Very similar characteristics to Halon 1301 but with Zero ODP makes this EPA
approved gas the most effective replacement for current Halon installations.
Ratio of propellant (nitrogen) to agent means that most halon systems will be
able to retain the original pipe work.
(Check with us for system calculations)
NAF S 125 is identified as HFC 125 in the international standards. It is a clean
agent particularly indicated for total flooding applications and requires the
lowest concentration by weight among all the zero-ODP halo carbon agents.
Thanks to its physical characteristics, very similar to those of Halon 1301, NAF
S 125 can be used also for the protection of low-temperature risks. With a
boiling point of -48.5 °C, NAF S 125, in fact, is quickly distributed inside the
protected environment. Used in the military fighters of the US Air Force, it is
considered by the US Federal Aviation Authority one of the best alternatives to
Halon 1301 for cargo bays and engine nacelles of commercial airliners.
Thanks to its low acute toxicity, NAF S 125 can be used for the protection of
normally occupied areas. The NAF S 125 maximum exposure times at different
concentrations have been determined with the US EPA-approved PBPK model. In the
NFPA 2001 Standard (Edition 2000), the maximum safe exposure of NAF S 125 has
been set up at 11.5% for 5 minutes
PYROSHIELD is an inert gas blend of two gasses that are both naturally occurring
elements in the air we breathe. These two gases have different molecular weights
but when mixed have a similar molecular weight to normal air, greatly increasing
the hold times.
Upon discharge, PYROSHIELD will reduce the oxygen level below the point at which
combustion can take place whilst still being safe to personnel.
PYROSHIELD has zero ozone depletion potential (ODP), zero global warming
potential and no secondary products of combustion. Additional benefits are that
PYROSHIELD is a clear, odorless gas which produces no obscuration, has a low
refill cost and cylinders can be stored remotely from the risk. This makes
PYROSHIELD ideal for switch rooms, process industry, control rooms and
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.
PYROSHIELD 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
Once the design concentration has been achieved, standards require that it be
held for not less than ten minutes, or other agreed period. Although PYROSHIELD
will leak more slowly from a given enclosure than the halo carbon 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
Each system is carefully tailored to the risk to be protected. A risk assessment
is the starting point for the protection.Is an PYROSHIELD 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.
PYROSHIELD 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.
Suppresion System Control room
Example of How a Suppresion system function