2 = 0,002239; 7r is the reference temperature (in degrees Celsius), i.e. filling temperature (20 °С in the table).
V is the net volume of hazard (in cubic metres); i.e. the enclosed volume minus the fixed structures impervious to extinguishant.
T is the temperature (in degrees Celsius); i.e. the design temperature in the hazard area.
S is the specific volume (in cubic metres per kilogram); the specific volume of superheated IG-541 vapour at a pressure of 1,013 bar
may be approximated by
S=k^+k2T.
c is the concentration (in percent); i.e. the volumetric concentration of IG-541 in air at the temperature indicated, and a pressure of
1,013 bar absolute.
Table 4 — IG-541 reference extinguishing and design concentrations
|
Fuel |
Extinguishment % by volume |
Minimum design % by volume |
|
Class В Heptane (cup burner) Heptane (room test) |
31,7 37,0 |
48,1 |
|
Surface Class A Wood crib PM MA PP ABS |
28,2 30,7 30,6 30,7 |
39,9 |
|
Higher Hazard Class A |
a |
45,7 |
|
The extinguishment values for the Class В and the Surface Class A fuels are determined by testing in accordance with EN 15004-1:2008, Annexes В and C. The minimum design concentration for the Class В fuel is the higher value of the heptane cup burner or room test heptane extinguishment concentration multiplied by 1,3. The minimum design concentration for Surface Class A fuel is the highest value of the wood crib, PMMA, PP or ABS extinguishment concentrations multiplied by 1,3. In the absence of any of the 4 extinguishment values, the minimum design concentration for Surface Class A shall be that of Higher Hazard Class A. See EN 15004-1:2008, 7.5.1.3, for guidance on Class A fuels. The extinguishing and design concentrations for room-scale test fires are for informational purposes only. Lower and higher extinguishing concentrations than those shown for room-scale test fires may be achieved and allowed when validated by test reports from internationally recognized laboratories. |
||
|
a The minimum design concentration for Higher Hazard Class A fuels shall be the higher of the surface Class A or 95 % of the Class В minimum design concentration. |
||
Safety of personnel
Any hazard to personnel created by the discharge of IG-541 shall be considered in the design of the system.
Potential hazards can arise from the following:
the extinguishant itself, by oxygen reduction;
the combustion products of the fire.
For minimum safety requirements, see EN 15004-1:2008, Clause 5.
Physiological information for IG-541 is given in Table 5.
Table 5 — Physiological information for IG-541
|
Property |
Value % by volume |
|
No observed adverse effect level (NOAEL) |
43 |
|
Lowest observed adverse effect level (LOAEL) |
52 |
|
These values are based on physiological effects in human subjects of hypoxic atmospheres. These values are the functional equivalents of NOAEL and LOAEL values, and correspond to 12 % minimum oxygen for the no-effect level and 10 % minimum oxygen for the low-effect level. |
|
System design
Fill pressure
The fill pressure of the container shall not exceed the values given in Tables 6, 7 and 8 for systems operating at 150 bar at 15 °С, 200 bar at 15 °С and 300 bar 15 °С, respectively.
Other pressures may be used and the minimum design pressure specified accordingly.
The relationships between pressure and temperature are shown in Figures 1,2 and 3.Table 6 — Storage container characteristics for IG-541 —150 bar
|
Property |
Unit |
Value |
|
Filling pressure at 15 °С |
bara |
150 |
|
Maximum container working pressure at 50 °С |
bara |
175 |
|
Reference should be made to Figure 1 for further data on pressure/temperature relationships. |
||
|
a 1 bar = 0,1 MPa = 105 Pa; 1 MPa = 1 N/mm2. |
||
Table 7 — Storage container characteristics for IG-541 — 200 bar
|
Property |
Unit |
Value |
|
Filling pressure at 15 °С |
bara |
200 |
|
Maximum container working pressure at 50 °С |
bara |
235 |
|
Reference should be made to Figure 2 for further data on pressure/temperature relationships. |
||
|
a 1 bar = 0,1 MPa = 105 Pa; 1 MPa = 1 N/mm2. |
||
Table 8 — Storage container characteristics for IG-541 — 300 bar
|
Property |
Unit |
Value |
|
Filling pressure at 15 °С |
bara |
300 |
|
Maximum container working pressure at 50 °С |
bara |
360 |
|
Reference should be made to Figure 3 for further data on pressure/temperature relationships. |
||
|
a 1 bar = 0,1 MPa = 105 Pa; 1 MPa = 1 N/mm2. |
||
Key
X temperature, °С
Y pressure, bar
Figure 1 — Temperature/pressure graph for IG-541 pressurized to 150 bar at 15 °С
X
Key
X temperature, °С
Y pressure, bar
Figure 2 — Temperature/pressure graph for IG-541 pressurized to 200 bar at 15 °С
Key
X temperature, °С
Y pressure, bar
Figure 3 — Temperature/pressure graph for IG-541 pressurized to 300 bar at 15 °С
Superpressurization
Containers for IG-541 are not superpressurized.
Extinguishant quantity
The quantity of extinguishant shall be the minimum required to achieve the design concentration within the hazard volume at the minimum expected temperature, determined using Table 3 and the method according to EN 15004-1:2008, 7.6.
The design concentrations shall be those specified for relevant hazards in Table 4, including a 1,3 safety factor on the extinguishing concentration.
Consideration should be given to increasing this for particular hazards, while seeking advice from the relevant authority.
