IG01

We saw the need for a highly reliable and effective clean agent system that would have no long-term environmental problems whatsoever. In addition to protecting IT and electrical risks, it would be suitable for use for areas such as archive, gallery and artwork protection.

After review of all alternatives, IG55 was chosen as the optimum 'clean agent': -

No hazard to personnel at normal concentrations, even if trapped in room during discharge.

Electrically non-conductive.

Low container refill cost.

Genuine 'clean agent', with no agent breakdown adding to toxic or corrosive products of combustion from the fire.

No global warming potential.

Zero ozone depletion.

Absolutely no environmental disadvantages, short or long term - a genuine green alternative.

IG55 is a 50/50 mix of nitrogen and argon both of which are noble gases, chemically inert, and the mixture is approximately the same density as air. Both gasses are present in the earth's atmosphere. Additionally, for fire protection, it has the benefits of no fogging of room atmosphere upon discharge, minimal short term room cooling so avoiding condensation on equipment, and straightforward system engineering, allowing long pipe runs from cylinders to nozzle.

The enclosure should be of fire resisting construction, able to withstand the ingress of fire from outside, and of sufficient strength to retain the agent. IG55 displaces air in the enclosure and it is necessary to provide venting, which allows excess pressure relief during discharge, normally at a fairly high level in the enclosure wall. The one-way vents close at the end of the discharge, enabling the concentration to be held. In the UK, room strength is generally taken as 500 Pascal, and, for internal stud walling, 250 Pascal is taken. The venting formula in our design calculation suggests the appropriate vent area.

Once the design concentration has been achieved, standards require that it be held for not less than ten minutes, or other agreed period. Although IG55 will leak more slowly from a given enclosure than the halocarbon agents, a room integrity pressure test is still required, and leakage paths sealed if necessary. The integrity test method is detailed in the British Standard, for Gaseous Fire Fighting Systems ISO 14520.

All systems are designed within the requirements of ISO 14520, or more closely defined requirements where found in appropriate national and international standards.

Each system is carefully tailored to the risk to be protected. A risk assessment is the starting point for the protection. Is an IG55 system the best way to protect the risk? If so, is the enclosure adequate to contain the gas, or can it be made to be adequate? What materials are likely to be involved in a fire, and which require the highest concentration for extinction? What is the volume of the enclosure; is it connected to other volumes? What is the actual volume to be protected? What is the best type of detection to give early warning but minimum possibility of false alarms? Will people be present in the enclosure at a time when a fire could occur? Where is the best place to locate the system cylinders - with regard to system design, location to the fire, ease of maintenance?
Given the answers to these questions, a system can be designed, determining the quantity of gas required, the location of detectors, nozzles and distribution pipes, interlocks for doors, vents, air conditioning etc. Using well proven software, the sizes of pipes and nozzles can be readily determined, and the system designed in accordance with the appropriate standards.

IG55 systems are extremely flexible in application, and have been designed to protect enclosures of between 30m³ and 4000m³ in volume, at design concentrations of between 40 and 67.2 per cent. Up to six different enclosures have been protected from one cylinder bank, and cylinder location has been up to 80 metres from a protected enclosure.

IG55 fire extinguishing systems are protecting life, facilities and sensitive equipment, and it is of paramount importance that they retain their capabilities 24 hours a day, 365 days a year. The high quality of the system components employed goes some way towards achieving this, our engineers fully maintain systems to specification, and also re-examine the risk and check the enclosure to ensure that, if changes have been made, the leakage rates will still be within the limits for effective fire control.