1. Liquid Nitrogen (LN2) Fire Extinction - Phase II
Dennis Bernal, Paul Brownsey, John Falkowski,
Chris Forrest, Josh Miranda
Client: Professor Levendis
Chris
NEU Engineering Co.
Inspired Innovation

2. Background
Prof. Levendis has developed a fire extinction technique using the direct application of the cryogen Liquid Nitrogen (LN2) to fires
This technique has been validated through testing on liquid pool fires about 1m2 in area; the results of which were recently published in the journal of the Fire Protection Association (FPA)
Chris

3. LN2 Characteristics Nitrogen boils at 77K Displaces oxygen molecules
Environmentally benign
Atmosphere contains 78% nitrogen
Cost efficient ($0.75/gallon)
Josh

4. Video used with permission, © 2008 Y. Levendis
Client’s Testing
Tests conducted by our client at the Commonwealth Scientific and Industrial Research Organization (CSIRO) National Laboratories in Australia
Josh
Video used with permission, © 2008 Y. Levendis

5. Problem Statement Evolution
Our client wishes to have a device for applying liquid nitrogen from a distance, to fires of 10 m² in area and eventually 100 m²
A previous consulting firm determined that a feasible and effective concept of delivering liquid nitrogen to a small fire is by a hose and nozzle. This concept was validated through construction of a bench scale prototype and conduction of small laboratory tests
Josh
Previous Firm’s Prototype

6. Current Problem Statement
Make the new system safe and easy to use
Have “dead man” valve to prevent dropping accidents
Pressure relief valve to guarantee safe use near fire as well as after shut-off
Our task is to design a commercial hose and nozzle delivery system that is cost effective and proven to work
This will take extensive field testing
Use of as many commercially available parts as possible to reduce cost
Careful material analysis and selection
Josh
Provide the client with a way to deliver liquid nitrogen to a fire from a safe distance.

7. Design Specifications
Fire Area
Application method
Amount of LN2
1 sq meter
Manual application
(as demonstrated in video)
½ liter of LN2,
Few seconds to extinguish
10 sq meters
Hose application desired
13 m horizontal distance (10 m to edge of fire, plus 3 m across area of fire)
5 liters x FOS of 2 = 10 liters in 10 seconds
Desired flow rate 1 liter/s
100 sq meters
(future consideration)
Bulk Delivery of LN2
50 liters x FOS of 2 = 100 liters in 100 seconds
Josh

8. Design Considerations
Weight
Must be equal to or less than a standard water nozzle currently used by fire department
Size
Comfortable and similar in size to current water nozzle (46cm)
Safety of User
Insulated Housing
“Dead Man” Release Mechanism
Pressure Relief Valve
Cool Down Period
Minimize time for nozzle and hose assembly to cool before LN2 fires
Dennis
Traditional Water Nozzle
8.1 kg (17.9 lbs)

9. Overall Design Concept
Custom Designed Nozzle
Cryogenic Ball Valve
Reducer
Protective Housing
Vacuum Jacketed Supply Hose
Truck
Storage Tank
Cryogenic Pump
Flow Control/Monitoring
Dennis

10. (Dead-Man Mechanism)‏
Recommended Design
Torsion Spring
(Dead-Man Mechanism)‏
Linkage & Handle
Cryogenic
Hose
Housing
Ball Valve
Extender
Nozzle
Dennis

11. Difference in Thermal Expansion between materials: 0.017 [mm]
Red Brass (85% Cu – 15% Zn)
Stainless Steel (Type 316)
[1/K]
[1/K]
L = Wall thickness
Tfinal – Tinitial = K
[meters]
[meters]
John
[meters]
[meters]
Difference in Thermal Expansion between materials: [mm]

12. John

13. COSMOS - Nozzle (Time = 300 sec.)
163 K
125 K
John
90 K

14. John

15. COSMOS - Hose (Time = 300 sec.)
300 K
190 K
78 K
John
125 K

16. Test Specifications and Setup
Test Goals
Prove that N2 can be shot and stay in liquid form through air
Shoot LN2 10 meters
Extinguish a fire from 10 meters
Test Variables
Supply pressure
Orifice Size
Nozzle Angle
Tests were visually recorded with digital cameras and camcorders
Measured Values
Cool Down Time
Size of gas plume
Throw Distance
Time to extinguish fire
Cryogenic ball valve effectiveness
Chris
Supply pressure – Tested in a range of 62 kPa to 517 kPa
Nozzle Size – Two different orifice sizes (3.3 mm and 4.2 mm), and no nozzle tip (just the reducer opening 13.9 mm)
Nozzle Angle – 45 degrees from horizontal, and between 0 and 15 degrees

17. Test Photos
Setup: 3m hose, brass ball valve, extender, 12.7mm nozzle opening
Time – 0 sec
Fire is lit at 4.88m
Chris
Time – 7 sec
GN2 & LN2 reaches fire
Time – 36 sec
Liquid nitrogen boils in fire
Time – 90 sec
Fire is completely extinguished

18. Test Results and Conclusions
Cool down time to steady state
120 seconds (3.3 m hose)
150 seconds (7 m hose)
Plume
Ball Valve Effectiveness
Ability to shoot liquid nitrogen a distance
Fire Extinction
Chris
Found to be narrow enough that cone is not needed
On/Off control – instant liquid at nozzle tip
Max distance achieved with prototype: 6.1 meters

19. Flow Optimization Unique considerations for cryogen flow
Large pressure drops cause flash vaporization
As fluid vaporizes pressure and velocity increase
Test data was used to develop assumptions to calculate flow characteristics for larger systems
Paul

20. Final Nozzle Design Recommended Specifications LN2:GN2 Distance
Low Pressure
High
Short
High Pressure
Low
Long
Paul
Recommended Specifications
1” Vacuum jacketed supply hose
~3/4” Nozzle orifice

21. Cost Analysis Prototype BOM Actual Design BOM Component Qty Price per
Total Price
Component
Qty
Price per
Total Price
304 SS 1/2" ID NPT coupler 2
$4.81
$9.62
304 SS 1" ID NPT coupler 2
$11.18
$22.36
304 SS 1/2" ID NPT reducer 1
$6.31
$6.31
304 SS 1" ID NPT/welded to 3/4" reducer 1
$18.14
$18.14
304 SS 1/2" ID NPT 5"L extender 1
$16.86
$16.86
304 SS 1" ID NPT 4"L extender 1
$6.39
$6.39
Housing pipe and couplers 1
$99.78
$99.78
Housing pipe and couplers 1
$99.78
$99.78
32 in-lb torsion springs 2
$11.03
$22.06
1/2" ID bushings 2
$1.89
$3.78
32 in-lb torsion springs 2
$11.03
$22.06
Cryogenic brass ball valve 1/2" NPT 1
$260.41
$260.41
1/2" ID bushings 2
$1.89
$3.78
Paul
5/8" ID Semiflex hose - 10 ft 1
$0.00
$0.00
40' Semiflex 1" ID hose, safety relief valve, cryogenic ball valve 1
$4,446
$4,446
Safety relief valve - 1/2" NPT 1
$0.00
$0.00
Welding 2
$75.00
$150.00
Welding
0.5
$75.00
$37.50
Machining
1.5
$75.00
$112.50
Machining
1.5
$75.00
$112.50
Prototype Total Cost:
$568.82
Design Total Cost:
$4,881

22. Recommendations Nozzle Optimization
Find relationship between supply pressure, hose size and orifice size – to maximize flow, for a decent distance.
Re-design consideration for larger fires
A system that dumps a large amount of LN2 at once
Paul

23. Questions?
Paul