The fire prevention powder Impulse Storm, specially designed for use in these cases, is an unique powder with bulk weight of 0,2 g/cm³. The powder is not a chemical synthesis product – it consists of very stable natural components which do not chemically react with any other substance. As a result, the powder sprayed by the Impulse Storm technology into the tunnel will play an important role as a fire agent, even after the extinguishing is made. The powder can be stored in a shaft for unlimited number of years without losing its fire prevention properties and causing no harm to cables or environment. This powder does not cohere or turn into a solid mass, and it can be removed anytime, even in 10 or 20 years. It is recommended that the powder is left in the tunnel, serving as neutral filler, and in case of an eventual ignition, it will play an important role in preventing fire development. In summary, it is possible to fill narrow cable tunnels with the Impulse Storm powder immediately after its construction. The easiness, big volume, low mass, and low cost of the powder allow such application.

1. FIRE IN TUNNELS
Modern techniques for designing and constructing tunnels permit a detailed analysis of the
different fire risks and the possible means for detecting and extinguishing these fires.
This allows creating an ideal symbiosis in tunnel construction: involving existing power
structure and fire detection and extinguishing at initial stages; raising considerably the tunnel’s
safety level. However, unfortunately, there are several tunnels where with enormous quantities
of electric cables, with different purposes and occasionally belonging to different owners.
Voltage and current strength in these cables are not always known and they cannot be cut off
from a single command panel. As a result, is not possible to extinguish fires in such tunnels with
conventional water or foam systems, nor the use of volumetric extinguishing methods can be
applied, due to the big volumes involved and the existence of ventilation.
Subways are such tunnels.
In modern times, when negative factors of anthropogenic, environmental and terrorist nature
aggravate, it becomes particular important to enhance subway fire protection, once big fires
may cause mass mortality and transport collapse of a city.
Fires in underground transportation structures and tunnels are characterized by quick
spreading of dangerous substances, fast temperature raising, blocking of escape routes,
contamination of adjacent surface areas and buildings with toxic products result of the fire,
damage of tunnels’ structures, and interruption of important traffic artery.
Fire development in subway train cars, on passenger platforms, escalators, tunnels and subway
objects, which are critically important for safety, has essential peculiarities, such as:
• semi-confined areas with significant concentration of people, associated with the
complexities of passenger evacuation;
• high possibility of burning of materials that discharge toxic components when burning;
• presence of a power cables with voltage of up to 10 kW;
• presence of a considerable number of electric installations under voltage, including the
train cars;
• high air exchange speed causing fast increase of temperature to the values of over one
thousand degrees.
After three or five minutes the fire starts, the situation becomes critical, due to the usual
concentration of people in the tunnel. In such situations, people must be immediately
evacuated from the tunnel, and the following situations may occur:
• possibility of dense smoke on escape ways;
• great difficulties, and in several occasions, it may be virtually impossibility to supply
required volumes and flows of fire extinguishing substances to fire centers;
• likelihood of panic among passengers.

2. The specific characteristics of the fires on underground objects and in tunnels, demand strict
and specific requirements to fire extinguishing systems, in particular:
• fire extinguishing substances used in rail wagons, on passenger platforms and escalators
must be safe for people;
• the system should secure quick performance, including cases in which maneuvering is
restricted in the tunnel;
• the fire extinguishing system should secure safety for the people present in rail wagons,
on platforms and escalators,
• the fire liquidation task should not lead to flooding of subway tunnels, cable trays, and
engineer premises.
The impulse powder fire extinguishing technology “Impulse Storm” allows solving most of the
problems involved on fire extinguishing in specific conditions on subways. This article briefly
presents the advantages of the Impulse Storm technology in two particular examples.
CASE 1: UNEXPECTED IGNITION OF ELECTRIC CABLES OR CONTACT RAILS
Old subway tunnels, built several of dozens of years, have several energized cables with a
variety of purposes
such as communication and electric power supply cables. Furthermore, there are occasions in
which cables interconnect objects belonging to third parties, with unknown electric current and
voltage intensity, and without fast possibilities for disconnecting in case of urgent
requirements. Subway train conductors are usually the first persons who detect a fire that
emerged in the result of a short circuit in a cable or in a contact rail. One may think that the
initial, simplest and easiest action should be having the conductor stop the train, take a fire
extinguisher, and extinguish the burning cable before the neighboring cables insulation catches

3. on fire and the fire evolves to an uncontrolled stage. However, in reality, this is impossible to
do, due to several reasons:
• one cannot approach the area of a short circuit in less than two meters, in order to
avoid electric shock.
• it is prohibited to use water or water-and-foam fire extinguishers.
• Due to the distance from the ignition center, the use a carbon dioxide or other gas fire
extinguishers is inefficient. Some energized cables can be disposed at heights reaching
up to 5 meters from the floor level.
These three points are also applicable for cases when a fire happens under train cars and in a
contact rail.
The existing fire extinguishers occupy reasonable areas in the conductor’s cabin and often
cannot be applied because of their heavy weight.
The problems involved with the requirements of instantaneous extinguishing of cable ignitions,
rail wagons space and contact rail are solved by using the “EDDY extinguishers”, a hand-held
Impulse Storm technology fire extinguisher
With its small weight (up to 1 kilogram) and dimensions (not exceeding a police baton), these
extinguishers can be fixed to walls or even on the structure of a subway cab These fire
extinguishers have a range of effective action reaching up to 12 meters in vertical or horizontal
planes, allowing the extinguishing in any place within a tunnel, irrespective of existence of
electricity of any voltage or current strength. Numerous tests carried out in subways of Kiev
(Ukraine), Moscow and Saint Petersburg (Russia) have shown that currently the Eddy is the only
fire extinguisher that can be effectively and safely used for extinguishing ignitions on electric
cables or other electric objects under voltage.

4. Hand-held fire extinguishers - Eddy can be used in a one-barrel configuration and in a multi-
barrel variant

5. , either by conductors, security personnel or firemen. The Eddy fire extinguishers have a long
shelf life, requiring little servicing, and can be used even after 10 years of storage. These
extinguishers can be simply disposed on tunnel walls in certain intervals and can be left
unattended for many years, until a fire happens, and any person who finds himself near can use
the extinguisher.
One of the most valuable properties of the Impulse Storm technology upon extinguishing fires
in tunnels is that there is no need to turn off the electric power. The Impulse Storm technology
has been tested in currents over 50,000 Volts, and can be used in much higher voltages.
As an example, in 1995 during a fire in a subway in the city of Baku, capital of Azerbaijan, 289
people died as a result of power cut off, solution adopted to secure a possibility for fire
extinguishing. Unfortunately, the fire was not extinguished, and a train, with its passengers,
was caught in a fire trap. Even though the evacuation plan was activated, on the escape route
to the nearest station, people died as a result of high temperatures and poisonous products
from the burning process. If the Impulse Storm technology was used, there would be no need
to cut off the power, allowing to drive the train to the nearest station, and securely evacuate
the passengers.
CASE 2: NARROW CABLE TUNNELS
The problem of extinguishing fires on electric cables in narrow tunnels is commonly known.
Usually, a man cannot get through these tunnels; water and water-and-foam fire extinguishers
cannot be used until electricity is cut off; and the use of volumetric gas or aerosol extinguishing
means will be ineffective due to ventilation systems. The Impulse Storm technology in fire
extinguishers specially designed for use in narrow tunnels can instantly put out a fire, reaching
distances up to 50 meters from the extinguisher. The extinguishing on these tunnels is

6. performed by instantly spraying a mixture of a highly-concentrated cloud of neutral gas and a
special one-component powder. The speed of the sprayer cloud on the tunnel’s channel can
reach 100 meters per second. The high impact action of the cloud on the flame will
immediately knock down the flame, and the powder will immediately extinguish, bind and
cover the melting plastic cable casings and prevent re-ignition. Considering that the casings of
modern cables either do not burn at all, or burn without smoldering, i.e. only vapors of the
melting casing burn, the Impulse Storm technology is the only technology with true possibilities
to extinguish fires in inaccessible narrow cable tunnels without having to cut off the electricity.
The fire prevention powder Impulse Storm, specially designed for use in these cases, is an
unique powder with bulk weight of 0,2 g/cm³. The powder is not a chemical synthesis product –
it consists of very stable natural components which do not chemically react with any other
substance. As a result, the powder sprayed by the Impulse Storm technology into the tunnel
will play an important role as a fire agent, even after the extinguishing is made. The powder can
be stored in a shaft for unlimited number of years without losing its fire prevention properties
and causing no harm to cables or environment. This powder does not cohere or turn into a solid
mass, and it can be removed anytime, even in 10 or 20 years. It is recommended that the
powder is left in the tunnel, serving as neutral filler, and in case of an eventual ignition, it will
play an important role in preventing fire development.
In summary, it is possible to fill narrow cable tunnels with the Impulse Storm powder
immediately after its construction. The easiness, big volume, low mass, and low cost of the
powder allow such application.
New Impulse Technologies (Russia) and Merco Shipping (Brazil) are ready to demonstrate the
Impulse Storm technology on prepared proving grounds in Russia, Ukraine or Brazil anytime.