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Significant New Alternatives Policy Program

Fire Extinguishing and Explosion Prevention Sector

Risk Screen on Substitutes for Halon 1301

Total Flooding Systems in Occupied and Unoccupied Spaces

Substitute: K-Ace

This risk screen does not contain Clean Air Act (CAA) Confidential Business 

Information (CBI) and, therefore, may be disclosed to the public.

1. INTRODUCTION

Ozone-depleting substances (ODS) are being phased out of production in response to a series of 

diplomatic and legislative efforts that have taken place over the past two decades, including the Montreal 

Protocol and the Clean Air Act Amendments of 1990 (CAAA). The U.S. Environmental Protection 

Agency (EPA), as authorized by Section 612 of the CAAA, administers the Significant New Alternatives 

Policy (SNAP) Program, which identifies acceptable and unacceptable substitutes for ODS in specific 

end-uses based on assessment of their health and environmental impacts.

EPA’s decision on the acceptability of a substitute is based on the findings of a screening assessment of 

potential human health and environmental risks posed by the substitute in specific applications. EPA has 

already screened a large number of substitutes in many end-use applications within all of the major ODSusing sectors, including refrigeration and air conditioning, solvent cleaning, foam blowing, aerosols, fire 

suppression, adhesives, coatings and inks, and sterilization. The results of these risk screens are presented 

in a series of Background Documents that are available in EPA's docket.

The purpose of this risk screen is to supplement EPA’s Background Document on the fire suppression 

and explosion protection sector (EPA 1994) (hereinafter referred to as the Background Document). This 

risk screen discusses the potential human health and environmental risks posed by K-Ace when used as a 

flooding agent in normally occupied spaces as a replacement for Halon 1301. The reader is referred to the 

Background Document for the methodologies and assumptions used to conduct this risk screen. 

K-Ace is being proposed for a range of applications, including commercial applications, but primarily 

military vehicle applications. The K-Ace system typically consists of a one-gallon cylinder of the 

proposed substitute, controlled by a dispensing nozzle that releases the proposed substitute in 0.042 to 

555 micron-sized droplets (average 39.3 microns) at a <90° cone spray pattern. In order to suppress fires, 

the extinguisher discharges K-Ace over a period of 3 to 4 minutes, at a rate of 20 to 80 grams/second.

Table 1 presents the composition of the proposed substitute.
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Table 1: Composition of K-Ace

Constituent Chemical 

Formula CAS No. Percent of Total (by weight)

Potassium Acetate C2H3KO2 127-08-2 50%

Water H2O 7732-18-5 50%

UL listing for K-Ace systems in military applications is not being sought, although the proposed 

substitute is anticipated to be primarily used for Class A (ordinary combustibles) and Class B (flammable 

liquids and gases) fires. Other potassium acetate formulations similar to K-Ace are currently used in other 

applications, such as commercial kitchen fire protection.

Section 2 of this risk screen summarizes the results of the risk screen for the proposed substitute. The 

remainder of the risk screen is organized into the following sections:

• Section 3: Atmospheric Assessment; 

• Section 4: Potential Health Effects;

• Section 5: Occupational Exposure Assessment; 

• Section 6: End-Use Exposure Assessment; 

• Section 7: General Population Exposure Assessment; 

• Section 8: Volatile Organic Compound Assessment; and

• Section 9: References.

2. SUMMARY OF RESULTS

K-Ace is recommended for SNAP approval as a flooding agent in normally occupied spaces. Given that 

proper training will be provided to personnel and that appropriate personal protective equipment (PPE)

and proper procedures according to the MSDS (including provision of adequate ventilation) will be used 

during installation, maintenance, and disposal activities, no significant risks to workers or the general 

population is anticipated. Section VIII of the Occupational Safety & Health Administration (OSHA) 

Technical Manual (OSHA 1999) should be consulted for information on selecting the appropriate types of 

PPE. Additionally, the risk screen indicates that the use of the proposed substitute will be less harmful to 

the atmosphere than the continued use of Halon 1301 and substitutes used in this sector, such as HCFC 

Blend A, HFC-227ea, and HFC-125. 

3. ATMOSPHERIC ASSESSMENT

This section presents an assessment of the potential risks to atmospheric integrity posed by the use of KAce as a flooding agent. K-Ace contains no Class I or Class II ODS, nor any compounds with a measured 

global warming potential (GWP). Therefore, the use of K-Ace will be less damaging to the atmosphere 

than continued use of Halon 1301, which has a GWP of 7,140 (Forster et al. 2007) and an ozone depletion 

potential (ODP) of 15.9 (WMO 2011). Furthermore, K-Ace has a significantly lower impact on the 

climate than other substitutes used in this sector, such as HCFC Blend A, HFC-227ea, and HFC-125, as 

shown in Table 2.
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Table 2. Atmospheric Impacts of K-Ace Compared to Other Flooding Agents

Chemical Ozone Depleting Potential 

(ODP)

Global Warming Potential

(GWP)

Atmospheric Lifetime 

(ALT) in Years 

K-Ace 0 0 0

Halon 1301 15.9a 7,140b 65b

HCFC Blend Ac 0.035ad 1,546b NAe

HFC-227ea 0 3,220b 34.2b

HFC-125 0 3,500b 29b

a WMO (2010) 

b IPCC 4th Assessment Report (Forster et al. 2007) c HCFC Blend A is a blend consisting of HCFC-123 (4.75%), HCFC-22 (82%), HCFC-124 (9.5%), and D-limonene (3.75%). d WMO (2007)

e NA= not available. Atmospheric lifetimes are not given for blends because the components separate in the atmosphere. The ALT for HCFC123 is 1.3 years, HCFC-22 is 12 years, HCFC-124 is 5.8 years, and D-limonene ranges from less than a minute to a few hours (IPCC 4th 

Assessment Report [Forster et al. 2007] and WHO 1998).

4. POTENTIAL HEALTH EFFECTS

According to the MSDS, K-Ace is not a primary ocular, respiratory, or skin irritant, and is not considered 

to be orally toxic. However, K-Ace may irritate the eyes and cause prolonged impairment of vision if it is 

directly in contact with the eyes for an extended duration. If contact with eyes occurs, immediately flush 

the eyes with water for at least 15 minutes, holding the eyelids open; contact lenses should be removed, if 

worn. Inhalation is not expected to pose a risk. In the case of dermal exposure, the skin should be rinsed 

with soap and water. Excessive ingestion (>25 grams) of K-Ace may irritate the digestive tract, resulting 

in nausea, vomiting, and/or diarrhea; in sensitive populations, muscular weakness, burning, tingling and 

numbing sensations of hands and feet, reduced blood pressure, irregular or slower heartbeat, and cardiac 

arrest may also occur. Should K-Ace be ingested, the person should drink water or milk; vomiting should 

not be induced unless directed by medical personnel. If medical advice cannot be obtained, the person 

should be brought to a medical emergency treatment center or hospital. Because the PPE 

recommendations outlined in the MSDS for K-Ace and Section 5.2 of this risk screen are followed, these 

potential health effects are unlikely to occur.

5. OCCUPATIONAL EXPOSURE ASSESSMENT 

The potential for personnel exposure during manufacture, installation, and maintenance are examined in 

this section. Discharge scenarios discussed are assumed to occur accidentally and not as the result of a 

fire. In order to evaluate occupational exposure, EPA has evaluated the active compound contained in KAce, potassium acetate. This compound exhibits low toxicity and has been approved by the U.S. Food 

and Drug Administration (FDA) for injection to treat diabetic ketoacidosis (FDA Application No. NDA 

018896). Further information on the common application types, FDA approval status, and associated 

hazards for this compound are presented in Table 3. 

Table 3: Common Applications Types and FDA Approval Status of Potassium Acetate

Constituent Common 

Application Types FDA Approval Statusa,b Associated Hazards

Potassium acetate

- Food

- Pharmaceuticals

- Textiles

- FDA-approved as synthetic flavoring

(21 CFR 172.515)

- Minor eye irritation

- Minor skin irritation

- Minor respiratory tract irritation

- Gastrointestinal discomfort a FDA = U.S. Food and Drug Administration

b FDA approvals are subject to use restrictions. Please see the cited regulation for further information.
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5.1. Occupational Exposure during Manufacture

K-Ace is not expected to pose a risk to workers during manufacture. As indicated by the submitter, K-Ace 

is handled in a closed system from the time it is received by the submitter until it is shipped out in filled 

cylinders. Specifically, 300 gallons of K-Ace is received at the facility as a liquid in totes which are then 

elevated on a rack. Cylinders are then gravity-filled from the totes through a solenoid valve controlled by 

a flow meter. Once filled, the valve assembly is installed, the cylinder pressurized and assembly leak 

checked, and then the cylinders packed and stored in a carton on a pallet (Amerex 2012). Since the 

manufacturing process is a closed system with no direct handling of agent, occupational exposure during 

manufacture of K-Ace is not expected to occur and EPA believes that manufacture of K-Ace does not 

pose a significant risk to human health. 

5.2. Occupational Exposure during Installation and Maintenance

K-Ace is not expected to pose a significant risk to personnel during installation and maintenance 

activities, even in the case of an inadvertent discharge of the entire charge. In such cases, the proposed 

substitute will discharge and settle as a water mist, and as a result, significant oxygen displacement is not 

expected to occur. In addition, as noted above, potassium acetate, the only active ingredient of K-Ace,

exhibits low toxicity and is commonly used in food, pharmaceutical, and textile applications. For 

measures designed to minimize the hazards associated with K-Ace, the proposed substitute’s MSDS 

should be referenced. In order to protect workers from exposure, EPA has outlined the following 

recommendations in accordance with established good manufacturing practices:

• Training for safe handling procedures should be provided to all employees that would be likely 

to handle the containers of K-Ace or extinguishing units filled with the material;

• All employees handling the proposed substitute wear PPE selected in accordance with the 

OSHA Technical Manual.

• Adequate ventilation should be in place, 

• All spills should be cleaned up immediately in accordance with good industrial hygiene 

practices.

By adhering to safety guidelines, the potential for worker exposures to K-Ace during installation and 

maintenance will be unlikely. It is recommended that the proposed safe handling training also focus on 

prevention of an inadvertent discharge. In case of an inadvertent discharge, workers should immediately 

follow the instructions listed in the MSDS for K-Ace.

6. END-USE EXPOSURE ASSESSMENT

K-Ace is not expected to pose significant risk to end-users when used as a flooding agent in normally 

occupied spaces. The submitter has indicated that the typical design density for K-Ace ranges from 24 to 

120 grams per cubic foot (850-4,240 g/m3

). Specifically, K-Ace is primarily designed for use in military

applications and the total amount of agent released is expected to vary from 1 to 2 gallons in a vehicle 

system (with crew compartment volumes ranging from 100 - 250 ft3

) and 30 to 70 gallons in a 9,200 ft3

(260 m3

) room system. The discharge rate of K-Ace is typically in the range of 20 g/sec to 80 g/sec, with

the extinguisher discharging entirely within 3-4 minutes.

Based on the most conservative scenario of these figures, the maximum exposure concentration of K-Ace 

that an end-user would be exposed to is approximately 96 g/ft3 (3,400 g/m3

), assuming that the entire 

extinguisher is released and suspended in air. However, this is an extremely conservative estimate. The 

airflow rate is not considered in this assessment, but the crew compartment of military vehicles are 

expected to be ventilated at an air flow rate of approximately 25 -150 ft3

/ min, which would further 

decrease the concentration of suspended K-Ace. Because of the low toxicity exhibited by K-Ace and the 

low inhalation concentrations anticipated during discharge, K-Ace is not considered to present a 

significant inhalation risk at end-use.
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Dermal and ocular exposure to K-Ace is not expected to pose a significant risk to end-users. In the event

of exposure to K-Ace, individuals are expected to follow the instructions prescribed in the proposed 

substitute’s MSDS. When individuals follow the precautionary measures described in Section 4 and 

Section 5.2, risk of exposure and irritation will be unlikely.

7. GENERAL POPULATION EXPOSURE ASSESSMENT

This section screens potential risks to the general population from exposure to releases of K-Ace to 

ambient air, surface water, and solid waste. K-Ace is not expected to cause a significant risk to human 

health in the general population when used as flooding agent in normally occupied or unoccupied spaces. 

The only consumer exposure to K-Ace will be during discharge of the extinguishers in occupied spaces. 

When the precautionary measures described in the proposed substitute’s MSDS and Section 4 and Section 

5.2 of this risk screen, no adverse health effects are expected.

7.1. Ambient Air

K-Ace is not expected to pose a risk to human health in the general population in ambient air 

concentrations. K-Ace is composed of water (50%) and potassium acetate (50%), which is commonly 

used in pharmaceuticals, foods, and textiles. Therefore, K-Ace is not expected to be a safety concern for 

ambient air contamination.

7.2. Surface Water

K-Ace is not expected to pose a significant risk to human health or the environment when proper disposal 

procedures in accordance to local, state, and federal requirements are followed. K-Ace is considered to be 

readily biodegradable and relatively harmless to aquatic life. As discussed in the Background Document, 

the physicochemical properties of the majority of halon substitutes make it unlikely that the substitutes 

would be released to surface water as a result of use. In the case of K-Ace, it is expected that all of the 

constituents would rapidly aerosolize during expulsion from the container and then settle as a salt water 

film on surfaces within the space (as opposed to becoming airborne and settling on a nearby stream). 

After settling, cleanup would involve confining the release, recovering as much of the potassium acetate 

solution as possible, then washing/rinsing of surfaces, and then disposing of the waste in accordance with 

local, state, and federal requirements. It is important to note that activation of K-Ace systems are expected 

to be infrequent (i.e., in case of a fire emergency), where the greatest risk is exposure to fire and lack of 

oxygen. EPA believes that when the disposal procedures are followed in accordance to local, state, and 

federal requirements, K-Ace does not pose a significant risk to human health or the environment during 

end-use. 

7.3. Solid Waste

K-Ace is not considered to be hazardous waste under EPA regulations implementing the Resource 

Conservation and Recovery Act. During post-activation clean-up procedures, clean-up residues should be 

disposed of in accordance with requirements appropriate for those materials, as outlined in the proposed 

substitute’s MSDS and local, state, and federal regulations. EPA believes that when these disposal 

requirements are met, K-Ace does not pose a significant risk to the general population or environment.

8. VOLATILE ORGANIC COMPOUND ASSESSMENT

Potassium acetate and water, the only constituents of K-Ace, are not considered to be volatile organic 

compounds (VOCs). Therefore, emissions of K-Ace are not considered to be a contributor to VOC 

emissions. 
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9. REFERENCES

Amerex Defense. 2012a. Response to Incomplete SNAP Submission for K-Ace in Total Flooding EndUse. May 24, 2012.

Amerex Defense. 2012a. Response to Incomplete SNAP Submission for K-Ace in Total Flooding EndUse. July 13, 2012.

Amerex Defense. 2011c. SNAP Submission to EPA for K-Ace in Total Flooding End-Use. February 8, 

2012.

EPA 1994. "Risk Screen on the Use of Substitutes for Class I Ozone-depleting Substances: Fire 

Extinguishing and Protection (Halon Substitutes)," U.S. Environmental Protection Agency, 

March 1994.

Forster, P., V. Ramaswamy, P. Artaxo, T. Berntsen, R. Betts, D.W. Fahey, J. Haywood, J. Lean, D.C. 

Lowe, G. Myhre, J. Nganga, R. Prinn, G. Raga, M. Schulz and R. Van Dorland. 2007. Changes 

in Atmospheric Constituents and in Radiative Forcing. In: Climate Change 2007:The Physical 

Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the 

Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. 

Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, 

Cambridge, United Kingdom and New York, NY, USA.

OSHA. 1994. General description and discussion of the levels of protection and protective gear. 1910.120 

App B. Last updated August 22, 1994. Available at: 

http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9767

WMO (World Meteorological Organization), 2011. Scientific Assessment of Ozone Depletion: 2010, 

Global Ozone Research and Monitoring Project—Report No. 52, 516 pp., Geneva, Switzerland, 

2011.