Engineering Performance of Water Mist Fire Protection
Systems with Antifreeze Solutions
Jeff Rosen (ME), Michael Szkutak (CHE), Matt Connolly (ME ), Stephen Jaskolka (CHE)
Advisor: Professor Kathy Notarianni (FPE), Professor David DiBiasio (CHE)
Spray Performance and Standby System Results
Abstract
Background and Previous Research
Research Plan
Test Cell Diagram for Fire
Scenario Interactions
Solution Concentrations to Benchmark Freezing Points (wt.%)
Propylene Glycol (PG)
Glycerine (Gly)
Betaine (B)
Concentration
to -20°C
40%
48%
41%
Potassium Acetate (KA)
28%
Concentration
to -40°C
55%
63%
53%
4 ft. of ½ in.
304 Stainless Steel
Ball
Valve
21 ft. of
½ in.
Hydraulic Hose
1 ft x 2 ft.
Propane
Diffusion
Burner
Ball Check
Valve Valve
Water
Source
Pressure
Washer
Ball
Valve
Drain
200
Potassium Acetate - 39wt%
Betaine - 53wt%
150
Glycerine - 63wt%
100
Summary of Key Study Variables
50
High
-40 -35 -30 -25 -20 -15 -10 -5 0
Temperature (°C)
5
10
15
20
25
Low
Average HRR with Water Discharge vs. Time
ß 8 ft. à
Viscosity
Density
Water
Betaine
Glycerine
K Acetate
P Glycol
Glycerine
P. Glycol
Betaine
K Acetate
Water
K Acetate
Glycerine
Betaine
P Glycol
Water
High Pressure Qualitative Observations
Expansion
Coefficient
P Glycol
Glycerine
Betaine
K Acetate
Water
Corrosivity
Betaine
K Acetate
P Glycol
Glycerine
Water
Summary of Non-dimensionalized HRR Peaks
H20
Low Pressure
KA(-20C)
High Pressure
KA(-40C)
PG(-20C)
Pre-discharge Fire
• Region 1 is the pretest, fire ignition, and fire growth
period
• Region 2 is the discharge period of both antifreeze
and water
• Region 3 is the re-establishment the fire after
discharge termination
• Region 4 is the fuel source termination and post-test
venting
H20
PG (-40ºC)
PG(-40C)
Gly (-20C)
Gly (-40C)
B (-40C)
0
B (-40ºC)
Gly (-40ºC)
• High concentrations of potassium acetate and betaine should be limited in application
due to corrosivity concerns with system materials.
• High pressure, high concentration solutions of propylene glycol, glycerine, and betaine
have flammability and ignition concerns.
• All concentrations at low pressure, and high pressure, low concentration solutions of
propylene glycol, glycerine, and betaine showed a less significant change in HRR and
may be considered for use in water mist systems.
Propane
Source
Surface Tension
Fire Scenario Interaction Results
• High concentrations of propylene glycol and glycerine experience exponential increases
in viscosity as the temperatures approach the solution’s freezing point.
Standard
Compartment
Standby System Concerns
• Corrosion
• Volumetric Expansion
Propylene Glycol - 55wt%
Conclusions
Pressure
Gauge
39%
Spray Performance Variables
• Viscosity
• Density
• Surface Tension
Fire Scenario Interactions
• Heat Release Rate (HRR)
• Qualitative Observations
Fill
Area
ß 8 ft. à
Base Fluid
250
0
Comparisons of Water Mist and Traditional Sprinklers
• Water mist systems were introduced in the System Property
Water Mist
Traditional Sprinklers
1940s
Droplet Size
Less than 1000 microns
Between 1 and 5 millimeters
• NFPA 750 defines a water mist discharge Operating Pressure Less than 175 psi to
At least 7 psi
greater than 500 psi
as a spray where 99% of the droplets
Volumetric Flow Rate Between 2 and 10 gpm Approximately 30 gpm
cannot exceed a nominal diameter of
Nominal Pipe
Between ½” and 2”
Between 2” and 6”
Diameter
1000 microns
Stainless steel and
Stainless steel, copper alloys,
• Primary advantage of water mist is the
Pipe Material
copper alloys
and plastics
reduced water demand
Antifreeze Suppression Accidents
• In 2001, a traditional sprinkler system, protected with a propylene glycol solution, activated and injured
19 people.
• In 2009, a traditional sprinkler system, protected with a 70% glycerine solution, activated and
contributed to a fatal explosion in a kitchen fire.
Research Involving Antifreeze
• Propylene glycol not exceeding 38% by volume and glycerine not exceeding 48% by volume are
permitted to be installed in new traditional sprinkler systems.
• Salt antifreezes have been found to decrease the energy contribution to a fire, relative to water.
Antifreeze Selection
• Based on the theorized effects of liquid properties, tested solutions should have:
o Larger droplets at higher viscosities than water
o Smaller droplets at higher densities than water
o Smaller droplets at lower surface tension than water
• Results predict opposing droplet size effects, but the exponential increase in viscosity with lower
temperature will likely dominate the three properties
• The combination of corrosion and volumetric expansion may lead to system failures over time by
leaking or pipe bursting
o Antifreeze solutions were more corrosive to copper samples than stainless steel samples
o All antifreeze solutions expand more than water and expansion vessels may be required
Kinematic Viscosity Relative to Water at 4oC for
Antifreeze Solutions Freezing at -40oC
Relative Kinematic Viscosity (-)
The integration of antifreeze into water mist systems raises performance concerns based on the smaller
droplet sizes and higher discharge pressures relative to traditional sprinkler systems. Antifreeze of various
chemical compositions and concentrations were evaluated based on variables affecting the following
categories: spray performance, standby system design concerns, and the fire scenario
interactions. Extensive testing demonstrated that no antifreeze solution behaves ideally when analyzed
with respect to all three categories of variables. High pressure, high concentration solutions of certain
antifreezes should be avoided due to flammability and ignition concerns. The impact of all other tested
pressures and concentrations on the heat release rate of the fire was less significant, and these solutions
may be considered for use in water mist systems. Solution flammability was proven to be a function of
solution concentration and droplet size. Future testing should focus on droplet size to more definitively
prove the feasibility of using antifreeze in water mist systems.
• At all pressures and concentrations, solutions of potassium acetate had the most
significant reduction of the HRR or caused extinguishment.
• At all pressures and concentrations, solutions of glycerine present a potential life safety
hazard due to excessive smoke production.
0.5
1 1.5 2 2.5 3 3.5
Normalized HRR Multiplier
4
4.5
KA (-40ºC)
Acknowledgments
We would like to thank the following individuals:
• Professor Kathy Notarianni
• Jack Mawhinney
• Professor David DiBiasio
• Jack Ferraro
• Adam Tracy
• Randall Harris
References
Arvidson M. Flammability of antifreeze agents for automatic sprinkler systems. Journal of Fire Protection Engineering 2011;
Vol. 21(2): 115-132.
Burke T and Ferrugia J. Antifreeze in fire sprinklers can fuel flames: 27-year-old mother killed in flash
fire, http://www.thedenverchannel.com/news/26891935/detail.html (2011, accessed 12 November 2011).
Code Consultants Inc. Antifreeze solutions in home fire sprinkler systems: phase II research final report. Report, Quincy, MA, USA: Fire
Protection Research Foundation 2010.
Howard G. Report: Antifreeze sprinkler system may have contributed to fatal explosion. Sierra Sun, 16 October 2009.
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NFPA 750. Standard on Water Mist Fire Protection Systems. NFPA 750, Quincy, MA, USA: National Fire Protection Association, 2010
edition.