Inert gas fire fighting systems technologies were amongst the first halon alternatives to be introduced and twenty years on have stood the test of time. The environmental advantages of inert gases is well documented as are a number of less favorable characteristics when compared to halocarbon agents. These include the larger space requirements for the storage cylinders as well as the need for higher pressure pipework and greater over pressurization venting areas. Until recently the technological development in conventional systems was limited to increases in storage pressure from 150 bar to 200 bar and then to 300 bar, which have had the benefit of a reduction in the storage footprint by 25% as the pressure increased from 150 bar to 200 bar and then by 50% when comparing 300 bar to 150 bar. The benefits of these developments however have not been globally realised as the refill infrastructure varies significantly across the globe, with facilities in some countries still limited to 150 bar and in others 200 bar is the maximum available.
The issues of higher pressure pipework and enclosure pressurization is very much dictated by the very nature of the inert gases themselves. Unlike halocarbon agents which are stored as liquids, the inert agents are stored as high pressure gases that exhibit certain properties upon discharge that demand special attention in specifying and designing pipework systems as well as devices to avoid potentially damaging pressurization effects within the protected enclosure. These effects arise in conventional inert gas systems as the agents are discharged. Firstly the relatively high storage pressures cause the agent flow rate to reach a peak in the first few seconds (typically during the initial three to five seconds) of the discharge. This pattern is not efficient from a distribution system point of view as the pipework is sized to handle the peak flow rate before it rapidly reduces, meaning that the piping is actually much larger than needed to handle the average flow rate. The peak flow rate also has to be used to determine the free vent area in the boundary of the protected enclosure, which is needed to allow for the displacement of a relatively large volume of air to avoid over pressurization potentially causing structural damage.
Patented technologies from Tyco Fire Protection Products, including the i-Flow valve technology, horizontal check valve system and the matrix racking system assist in solving some of the drawbacks associated with conventional systems. Firstly the i-Flow valve regulates the pressure, resulting in an even discharge at a constant flow rate for the duration of the effective discharge period. The discharge pattern in this case is much more efficient as it evens out the flow rate without experiencing the peak flow as described earlier. This constant (reduced) flow may permit the system design engineer to reduce the size of the pipework since it is no longer necessary for it handle the initial peak flow associated with conventional systems.
Secondly the system does not need an orifice plate in the pipework to reduce the pressure from the relatively high storage pressure – to the pressure required in the system to ensure effective discharge and distribution of agent, since the pressure reduction has already taken place in the i-Flow valve. An added feature of the i-Flow valve, is that when used in systems featuring selector (or distribution) valves, in the event of a selector valve failing to open, the flow ceases and unlike some constant flow systems the pressure remains at the output pressure of the i-Flow valve and does not reach the cylinder storage pressure. This permits the cylinder and selector valve manifolds to be designed at the same pressure rating as the upstream pipework and not at pressures needed to handle the cylinder storage pressure, - which could be as high as 300 bar, even when closed sections are present in the system. This is an important safety feature consciously designed into the i-Flow valve technology.
The next benefit is that the reduced agent flow rate lowers the over pressurization effects, thereby significantly reducing the venting requirements in the boundary of the protected enclosure, saving both cost and disruption associated with the fitting of over pressurization devices. The i-Flow technology is available for use with both 80 litre and 140 litre cylinders, with the 140 litre cylinder particularly useful where space constraints are a factor.
The development of the i-Flow system horizontal check valve resulted in another patented component. The horizontal check valve may be installed in any orientation, unlike many conventional check valves that need to be installed vertically to be fully effective. This component allows the interconnection of upto 8 cylinders, feeding into a single pipe, thus avoiding manifolds, reducing space and installation costs.
The matrix racking system was designed to allow the system cylinders to be easily installed in challenging locations, for example where the bank needs to wrap around a column or other structure. It also allows for easier maintenance as the racking system requires minimal dismantling when gaining access to a single cylinder, no matter how deeply is it hidden in the bank.
The i-Flow system technology is available to be used with all Inert gas combinations including INERGEN, i3 (using IG-55), IG-01 (Argon) and IG-100 (Nitrogen).
All components in the i-Flow system meet the exacting requirements of the EN12094 harmonized series of standards and carry VdS and CNPP approvals.