The revolutionary Water-Mist technology. Low Pressure & High Pressure Water-Mist. Design calculations, Standards, Applications, Limitations. Alternative to Gas suppression - sprinkler systems. Contact: 95949-66462

1. The Revolutionary Technology
WATERMIST

2. Need of Water Mist ?
26 August 1987
11 December 1997

3. Why Water ?
Used Portion
Un-Used Portion
 1 liter of water absorbs 4.18 KJ energy to
1o
C of temp.
 It takes only 335 KJ (Kilo Joule) to heat
1 liter of water from 200
C to 1000
C.
 When turning into vapor water absorbs more
heat than any other extinguishing agent
(> 2 MJ/kg)
 In actual scenario, Water Mist droplets have
significantly increased exposure time in case of
Fire/Smoke/Airflow.
1 MM drop falls @ 1.4 m/s
50 micron drop falls @ 0.3 m/s
AtomizationAtomization
•By using the kinetic energy of
compressed air and mixed with the liquid (Water) in specially designed nozzle.

4. What is Water Mist ?
A water spray for which the Dv0.99 for the flow-weighted
cumulative volumetric distribution of water droplets, is less than
1000 microns at the minimum design operating pressure of the
water mist nozzle.

5. In the given table it is clearly observed that we can increase the surface area of
water by reducing the diameter of the droplet. For example, the water droplet
size of 12 cm gives a surface area of 0.05m2
in 1m3
volume, whereas 25 microns
droplet size gives a total surface area of 240 m2
in same volume.
Micron is a unit of measurement of length of droplet. It is also called micrometer
1 micrometer = 10-6
meter
Screening Reactivity
Surface Area Analysis

6. Classification of Mist Systems
(As per IS : 15519 / NFPA – 750)
1.High pressure – More than 34.5 bar
2.Medium pressure - Between 12.1 bar to 34.5 bar
3.Low pressure – Up to 12.1 bar
-Single Fluid & Twin Fluid

7. Type of Systems Type of Nozzles

9. Low Pressure Water Mist System -
• Low Pressure Nozzle at a pressure 12.5 bar generates mist of 100 microns at a
flow rate of 12 LPM.
• Low Pressure Systems enables to use traditional pipe network viz. copper, or
plated carbon steel.
• Suitable for local applications like transformers, generators, machineries etc..
• They are having limitation over delivery of Ultra Fine Mist particles.
• The addition of aqueous film-forming foam (AFFF) will maximize extinguishing
performance
• Economical solution compare to high pressure watermist.

10.  Water Piping & all fittings installed in low pressure water mist systems shall
conform to NFPA 13, Standard for the Installation of Sprinkler Systems &
shall be rated for the maximum working pressure to which they are exposed.
 Water mist systems shall be installed in accordance with the requirements of
NFPA 70 - National Electrical Code & All signaling system circuits and wiring
shall be installed in accordance with NFPA 72, National Fire Alarm Code
 Pipe friction losses shall be determined by using
Darcy–Weisbach Calculation Method.
Design & Testing Consideration for
Low Pressure Water Mist System

11. • By using High Pressure System, a system can generate fogging, Cooling, Humidification &
Air cleaning effect at a same time.
• Pumped systems using high pressure, Electric or Diesel driven reciprocating piston pumps
• High Pressure Systems can generate very fine particles of mist, resulting in fog formation.
• Suitable for Total flooding applications like, Museums, Metros, IT/Server Rooms. Tunnels and
undercover car parks, Re-fuelling depots and petrol stations
High Pressure Water Mist System -

12.  High pressure systems shall be permitted to be hydrostatically tested to 1.5 times the
working pressure for 10 minutes, followed by 110 minutes at the working pressure
without pressure loss.
 For dry and pre-action systems, an air pressure leakage test at 2.8 bar (40 psi) shall
be conducted for 24 hours in addition to the standard hydrostatic test.
 Fittings shall have a minimum-rated working pressure equal to or greater than the
maximum operating pressure of the water mist systems at 54°C (130°F).
 Welding and brazing alloys shall have a melting point above 538°C (1000°F) & shall
be performed in accordance with Section IX of the ASME Boiler and Pressure Vessel
Code.
Design & Testing Consideration for
High Pressure Water Mist System

13. Comparison
Sprinkler – Low Pressure &
High Pressure
Water System

14. Types of Water Mist Systems

15. Low Pressure Water Mist Nozzles
NGWP
(Net Head Multi Pairs)
NCSSFH (Colliding nozzles)
DGWP (Detection Head Multi Pairs)
1 1 1 FEN-T

16. High Pressure Water Mist Nozzles

17. Models: Single Fluid Nozzles
DGWP 15.X.Y
15 Model Number
X- Material
Type
1 stainless steel (316)
2 stainless steel (304)
3 brass (C37800)
4 brass (CuZn36Pb2As)
Y- Cap Type 0 without cap
1 silicone protection cap
Technical Parameters
Total flow
surface
12.8 mm²
Basic
extinguishing
media
Water
Net Filter
opening
0.4X0.4 mm
Droplet size Dv 65-140 μm
Connection size ¼” BSP int
Inlet pressure 6-16 bar
Number of holes
ring
1
Head weight 0.5 kg
Protection cap Cat No.- N 118
Heat Sensitive
bulb
Orange- 57o
C/RTI- 22ms
Applications Local Application & Total
Flooding

18. Models: Twin Fluid Nozzles
The Twin Fluid Nozzles have a
typical nomenclature of A B C
FEN- T, where:
•A= Number of water jets
•B= Number of air jets
•C= Air flow [m³/min]
•FEN= Flame Effective
Neutralization
•T= Temperature: Elevated
temperature resistant
1 1 1 FEN-T
• 1 - Number of water jets
• 1 - Number of air jets
• 1 - Air flow [m³/min]
Water Mist head weight 0.4 kg
Range of Effective Mist Stream 2.5 m
Maximum Range of Mist Stream 3.5 m
Working temperature 10 – 700 O
C
Application Fire Suppression
Droplet Diameter 4 to 200 microns

19. Application
Water Mist

22. Standards for Designing Water Mist
Standard Title
NFPA 750
National Fire Protection Association American Standard on Watermist Fire Protection
Systems
IS 15519 Indian Standard for WaterMist System design, installation & commissioning.
FM5560 Factory Mutual American Standard for WaterMist Fire Protection Systems
UL2167 Water mist Nozzles for Fire Protection Services
EN TS 14972 European Technical Specification for Fixed Firefighting Watermist Systems
IMO A800 International Marine Organisation Standard for Watermist Systems
BS 5839 – Part 1: 2002
(as amended)
Fire Detection and Alarm Systems for Buildings
BS 7671 Requirements for electrical installations – IEE Wiring Regulations – Seventeenth edition
BS 7273-3
Code of practice for the operation of fire protection measures – Part 3: Electrical actuation
of pre action watermist and sprinkler systems
BS EN 1057
Copper and copper alloys – Seamless, round copper tubes for water and gas in sanitary
and heating applications
BS EN 1968
Transportable gas cylinders – Periodic inspection and testing of seamless steel gas
cylinders
BS EN 15004-1: 2008
Fixed firefighting systems. Gas extinguishing system. Part 1: Design, installation an
maintenance

23. Limitations of Water Mist :-
The systems shall not be used for direct application to materials that react with
water to produce significant amounts of heat or hazardous products.
These materials include the following:
Reactive metals, such as lithium, sodium, potassium, magnesium, titanium,
zirconium, uranium and plutonium, etc.;
Metal alkoxides, Carbides, Halides, Hydrides, Oxyhalides, Silanes, Sulfides,
Cyanates,
Systems shall not be used for direct application to liquefied gases at cryogenic
temperatures ( such as liquefied natural gas - LNG ) which boil violently when
heated by water.

24. Thank
You…
Prepared By,
Mr. Akshay Jangam.