Fixed firefighting systems. Gas extinguishing systems. Physical properties and system design of gas extinguishing systems for IG-541 extinguishant

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'S_R

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: S_R=k^+k₂- T_R

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

5. 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:

1. the extinguishant itself, by oxygen reduction;

2. 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

5. System design

   1. 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

Table 7 — Storage container characteristics for IG-541 — 200 bar

Table 8 — Storage container characteristics for IG-541 — 300 bar

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

Containers for IG-541 are not superpressurized.

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.