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Past Issues

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please e-mail ammtiac@alionscience.com.

V5N1

Feature Article: Low Pressure Cold Spray

Conductive Coating – A Case Study

TechSolution 15: A Definitive Guide to

Accelerated Testing

3rd Article: Properties and Applications of

Rhenium and Its Alloys

V5N2

Feature Article: Automating Aircraft Inspections: Time and

Cost Saving Measures for the Inspection of Large Area

Aircraft Surfaces

TechSolution 16: Selecting a Nondestructive Testing

Method, Part VII: Acoustic Emission Testing

3rd Article: New Technical Resource for Scientists

and Engineers: Handbook on Visual Testing

V5N3

Feature Article: Manufacturing Readiness

Levels

TechSolution 17: Toolkit for DoD Manufacturing Engineers

3rd Article: Joint Defense Manufacturing Technology Panel

V5N4

Feature Article: US Army Builds Degradation Resistant Bridges

TechSolution 18: Polymer Matrix Composite Manufacturing Induced Defects

3rd Article: NDE for the Process Control of PMC Fabrication

V5N1 2010

V5N2 2010

V5N3 2010

Special thanks to Stephanie Knoeller for her excellent work as the primary Editor on this issue.

In Memoriam: Sadly, David J. Brumbaugh, a long time AMMTIAC staff member and friend passed away in April. His professional

contributions were many, his knowledge expansive, and his friendship irreplaceable. He is missed by all of us here and many in the

larger DoD community.

V5N4 2010
The AMMTIAC Quarterly, Volume 6, Number 1 3 http://ammtiac.alionscience.com

INTRODUCTION

Advanced materials are foundational to the capabilities of our military platforms and national defense. For decades the development

and exploitation of materials technologies has enabled the nation’s

competitive advantage in weapon systems. From the air superiority

of the F/A-22 and the strategic capability of the B-2, to situational

awareness and networking provided by our orbiting satellites, to

advanced marine systems and innovative ground systems for today’s

soldiers – all can tie system level performance benefits to the use of

advanced materials, such as lightweight metals, polymers, ceramics,

and composites. Yet today the DoD enterprise that discovers, develops, and transitions materials for exploitation by weapons platforms

is at a crossroads.

The practices and processes for material qualification and transition that have been established by the military and industrial base

through the 20th century were developed under a very different

environment than what is expected for the future. The materials

that are being developed today and those envisioned for the future

will not be served by the historic qualification and transition

processes of past programs due to the changing defense acquisition

model. The defense materials community and associated stakeholders must work together to evolve current practices if they are to

effectively exploit new emerging material concepts for national

defense initiatives.

Recently, experts gathered to discuss and address these challenging materials transition issues. This article summarizes the

background to the changing materials transition paradigm, future

challenges, stressors on current practices, recommendations for

going forward, and some best industry practices.

CURRENT ACQUISITION ENVIRONMENT

The material transition paradigm that has been used in prior

decades with multiple platform development programs and numerous insertion opportunities is not feasible in the current acquisition

environment. The current environment has a relatively low number

of platform acquisition programs and provides limited opportunities to gain fielded experience with new materials. Furthermore, the

time it currently takes to field most defense systems is quite long

and stifles transition. The current DoD acquisition process is on the

order of a decade, which risks technology obsolescence by the time

the system is fielded.

Defense acquisition programs are increasingly trending toward

concurrent development and production, a strategy that involves

significant risk. One risk mitigation approach is to use materials that

have been utilized on previous platforms to reduce cost and schedule.

If this is indeed a trend in the management of risk in weapon system

acquisition, it may be expected that future DoD major acquisition

programs will favor previously used materials resulting in limited

opportunities to transition new materials. A limited ability to transition new materials to new weapon systems will impact not only future

defense capabilities, but will ultimately have detrimental effects on

materials research, development, and workforce education. Moreover,

Tia H. Benson-Tolle

Gregory A. Schoeppner

Air Force Research Laboratory

Wright-Patterson Air Force Base, OH

The Persh Conference construct was developed as a new discussion forum for in-depth investigation and discussion to

address issues of common interest and relevance to the DoD materials and process community. It was initiated by the

Defense Science and Technology Reliance 21 Materials and Processes Panel in recognition that direct communication

between the diverse stakeholders in defense materials through a constructed format can provide rapid assessments of

evolving issues that this community faces that does not exist in traditional forums. To encourage open and rapid

exchange on the diverse and timely ideas and stimulate a broader discussion on key issues, strategic investment, and

policy options, Persh Conferences are by invitation only with no published proceedings. Diverse stakeholders are

brought together around a single topic, with perspectives ranging from technology to policy and from research to application. The format of the conferences is very interactive and is composed of talks to provide context and interactive

panel discussions to explore and probe issues and opportunities. The results of each Persh Conference are analyzed, and

assessments and recommendations developed and submitted to the DoD and shared with the participants. The forum

is unique in that it provides a holistic look at a topical subject in a national security context and enables identification

of where the materials and processes community should focus its efforts and energy in research and otherwise.

The Defense Science and Technology Reliance 21 Community of Interest provides materials technologies, processes and related research and technology products as well as the scientific and engineering expertise needed to maintain

and enhance US defense capability. Its goals are to strengthen science and technology planning by improving integration of investments with a DoD-wide strategic view and enhancing coordination between the science and technology

communities within DoD.

Persh

Conference
The AMMTIAC Quarterly, Volume 6, Number 1 4 http://ammtiac.alionscience.com

it could potentially cause the advancement of certain classes of materials to become stagnant.

CHALLENGES THAT IMPEDE MATERIALS TRANSITION

Several challenges may prevent the exploitation of high performance

materials to create weapon capabilities across various platforms.

There is a large body of anecdotal evidence and consensus within

the materials research and development communities that demonstrates how the current methods of transitioning materials are less

than desirable. Convening experts from various stakeholders

through the Reliance 21 meetings and the Persh Conference (see

sidebar) has led to the identification of many of the barriers to materials transition. Some of these challenges are discussed in the following paragraphs.

Scaling of Materials

One challenge occurs when scale-up effects from simple material

property testing coupons to larger panels or components are not

well understood. For example, early material performance of an

advanced metallic alloy for a particular application was measured

from simple coupon samples. These tests showed that the material

met all of the targeted requirements for the application, which

resulted in additional testing and investment in the material. Once

the material processing and manufacturing were scaled up to larger

panels, testing of the larger panels revealed that the material no

longer met the performance requirements. Failure of the material to

meet requirements at the larger scale was due to residual stresses that

were insignificant and went largely unnoticed in the initial coupon

specimens but were significant in the larger panels. A common reason for material transition failure is not necessarily insufficient

coupon data, but failure to properly account for scale-up in the

manufacturing processes.

Point Design

Materials qualification for cross-platform use typically focuses on a

single type of application. For instance, the suitability of a material

for use in airframe structures is tested in a limited range of environments and has different qualification tests than for an aircraft engine

application. Under past and current practices the average number of

qualification tests for a single application range from 1000 to 3000

specimens and requires from 1 to 3 years for completion. To qualify

a material for multiple types of applications becomes increasingly

difficult and costly. The research and development community does

not typically have the resources to mature technology to the point

that the material can be qualified and transitioned to a program.

A result of the push for more rapid transition has been the strategy to qualify materials to a point design – that is, the testing is limited to only address a specific component design, set of loads, and

environment. This practice reduces the time and cost of inserting a

material. However, materials qualified to a point design are not

readily translatable to other applications because the reduced testing

eliminates the possibility of direct transition to other applications.

Weapon System Life and Materials Availability

The requirements creep seen over a weapon system’s life represents

a challenge to materials qualification and is unique to the defense

community. Many weapon systems have service lives spanning several decades that can include multiple service life extension efforts.

After a material is successfully transitioned to a major platform, long

service lives often necessitate repair or removal and replacement of

aging or damaged materials and components. Material obsolescence

that may involve changes to constituents, environmental law

changes necessitating a change to the material or how it is processed

and second source qualifications are among the reasons for materials to undergo costly re-qualification numerous times throughout

the life of the platform.

Alignment of Material Developer and Material Integrator

Requirements

The alignment of the material maturation timeline with the material

selection phase of the acquisition timeline is a major factor in successful material transition. Case studies have shown that materials can be

successfully qualified when the material developer has early visibility

into well defined material requirements and needs, the product is well

developed for the application, and the material development and

qualification are fully resourced with a strong customer pull. Material

development and qualification are slow or unsuccessful when the

requirements are poorly articulated, thereis a late definition or change

in requirements, or there is a lack of a clear value proposition. Late or

poor definition requirements can lead to incapable material for the

application that can significantly slow or impede qualification and

ultimately jeopardize program execution.The current lack of synchronization between material development and application opportunities

may become a greater challenge as DoD weapon development cycles

adapt to the current highly-dynamic threat space and finds needs for

diverse, tailored and low production-number weapons. The material

supplier must have a clear understanding of the customer’s qualification testing requirements that may be application specific and different for each customer. Finally, qualification efforts can be hampered

by second-source qualification efforts as well as changes in requirements, in needs or in schedule.

Risk Reduction Methods

Current empirical qualification approaches are widely seen as costly

and time consuming, and some consider them antiquated processes

that penalizes materials insertion. Although improvements to the

qualification process are seen as long overdue and much needed, it

is the responsibility of the certification community to manage risk,

and any alternative approaches to statistically-based materials databases will be required to be risk neutral.

Five factors (prerequisites) responsible for reducing the risk for

transition (see sidebar) have been identified for successful application of advanced structural material systems (see Figure 1). The

prerequisites for successful transition are: stabilized materials and

Figure 1. Factors in Past Successful Structural Materials Transition

Structural

Integrity Allowables

Evaluation of produvibility

Material

development

Process development

Process scale-up

Accept/

reject

criteria

Material screening

Manufacturing methods development

Facility assess- ment

• Element • Subcomponent • Analysis • Structural testing

• Repairability • Maintainability • Reliability

I. Stabilized

Materials

and

Processes

V. Supportability IV. Predictability of

Structural Performance

II. Producibility: Manufacturing Scale-Up

Cannot just focus here; have to look at the entire picture

Five Factors for Technology Transition

III. Characterized

Mechanical

Properties

(start of EMD)
The AMMTIAC Quarterly, Volume 6, Number 1 5 http://ammtiac.alionscience.com

processes, demonstrated producibility and mature supply chain,

characterized mechanical properties, predictability of structural performance, and demonstrated supportability including repairability.

These factors, as desirable as they are, may not be achievable for

future materials applications due to cost or time constraints in the

same manner as they have been in the past.

When system and platform manufacturers are in competition for

major defense acquisition programs, they are willing to consider the

insertion of higher risk technologies for competitive performance

and cost advantages. However, after program award, manufacturers

typically become more risk averse and technologies used in the

Technology Development phase that have not sufficiently matured

or are determined to be too high risk may not make it into the

Engineering & Manufacturing Develop phase of the program.

Knowledge and Experience Base

There is a strong sense that the community needs to better capture

the materials development, qualification and transition experience of

all stakeholders, down to the experiences of individual people.

Today’s practice of transferring experience and knowledge often relies on

non-formal collegial or mentor-toapprentice relationships that may be

ad hoc and non-archival in nature.

Today there exists no formal national

focus on providing education in critical topics such as materials design (versus a materials selection process) and

in computational tool integration

across disciplines. Such training would

provide for a more robust knowledge

transfer. Anecdotal evidence suggests

that several elements are critical for successful transition of materials:

people and their education, transfer of knowledge, trust and comfort

with new materials and processes, and the ability to communicate.

Computational Tools

A common theme identified by researchers, material suppliers, systems

integrators, and acquisition and warfighter stakeholders is the need to

shorten the time for the materials development cycle without increasing the risk associated with inserting a new material. Material testing

has been identified as one aspect of the materials development cycle

that can potentially reduce development time and cost. However, there

is recognition that the certification community has historically managed risk in part through the empirical, statistically-based material

allowables process. Therefore, processes to reduce testing requirements

that employ critical strategic testing with predictive models must be

developed, matured and validated to provide a level of confidence at

least as good as the existing empirically-based processes. Currently, the

lack of high fidelity and high confidence predictive models is a significant barrier to implementing these processes.

Stakeholders have identified the growing need to bring

enhanced computational capabilities into the materials development cycle. Utilization of computational methods is sought not

only to guide and reduce the material testing needed to fully characterize material performance, but also to help guide the design of

new materials. Additionally, material suppliers can potentially use

matured computational tools for initial material screening and the

development of a business case early in the material development

cycle for a given material’s application. Articulation of the return

on investment (ROI) or business case for using a material is critical for material trade studies in the early phase of DoD acquisition

programs. Some of the current challenges hampering the expanded

use of computational tools are computer code run times, lack of

integration of various tools and codes, and the fact that the use of

commercial codes typically requires specialized expertise and training. Microstructure models and

process modeling require specialized

knowledge. Challenges hampering

expanded use of computational tools

in materials development and transition also reside in current curricula, which do not yet broadly

emphasize computational tools in

materials science and engineering.

EMERGING TRENDS AND BEST

PRACTICES

Some successful practices in facilitating the transition of new materials from many perspectives ranging

from material suppliers to systems integrators have been collected

and articulated by those with recent experience in the process. Many

factors have been identified across stakeholders as critical to rapid

qualification. These include communication amongst all stakeholders, early visibility into system requirements for the material supplier, well developed testing protocols, understanding of design drivers

by all parties, and OEM teaming with material developers and

suppliers. Early involvement of the acquisition program office is

essential as risk management, not technology insertion, is paramount to a major acquisition program. A material’s capabilities

must link to requirements and it has been shown that technology

pull has been more effective than technology push in getting new

materials onto DoD platforms. Identification of the application first

to guide material development is often more successful than trying

Figure 2. Technology Transition – Managing Risk, Payoff,

and Timing

When deciding what technologies to insert into weapon systems and platforms, technology integrators must weigh

the interdependence of timing (technology maturity level), payoff (ROI), and risk. For today’s DoD acquisition

programs, most new materials must be considered in the Materiel Solution Design Phase prior to Milestone A or

they are viewed as being too late to impact a program. However introducing a new material into a program before

it is at an acceptable technology readiness level (TRL) and manufacturing readiness level (MRL) makes it difficult

to assess the business case and ROI making it high risk. New materials are viewed as having lower ROIs than is initially projected early on in their development phase because selection decisions must be made early when quality

information is limited. Less mature technology is higher risk to the program and is not likely to be on a critical

program path unless there is a compelling high payoff in performance or ROI. There is a potential for accepting

higher risk for enabling revolutionary materials, but there is risk aversion to new evolutionary materials that are low

payoff in terms of cost and performance. Figure 2 summarizes some of the interactions of timing, payoff and risk.

Risk as a Factor

in Transition

• Early involvement of acquisition program essential

• Small program window for transition opportunity

• Need acceptable TRL

& MRL at need date

• Less mature technology is higher risk, not

likely to be on critical

program path

• Potential acceptance

of higher risk with

high payoff revolutionary technologies

• Risk aversion to low

payoff evolutionary

technologies

Timing Payoff

Risk

Early Requirements Definition

Technology Maturation

Performance/Cost ROI
to find a home for a newly developed material.

Collaborative relationships between material suppliers and the

integrators have been a key to addressing causes for the slow adoption of new materials. Some successful practices include establishing

a roadmap working group to coordinate materials development and

structures development roadmaps. These provide early visibility into

requirements and early identification of technology need dates for

planning the material and supply chain maturation. Such a relationship serves to develop a collaborative testing approach for standard

methods and minimizes testing issues. When materials suppliers

have a clear understanding of the customer’s material and testing

requirements, there is a greater chance that the material will ultimately meet the customer’s needs. Beyond specific platform material development, the integrator must inform the material supplier

community of future material needs well in advance to ensure that

the supply base is actively working on technologies to meet the

needs of the next-generation platforms.

The aforementioned best practices have been used over the past

decade within the DoD materials community. However, in light of

the changing nature of the DD landscape and its loss of stature as

being the nation’s driver for material technology, innovation may be

found by working with non-traditional, forward leaning companies

for materials development and transition. Best practices from other

sectors and markets such as automotive and pharmaceuticals on

approaches for technology transition may offer useful insights into

processes that can be exploited to improve DoD technology transition. New materials such as nanocomposites are being successfully

transitioned into some markets, and emerging materials such as

active materials are being developed and considered within several

industries. Several factors that enhance successful implementation

across these other market sectors have been identified. These included close communication between all parties involved in product

development, the use of processes for prioritizations and review of

progress, and recognition of the role of identifying and nurturing

new technologies to remain competitive. Within for-profit companies, it is critically important to transition new technology into marketable products to retain a competitive advantage.

Innovative processes and methodical approaches are often used in

industry to focus research, and quickly mature promising research. Yet

it is acknowledged that such approaches can both enable and hinder

materials development and transition. Business managers value these

approaches sincethey allow for the assignment of a valueto R&D and

the tracking of R&D, but some assert that innovation suffers under

such systems. In some cases, research is only funded if it can be identified how the technology will be utilized in a product. Some factors

that influence the business case include the timing of the technology

investment, the development and insertion cost, the availability and

quality of the material, and the supplier’s knowledge of the integrator’s needs. Definition and articulation of the business case for the

development of new materials is important and in some cases there is

a reluctance to be first to use a technology knowing that once a precedent has been established to use the technology, it is easier to integrate

into a product. Some companies choose to rely upon external collaborations for basic research rather than performing it themselves.

Research and development are more likely to be successful if multidisciplinary product teams are established early in the design cycle to

guide product development. Today many are increasingly recognizing

the importance of learning from other market activities, research, and

needs. In addition, there is a growing awareness of the necessity to

leverage across communities, recognizing that innovation comes from

multiple sources, and not just from internal resources. A cultural shift

away from the mentality of ‘not invented here’ and a reliance on leverage appear to be emerging and increasingly valued.

A PATH FORWARD

Several recommendations for improving material transition resulted

from the Persh conference. These are explained in the following

paragraphs.

It is recommended that the Defense Science Board and other

appropriate organizations are engaged to study various approaches

to qualifying materials for diverse markets and recommend an alternative method for the DoD of the future. Specifically, various

industries should be assessed to identify best practices. Previous

material qualification processes should be built upon and updated

based on current geo-political, economic, defense, and technology

factors. The need and role of government supported initiatives

should be addressed to facilitate a seamless technology transformation from inception to implementation. For instance, these could

include initiatives that promote more integrated collaboration

between systems manufactures and material suppliers (e.g., to

demonstrate breakthrough improvements as a result of having suppliers fully engaged from the onset), or initiatives that are open to

new innovations, including rule and process changes to exploit

advanced concepts to the fullest extent. Finally, the Defense Science

Board or Institute for Defense Analysis should be engaged to perform a study and recommend the optimum role of government

S&T in shaping future qualification/certification processes.

Another recommendation is to establish an OSD 6.3 Program

Element that addresses scale up and transition of materials technology.The appropriate funding level would need to be determined. OSD

should also be chartered to perform an industrial base assessment to

determine how to best posture industry to rapidly exploit and transition new materials and processes for improved weapons capabilities.

Recommendations of how to better incorporate materials knowledge, including modeling, into the education system should be

developed by bringing together various entities, such as the National

Materials and Manufacturing Board (NMMB) of the National

Academies; government science, technology, engineering, and math

(STEM) education groups; and a round table of material-centric

technical societies (such as MRS, SAMPE, and ASM). This should

focus on future-leaning needs such as the incorporation of probabilistic concepts, computational methods, and materials design (as

opposed to materials selection). Furthermore, the DoD should evaluate forums that can be used to actively integrate all stakeholders for

more efficient communication and to build on best practices.

Finally, a DoD-centric computational materials study should be

performed with an objective look at roles and payoffs of computational materials science and engineering (CMSE) and integrated

computational materials engineering (ICME) in the development

and transition of materials in today’s geo-political and economic

landscape for defense applications. Several general CMSE studies

have been performed in the past, and therefore this should benchmark tools circa 2011 and look to define capabilities that can

impact materials transition today as well as foundational research

required for envisioned future needs.

The AMMTIAC Quarterly, Volume 6, Number 1 6 http://ammtiac.alionscience.com

To comment on this article, email: ammtiac@alionscience.com
techsolutions 19

Blast Resistant Fenestration Design & Testing

The AMMTIAC Quarterly, Volume 6, Number 1 7 http://ammtiac.alionscience.com

INTRODUCTION

Blast resistance remains a top priority for high-risk government,

defense, and financial buildings. Windows, doors, and skylights

are, in most instances, the points of vulnerability when considering

a structure’s ability to withstand explosive forces and protect its

occupants. It is critical that these components be designed to the

appropriate standard and thoroughly tested to validate their infield performance. In fact, many government agencies, private

building owners, consultants, and engineering firms mandate that

their building components be tested and subsequently rated based

upon their ability to mitigate the effects of blast events as well as

threats from ballistic and forced entry attack. This article summarizes the characteristics and effects of blast waves, and discusses the

hardware, software, and methodology that allows their simulation

within a test environment.

BACKGROUND

During any blast-type event, building occupants can be injured or

killed by: direct exposure to blast loadings (pressure or shock waves),

the impact of fragments and debris, impact with surroundings when

either a structural element or the person is impelled by the blast

wave, or structural collapse.

Of these, limiting the impact of debris is particularly important

in the case of fenestration (windows, doors, and skylights).

Statistics show that approximately 80 percent of the injuries resulting from blast events are caused by airborne shards of glass from

broken windows. These glass shards can fly inward at speeds greater

than 200 feet per second (136 mph).

Blast Characteristics

When an explosion occurs, there is a near instantaneous heating and

subsequent expansion of the surrounding air, which results in the

formation of a shock wave. The shock wave travels away from the

source in a radial fashion at supersonic speeds, while also decreasing

rapidly in magnitude. This decrease in magnitude is modeled using

the inverse cube of the distance from the explosion site.

The archetypal blast waveform features a positive phase that is

characterized by a virtually instantaneous rise to the peak overpressure and rapid exponential decay until it reaches a value of zero. At

this point, air backfills the vacuum that is created as the blast wave

passes. This is termed the negative pressure phase.

The peak pressure of the blast, which is dependent on the charge

weight, and thetime over which theinitial pressure wave decays to zero

together define the impulse energy delivered. While peak pressure is

applied instantaneously, the delivered energy or impulse is cumulative.

For most architectural design purposes, the blast impulse or

blast loading waveform may be simplified and assumed to be of a

triangular shape with the peak overpressure decaying linearly to

ambient pressure in a time known as the positive phase duration.

In this case, the impulse is simply the area of a triangle as shown in

Figure 1. The impulse is calculated using Equation 1, where I is the

impulse in (psi-ms), P is the peak pressure (psi), and td is the duration time in (ms).

I = (1⁄2) td • P Equation 1

A more precise characterization may be obtained using a software

package that implements the standard Kingery-Bulmash air blast

equations used in most Department of Defense (DoD) technical

manuals. Alternatively, tables of pre-determined shock parameters

may be used to estimate blast pressure and impulse.

When a shock wave encounters a structure, it may be reflected.

The reflection causes a pressure load on the structure that also has

a peak pressure and impulse. In general, the reflection is a function

of the angle of incidence. For the portions of the structure that are

perpendicular to the shock wave propagation (zero angle of incidence), the reflected pressure is maximum and greater than that

of the original shock wave. For portions of the structure that are

parallel to the shock wave propagation (90° angle of incidence),

the reflected pressure is approximately equal to the free field pressure of the explosion. As the shock wave traverses, highly damped

pressure oscillations occur as the pressure returns to its ambient

value. This results in a negative phase pressure in both the free field

and reflected pressures. It is the reflected pressure and impulse that

the designer must consider when evaluating a structure or its

fenestration. Figure 2 illustrates the interaction between a shock

wave and a building.

Since a shock wave is characterized by both magnitude and time, it

is a dynamic load. Accordingly, the fenestration element will have a

dynamic response which is dependent on both the strength and stiffness of the product. Common fenestration materials have different

physical and mechanical properties; thus, their dynamic response can

be substantially different between two shock waves of identical peak

Typical Blast Wave

Incident (Side-on) Overpressure

Peak Overpressure (P) Measured in psi

Impulse (I ) Measured in psi•ms

Positive Phase Duration (t

d)

Negative Phase Duration

Ambient Atmospheric Pressure

(- psi)

Time (ms)

Pressure (psi)

(+ psi)

Figure 1. Blast wave diagram (courtesy of American

Architectural Manufacturers Association (AAMA))

Joseph A. Reed

Brady McNaughton

Architectural Testing, Inc.

York, PA
The AMMTIAC Quarterly, Volume 6, Number 1 8 http://ammtiac.alionscience.com

AMMTIAC techsolutions 19 A D V A N C E D M A T E R I A L S , M A N U F A C T U R I N G A N D T E S T I N G

pressure, but different impulses. If the period of the shock wave is

closely matched to the natural period of the component, there may be

an amplification of the component response analogous to resonance.

Therefore, it is important to evaluate the product at precisely the specified shock wave conditions and for the exact construction intended

for the project.

DESIGNING BLAST RESISTANT FENESTRATION

To mitigate the hazards posed by flying glass fragments, window

system designs should be balanced, meaning that the glazing*,

frames, and anchorage are able to survive a blast loading. In general,

if one part of the system fails, the entire system will fail. Similarly, if

the system has a higher capacity than the supporting wall, when the

wall fails the entire window system may be blown into the facility.

The basic criteria for the design of blast-resistant or blast mitigating fenestration systems are that the glass should remain intact and

in the frame, broken but not blown out; the frame must stay

attached to the wall; and the wall must remain intact to hold the

frame. Protective glazing measures would also be appropriate for

buildings that are located near high risk targets, even though the

buildings themselves are not considered a target.

To predict the behavior of glass under a blast load damage

models should be developed for windows, and the glazing hazard

levels determined. These models can be used to predict the outcome of various blast loads. Engineers prepare these models using

software such as WinGard†, Winlac‡, and HazL§, developed by

US Government agencies. The developed damage models are in the

form of resistance-deflection functions, describing how glass

deflects and breaks under pressure and how the glass shards are

projected once released from the windows. Pressure-impulse (P-I)

diagrams, derived from the resistance-deflection functions, help to

rapidly analyze windows under a range of loads.

Once the damage functions are set, the applied blast load for each

window is plotted on the P-I diagram and the resulting damage level

is recorded. A graphic of the damage levels for existing windows

helps to visualize the high hazard areas, and the potential for personnel injury. Such analyses, however, are typically done on a component basis only and to different design methodologies. That is, the

glazing is analyzed for fragmentation potential with simplified

theoretical boundary conditions; frame members are analyzed for

deflection and stress without considering the structural integrity of

the glazing; and connections and anchors are analyzed for ultimate

strength. Estimating a total system response by aggregating these

individual analyses often results in a very conservative design.

Physical testing of the complete assembly to the actual design loads

provides a more realistic validation of the assembly.

Performance Standards

To ensure that components are manufactured and buildings are

designed to meet the challenges of blast resistance, standards have

been developed. The two most widely used glazing performance

standards and hazard-classification schemes are published by the

General Services Administration (GSA) and the DoD.

General Services Administration

The GSA first published its Security Criteria, which includes criteria for mitigating risk from window glass fragments, in 1997. The

Interagency Security Committee (ISC) later adapted these criteria

for at-risk facilities of all federal agencies, except those under DoD

jurisdiction. The GSA also developed GSA-TS01-2003, Standard

Test Method for Glazing and Glazing Systems Subject to Dynamic

Overpressure Loadings to provide guidelines for testing using actual

explosive charges or simulated blasts.

The GSA documents define five performance conditions that

indicate whether and how far glass shards penetrate into a room

when the window and wall segment are subjected to a blast of specified peak pressure and impulse. The performance conditions are

numerically defined on a scale from 1 (“safe” – the glass does not

break and there is no visible damage to the glazing or frame) through

5 (“low” – the glass fails catastrophically, projecting fragments more

than 10 feet from the window to impact a vertical surface [wall or

test “witness panel”] more than two feet above the floor).

Department of Defense

In parallel with the GSA/ISC efforts, the DoD has developed standards of its own known as Unified Facilities Criteria (UFC). The

most applicable is UFC 4-010-01, entitled Minimum Antiterrorism

Standards for Buildings. More stringent than those required by the

GSA/ISC Security Criteria, this criteria defines its own levels of

protection or hazard ratings and, in the architectural category,

includes minimum requirements for windows, skylights, and doors

in new and retrofitted buildings.

UFC 4-010-01 defines five Levels of Protection based on likelihood and degree of building collapse and personnel injury due to

flying glass fragments. These levels of protection are established

once the standoff distance is determined and are similar to, but

described differently from the performance conditions and protection levels cited in the GSA standard. The levels of protection are

summarized in Table 2.1, page 2-7 of UFC 4-010-01.

To minimize the hazards caused by flying glass fragments, UFC 4-

010-01 prescribes specific provisions for new and replacement glazing

and window frames, noting that “window and door designs must treat

glazing, frames, connections, and the structural components to which

they are attached as an integrated system.”

PERFORMANCE CERTIFICATION AND TESTING

UFC 4-010-01 states that it is acceptable to dynamically test window

and skylight systems to determine their performance as equivalent to

or better than their applicable hazard rating. This may be done as an

alternative to the prescriptive provisions of the standard. Such testing

includes the entire window or skylight system and connections, and

is conducted in accordance with ASTM F 1642 -04, Standard Test

Figure 2. Shock wave interaction with a building.

P

INITIAL

EVENT

FREE-FIELD

DECAY

REFLECTED

PRESSURE, Pr

NEGATIVE PHASE

Pr

I = (1/2)Pr•t

d

t

d

t

o

Po
The AMMTIAC Quarterly, Volume 6, Number 1 9 http://ammtiac.alionscience.com

AMMTIAC techsolutions 19 A D V A N C E D M A T E R I A L S , M A N U F A C T U R I N G A N D T E S T I N G

Method for Glazing and Window Systems Subject to Airblast Loadings.

Testing reveals problems such as inadequate fasteners, excessive

frame deflection, or brittle failure. Testing and the subsequent

analysis is a useful tool for designers, architects, consultants, and

manufacturers since it aids in the development of improved products that better mitigate the glass fragmentation hazards.

To conduct the tests necessary to qualify a fenestration system, a

fully glazed and assembled mock-up must be prepared using

approved shop drawings. Since the method of installation for a

blast mitigating product is as important as the product itself, it

must also be evaluated during the testing. Therefore, the mock-up

must accurately represent the project in every detail, including

glazing, hardware, operation, installation and the type, number,

arrangement, and orientation of the anchoring fasteners. Tests may

be conducted in an open air arena with live explosives or using a

shock tube.

Arena Test

The arena test is an open-air test in which a test subject is installed

in a support structure and exposed to an actual explosion. For arena

tests, the characteristics of the blast wave (peak pressure and

impulse) are determined from handbooks or with computer software. These characteristics are then used to select an appropriate

explosive weight based upon the available standoff distance (SOD)

at the arena test facility. Figure 3 shows an example test set-up. The

advantages and disadvantages of the arena test are summarized in

Table 1.

Shock Tube Test

The shock tube test uses a pressure vessel charged by air or nitrogen

to test a sample. The key components are illustrated in Figure 4.

The driver is a pressure vessel with an adjustable volume that is

closed by membranes in the initiator flange. When the membranes

burst, the rapid release of pressure creates a shock wave that is tuned

by the expansion duct, cone, and shells to replicate the reflected

pressure profile generated by the specimen.

For a particular charge weight and standoff, the characteristics of

the blast wave (peak pressure and impulse) are determined from

the same handbooks or computer software used in arena testing.

The test engineer uses the parameters to set the shock tube driver

volume, driver pressure, and shell configurations such that they

replicate the blast wave. Shock tube configurations for various peak

pressures and impulses are established by developing performance

curves when the shock tube is commissioned. The advantages and

disadvantages of the shock tube test are presented in Table 2.

Some shock tubes have data capture capabilities that include

high-speed, high-resolution color digital video up to 5,000 frames

per second and data collection rates up to 10,000,000 samples per

channel per second. If equipped with a reusable test frame, fast test

set-up and repeat testing are enabled. In addition, tests can be rerun with varied parameters simply “dialed in,” allowing repeated

testing of specimens in rapid succession, typically ten tests per day,

under a spectrum of conditions. Thus, shock tubes are well suited

for balanced design validation by progressively increasing load on

one window to establish glass break before frame failure.

Once the tests are completed, post-blast engineering analysis of

blast parameters and shatter patterns determines the level of blast

protection rating provided by a product.

Figure 3. Arena test set-up. Diagram courtesy of American

Architectural Manufacturers Association.

Figure 4. The key elements of a shock tube.

Table 1. Arena test advantages and disadvantages.

Advantages Disadvantages

• Most accurately reproduces the blast waveform • High cost

• Several products can be tested simultaneously • Area required must be quite large with long standoff distances, and be isolated from the public

• Few specimen size limitations • Requires multiple test chambers (witness rooms) and instrumentation if multiple tests are

conducted with one blast

• Long set-up time for initial and repeat test runs

• Subject to weather variations

SOD 50 ft (15 m)

SOD 100 ft (30 m)

Driver

Expansion Duct

Shells Witness Chamber

Specimen Frame Initiator Flange Cone
The AMMTIAC Quarterly, Volume 6, Number 1 10 http://ammtiac.alionscience.com

AMMTIAC techsolutions 19 A D V A N C E D M A T E R I A L S , M A N U F A C T U R I N G A N D T E S T I N G

BLAST CERTIFICATION

Once the test results and analyses are completed, blast-resistant fenestration products may be third-party certified by programs that

include laboratory testing, validation of the manufacturer’s quality

assurance program, and plant inspections.

Certification can take either a “product-specific" path by testing at an ISO 17025-accredited laboratory according to UFC,

GSA or other accepted performance standards, or a “project specific" path by testing to confirm compliance with individual

project specifications and approved shop drawings. Either path

requires continued, demonstrated compliance with ICC-ES AC10

quality control documentation requirements at the manufacturing

plant and verification. Each certified product and actual installation must comply with the referenced standards, as confirmed

during periodic on-site audits of manufacturing plants and installation sites.

CONCLUSION

While comprehensive protection against the range of possible

threats may be cost prohibitive, an appropriate level of protection

intended to lessen the risk of mass casualties resulting from blasttype events can be provided for all personnel at a reasonable cost.

Testing and rating of the ability of blast-resistant fenestration products to meet current standards, while not a guarantee of absolute safety, is the best way to maximize protection while optimizing building

enclosure design to meet all building and site functional requirements. In general, the lower cost and fast turnaround of shock tube

testing is likely to result in more products being tested and verified

for blast-resistant performance than if arena testing alone is used.

NOTES * Window glazing is the glass portion of the window assembly.

† Window Glazing Analysis Response Design. This software was the first available for

the prediction of glass hazards and has become a national standard used by many

agencies. A state-of-the-art method to analyze and predict the behavior of window

glass under blast loads, this program calculates and graphically displays the response

of window systems subjected to blast loads. WinGARD is available for download at

www.oca.gsa.gov.

‡ Window Lite Analysis Code. Versions 4.0 and later are derivative versions of the

WinGARD GSA code adapted to meet the unique requirements of the US

Department of State.

§ Window Fragment Hazard Level Analysis. This program calculates the glazing

response to a blast loading and provides a debris transport model for predicting fragment trajectory. It allows modeling of monolithic glass or plastic windows, laminated windows, insulated glass units and windows retrofitted with anti-shatter film.

HazL is available for download from https://pdc.usace.army.mil/software/hazl/.

GENERAL REFERENCES

Standards and Test Methods

United States General Services Administration, “Standard Test Method for Glazing

and Glazing Systems Subject to Dynamic Overpressure Loadings,” GSA TS01-2003,

1 January 2003, http://www.gsa.gov/graphics/pbs/Standards_GSATestingStandard.

pdf, accessed 20 January 2011.

United States Department of Defense, “Unified Facilities Criteria (UFC): DoD

Minimum Antiterrorism Standards for Buildings,” UFC 4-010-01, January 22,

2007, http://www.protectiveglazing.org/resources/UFC4-0100122%20Jan%20

2007.pdf, accessed 20 January 2011.

United States Department of Defense, “Unified Facilities Criteria (UFC): DoD

Minimum Antiterrorism Standoff Distances for Buildings (FOUO),” UFC 4-010-

02, 19 January 2007.

Headquarters, Department of the Army, “Physical Security,” Field Manual FM 3-

19.30, 8 January 2001.

United States Department of Defense, “Unified Facilities Criteria (UFC): General

Building Requirements,” UFC 1-200-01, 16 August 2010.

American Architectural Manufacturers Association, “Voluntary Guide Specification

for Blast Hazard Mitigation for Fenestration Systems,” AAMA 510-06, 2006.

ASTM International, “Standard Practice for Determining Load Resistance of Glass

in Buildings,” ASTM E1300-04e1.

ASTM International, “Standard Test Method for Glazing and Glazing Systems

Subject to Airblast Loadings,” ASTM F1642-04, 2010.

ASTM International, “Standard Practice for Specifying an Equivalent 3-Second

Duration Design Loading for Blast Resistant Glazing Fabricated with Laminated

Glass,” ASTM F2248-03.

International Council Code – Evaluation Service, “Acceptance Criteria for Quality

Documentation,” ICC ES-AC10, www.icc-es.org.

International Organization for Standardization, “Glass in Building – ExplosionResistant Security Glazing – Test and Classification for Arena Air-Blast Loading,”

ISO 16933, 2007.

International Organization for Standardization, “Glass in Building – ExplosionResistant Security Glazing – Test and Classification by Shock-Tube Loading,”

ISO16934, 2007.

Published Articles

Remennikov, A.M., “A Review of Methods for Predicting Bomb Blast Effects on

Buildings,” 2003, http://ro.uow.edu.au/cgi/viewcontent.cgi?article=1360&context=

engpapers, accessed 21 January 2011.

Swisdak, M.M., Jr., “Simplified Kingery Airblast Calculations,” Indian Head

Division/Naval Surface Warfare Center, August 1994, http://www.dtic.mil/

cgi-bin/GetTRDoc?AD=ADA526744&Location=U2&doc=GetTRDoc.pdf,

accessed January 21, 2011.

Table 2. Shock tube test advantages and disadvantages.

Advantages Disadvantages

• Lower cost when compared to the • Limitations on peak pressure

arena test

• Indoor environment permits control • Limitations on specimen size

and reproducibility of test conditions

• No weather delays

• Rapid “test-adjust-retest” capability

assists design efforts

• Unique test parameters can be

easily dialed in

Joseph A. Reed, PE, is Director for Engineering and Product Testing at ATI. Mr. Reed holds a Master of Science in Civil Engineering from Lehigh University

and is the inventor or co-inventor on 14 international patents. He has active engineering experience since 1988 and joined Architectural Testing, Inc. in 2002,

where he is now responsible for structural analysis of building envelope components and cladding constructions relating to building code compliance and project requirements. He guides the preparation of test routines and analyzes results for wind and blast load performance of window, storefront and curtainwall installations designs and conducts structural analysis of fenestration assemblies and components.

Brady W. McNaughton, P.E., Manager of the Security Research Center, has been involved in security related testing and engineering since he joined the

Architectural Testing team in 2006. He oversees all blast, ballistic resistance, forced entry resistance and fire testing performed in the Security Research Center.

Brady is a member of several professional organizations and currently has Professional Engineering licenses in two states.
The AMMTIAC Quarterly, Volume 6, Number 1 11 http://ammtiac.alionscience.com

INTRODUCTION

Halon fire extinguishants are clean, meaning that they can suppress

fires without causing additional damage as a result of their use.

Although halon is an excellent extinguishant its production has

been banned for most applications due to its contributions to ozone

depletion. For decades, researchers have been working to develop an

equally well performing replacement with limited success. This

paper reviews the development of halon, its characteristics, the alternatives that have been developed, and the reasons that these alternatives are inadequate.

HISTORICAL BACKGROUND

The history of fire extinguishants goes back in antiquity to at

least the time when a caveman lost control of a bonfire while

roasting his most recent hunting success. Water was likely the

first extinguishant. It worked well and no one was particularly

concerned about the mess created in dousing the fire. Water continued as the principle

extinguishant into modern times, being used

extensively in well known

historical events such as

the Great Chicago Fire of

1871. The focus was

placed on putting out the

fire as quickly as possible

to save lives; extinguishant damage was accepted as a necessary evil.

Water and dry chemical based systems (e.g., bicarbonates) have

continued to evolve into highly engineered and effective 21st century options, but still can create significant damage in the course of

application. In addition to facility or equipment replacement costs,

downtime and critical continuity-of-use considerations often have

very high value, especially in modern DoD systems.

HALON DEVELOPMENT

Through the early and mid-20th century, questions were raised as

to whether it was possible to suppress fires without creating

immense damage during the extinguishing process. Extinguishing

agents such as carbon tetrachloride (CCl4), bromomethane

(CH3Br), and bromochloromethane (CH2BrCl) were developed

in the early 1900s and found to provide the desired clean extinguishment characteristics. Although widely employed in military

and civilian applications during this period, these agents were

found to be highly toxic.

As expensive, complex, and mission critical electrical devices

entered military service, especially during WWII, the need for an

extinguishing agent that was both clean and of low toxicity intensified. Consequently, the US

Army funded an extensive

research project at Purdue

University, beginning in

September 1947, to search

for low toxicity, high efficiency, and clean fire suppression agents.[1] Following an extensive analysis of over 65 candidates, Purdue identified a class of

compounds, now known as halons or HALogenated hydrocarbONS that provided efficient and clean extinguishment, while

also being low in toxicity. Following additional investigation,

halons 1301 (CF3Br) and 1211 (CF2BrCl) emerged as significant

commercial successes. The relevant physical properties for these

two compounds are compared in Table 1.

Civilian and military fire suppression systems that used halons

were widely specified and installed into the 1980s. The elevated safe

personnel exposure concentration and gaseous nature of Halon

1301 led to its finding principle use in total flooding applications

where a specific concentration of extinguishing agent is employed

to completely fill (“totally flood”) an enclosure, and provide extinIn the halon nomenclature, the

first digit represents the number

of carbon atoms in the molecule,

the second the number of fluorine

atoms, the third chlorine, fourth

bromine, and the last iodine.

Edward W. Tokarsky

Mark L. Robin

DuPont Co., Chemicals and Fluoroproducts Business

Wilmington, Delaware

Table 1. Comparison of Halon 1211 and 1301.

Halon 1211 Halon 1301

Primary Applications Handheld and Total Flooding Systems

Area Wheeled Extinguishers

Chemical Formula CBrClF2 CBrF3

Molecular Weight 165.4 148.9

Boiling point, °C -3.4 -57.7

Extinguishing Concentration, 4.1 3.5

% in air for heptane

Cardiac sensitization 0.5 5

NOAEL*, % in air

Cardiac sensitization 1 7.5

LOAEL†, % in air

Ozone Depletion 4 16

Potential (ODP)

Atmospheric Lifetime, yrs 15 65
The AMMTIAC Quarterly, Volume 6, Number 1 12 http://ammtiac.alionscience.com

guishment of a fire occurring anywhere within the protected enclosure. Halon 1211 became preferred for streaming applications

where the agent is directed as a stream towards a fire using portable

extinguishers or localized fixed systems.

The wide adoption of the halons was based on the fact that they

offered a unique combination of properties that could not be found

in any other compounds. Halons are clean agents that do not leave

any residue or require extensive cleanup following their use. They

are also highly effective fire suppressants, chemically and physically

stable, have acceptable toxicity, and were relatively low in cost. This

unique combination of properties makes the halons ideal agents for

the protection of expensive, sensitive, and mission-critical assets.

Halons found widespread use in an array of military applications,

including the protection of computer and command centers,

research test facilities, and an amalgam of land, sea, and air-based

military equipment. Table 2 lists a selection of military applications

that have employed halons.

A HALON ACHILLES HEEL IS DISCOVERED

In 1974, the work of Rowland and Molina called attention to the

significant effect that chlorine and bromine containing compounds

released into the atmosphere have on stratospheric ozone levels.[2]

This included the halons. Production of new halon was subsequently eliminated in developed countries beginning in January of 1994

under the Copenhagen amendments to the 1987 Montreal

Protocol. In addition, the United States’ passage of the Clean Air

Act of 1990 led to the development of the Significant New

Alternatives Policy (SNAP) Program, which evaluates and regulates

substitutes for ozone-depleting chemicals (ODSs). Under this

program the EPA is authorized to identify and publish lists of

acceptable and unacceptable substitutes for ODSs. The SNAP

program specifically lists fire suppression and explosion protection

as a category for review.

THE HALON TRANSITION ERA

Significant efforts have been made to find clean agent replacements

for halon extinguishants. Even though numerous substitutes have

been commercialized, halons often provide unparalleled overall

performance. For this reason, they are still specified in some critical

defense and civilian applications. Currently, however, there are no

facilities, worldwide, that produce halons for fire extinguishing

applications. As a result, supplies are obtained from stockpiles or

recycled from decommissioned systems.

The ideal halon replacement would be clean, leaving no residue,

and have a high fire extinguishing efficiency for Class A, B and C

fires, low chemical reactivity, and long term storage stability. It

should also be non-corrosive to metals, have a high material compatibility (metals, plastics, elastomers), low toxicity, and be environmentally acceptable (no contribution to ozone depletion or climate

change). To date, no halon replacement has been developed which

satisfies all of these requirements.

Table 3 lists the commercially available clean agent options for

the halons. For purposes of discussion and comparison they are

arranged into four groups: inert gases, hydrofluorocarbons (HFCs),

hydrochlorofluorocarbons (HCFCs), and perfluoroketones (PFKs).

INERT GASES

The inert gas agents listed in Table 3 extinguish fires by reducing the

atmospheric oxygen content from 21% to between 12 and 15%. At

these levels, most ordinary combustibles will not burn. Care must

be taken, however, since asphyxiation signs begin below 12%, with

oxygen levels below 10% being extremely dangerous. Inert gas

agents are clean since no corrosive residues form following extinguishment. They are also electrically non-conductive, chemically

non-reactive, have low toxicity, and do not contribute to ozone

depletion or climate change.

The inert gas agents cannot be compressed to liquids and, as a

result, can only be stored as high pressure gases. Thus, inert gas

extinguishing systems require the use of high pressure storage cylinTable 3. Clean agent options for halon replacement.

Chemical Class Designation Chemical Formula Applications Trade Name

Inert Gases IG-541 N2 (52%) + Ar (40%) + CO2 (8%) Total flooding Inergen®‡

IG-55 N2 (50%) + Ar (50%) Total flooding ArgoniteTM§

IG-01 Ar Total flooding ArgotecTM||

IG-100 N2 Total flooding N-100TM#

Hydrofluorocarbons (HFCs) HFC-227ea CF3CHFCF3 Total flooding, Streaming FM-200®**

HFC-125 CF3CF2H Total flooding FE-25TM††

HFC-23 CF3H Total flooding FE-13TM††

HFC-236fa CF3CH2CF3 Streaming FE-36TM††

Hydrochlorofluorocarbons (HCFCs) HCFC Blend B CF3CHCl

2 + CF4 + Ar Streaming Halotron®‡‡ I

Perfluoroketones FK-5-1-12 CF3CF2C(O)CF(CF3)2 Total flooding NovecTM§§ 1230

Table 2. Historical halon applications within the military.

Application Halon

Computer Centers 1301 & 1211

Command Centers 1301

Research Facilities 1301

Aircraft Engine Nacelles 1301 & 1211

Aircraft APU 1301 & 1211

Aircraft Dry Bay 1301

Aircraft Cargo Bay 1301

Armored Vehicles: Engine Compartment 1301 & 1211

Armored Vehicles: Crew Compartment 1301

Armored Vehicles: Portable Extinguisher 1301 &1211

Airfield Flightline & Crash Rescue Vehicle 1211

Naval Vessels: Machinery & Engine Space 1301

Naval Vessels: Electrical Compartment 1301

Naval Vessels: Flammable Liquid Storeroom 1301
The AMMTIAC Quarterly, Volume 6, Number 1 13 http://ammtiac.alionscience.com

ders and high pressure piping, which leads to increased system costs.

In addition, these systems require larger numbers of cylinders and

consequently require more storage space when compared to the

other clean agents, further increasing the cost of these systems.

HALOGENATED CLEAN AGENTS

Hydrofluorocarbons (HFCs) were initially developed, nearly 20

years ago, as environmentally friendly refrigerants since they do not

contain bromine or chlorine atoms in their molecular structure –

the two elements that contribute to stratospheric ozone depletion.

Some HFCs also proved to be clean, safe, and effective fire extinguishants. The HFC clean agents are gases at room temperature and

extinguish fire predominantly via heat absorption. In other words,

they remove heat from the fire until it can no longer be sustained,

and is extinguished. HFC agents are clean, electrically non-conductive, and characterized by low chemical reactivity, low toxicity, and

minimal environmental impact. The HFC clean agents can be

stored as liquefied compressed gases, requiring fewer cylinders and

storage space than the inert gas agents. Additionally, their use does

not require high pressure cylinders or piping.

HYDROCHLOROFLUOROCARBONS & PERFLUOROKETONES

Hydrochlorofluorocarbons (HCFCs) are similar to the HFCs in

most properties, but are characterized by a non-zero ODP; thus,

HCFCs are slated for eventual phaseout under the provisions of

the Montreal Protocol. The perfluoroketone agent differs from

the halons, inert gases, HFCs and HCFCs in that it is characterized by relatively high chemical reactivity and is a liquid at room

temperature.

A summary comparing the qualitative differences between the

extinguishant classes relative to Halon 1301 is found in Table 4. The

most significant feature illustrated by this table is that each class of

extinguishant has strengths and weaknesses. Selection must be based

on the criteria listed at the beginning of this discussion along with

detailed knowledge of the specific project requirements.

Table 4 shows that the HFCs, followed by the inert gases, provide the best overall combination of the properties desired in a

halon replacement. In fact, the most widely employed halon

replacements for military applications are FM-200® (HFC-227ea)

and Inergen® (N2/Ar/CO2). Table 5 compares the mass and volume

percent requirements for FM-200® and Inergen®. Class A Hazards

include ordinary combustible materials such as wood, cloth, paper,

rubber, and many plastics. Class B hazards include flammable liquids greases, oils, solvents, and flammable gases. Military applications currently employing clean agent halon replacements are listed

in Table 6 and shown in Figure 1.

CONCLUSION

Significant advances have been made in identifying replacement

products for Halons 1211 and 1301. To date, no alternative has

been developed that satisfies the requirements of an ideal halon

Table 4. Clean agent comparisons to Halon 1301.

Desirable Feature Halon 1301 Inert Gases HFC’s HCFCs PFKs

High weight efficiency + + + + + + +

Gas at ambient temperature ++++

Low chemical reactivity + + + + + + + + + + +

Low potential metallic corrosion ++++

Electrically non-conducting +++++

Low Toxicity + + + + + + + +

Lack of metabolism + + + + + + + + + +

Low agent cost + + + + + + + +

Low system cost + + + + + + + +

Low number of agent cylinders + +++

Low storage volume + +++

Low system footprint + +++

Low cylinder pressure rating + +++

Low manifold pressure rating + +++

Low positive/negative pressures during discharge + ++

Slow stratification + + + + + + + + +

Zero ozone depletion potential ++ +

Zero global warming potential +

VOC exempt (no contribution to smog) ++++

Table 5. Agent quantities required to protect a 100 m3 enclosure.

Agent Class A Hazard Class B Hazard

Vol % Wt., Kg Vol% Wt., Kg

IG-541 40.0 72.4 43.9 81.9

HFC-227ea 7.0 54.8 8.7 69.4

Table 6. Clean agents in military applications.

Application Agent

Computer centers HFC-227ea, IG-541

Command centers HFC-227ea, IG-541

Research facilities HFC-227ea, IG-541

Aircraft engine nacelles HFC-125

Aircraft APU HFC-125

Aircraft dry bay Inert gas generating systems

Armored vehicles: engine compartment HFC-227ea

Armored vehicles: crew compartment HFC-227ea/sodium bicarbonate

Airfield flight line & crash rescue vehicle HCFC Blend B

Naval vessels: machinery & engine space HFC-227ea

Naval vessels: electrical compartment HFC-227ea

Naval vessels: flammable liquid storeroom HFC-227ea
The AMMTIAC Quarterly, Volume 6, Number 1 14 http://ammtiac.alionscience.com

replacement. Accordingly, all of the current commercial options

come with trade-offs; HFCs provide the best overall combination of

desired properties, followed by the inert gas agents. This necessitates

a thorough understanding of system requirements and of the extinguishant’s performance envelope and hardware design. Although

research efforts continue in an attempt to identify viable halon

replacements, the attainment of a molecule that possesses all of the

desired properties of the ideal halon may not be achievable. Thus,

agent selection will continue to be application-specific, requiring

consideration of the performance, safety, and environmental characteristics of the different clean agents.

NOTES & REFERENCES *NOAEL is the volume concentration at which there are no observed

adverse effects under test conditions.

†LOAEL is the lowest observable adverse level concentration.

‡Inergen is a registered trademark of Ansul, which is a registered trademark

of Tyco Fire Suppression and Building Products.

§Argonite is a registered trademark of Ginge-Kerr Danmark A/S

Corporation.

|| Argotec is a registered trademark of Minimax GmbH Corporation.

#NN-100 is a trademark of Koatsu Co. Ltd.

**FM-200 is a registered trademark of E. I. Du Pont De Nemours and

Company Corporation.

††FE-25, FE-13, and FE-36 are trademarks of E. I. du Pont de Nemours

and Company.

‡‡Halotron is a registered trademark of American Pacific Corporation.

§§Novec is a registered trademark of the 3M Company Corporation.

[1] “Final Report on Fire Extinguishing Agents for the Period September 1,

1947 to June 30, 1950,” Purdue Research Foundation, Lafayette, IN, 1950.

[2] Molina, M.J., and F.S. Rowland, “Stratospheric Sink for Chlorofluoromethanes: Chlorine Atom Catalyzed Destruction of Ozone,” Nature,

Vol. 249, 1974.

[3] Robin, M.L., “The Role of HFCs in Global Fire Protection,” DuPont

Publication K-22197, 2009.

Edward W. Tokarsky, Ph.D., has been with DuPont for over 31 years and is currently a Senior Technical Consultant in the Chemicals and

Fluoroproducts business. During his career he has been involved with technical and marketing developments in Kevlar®, Nomex®, Teflon®, and

most recently, specialty fluorochemicals for fire extinguishants. In his current assignment, Dr. Tokarsky is responsible for DuPont’s line of clean agent

fire extinguishants.

Mark L. Robin, Ph.D., is a Senior Technical Services Consultant for DuPont whom has over 20 years of experience in the fire suppression industry. He has been extensively involved in the development, testing, and approval of halon alternatives; participates on numerous fire suppression

related technical committees; and is the recipient of a US EPA Stratospheric Ozone Protection Individual Award, presented for his efforts in the

development of halon replacements and international standards regulating their use.

Figure 1. DoD systems utilizing clean extinguishants.

Stryker: Crew compartment (HFC-227ea) F-22 Raptor: Engine Nacelle (HFC-125)

V-22 Osprey: Engine Nacelle (HFC-125) and Dry bay (Inert

Gas)

USS Ronald Reagan (CNV-76): Engine room (HFC-227ea)

USCG Patrol Boats: Engine Room (HFC-227ea) USMC AAAV: Crew Bay (HFC-227ea)

Command and Communication Centers, Research Facilities:

HFC-227ea, IG-541
AMMTIAC Directory

TECHNICAL MANAGER/COR

Dr. Khershed Cooper

Naval Research Laboratory

Code 6354

4555 Overlook Ave, SW

Washington, DC 20375

202.767.0181

Email: cooper@anvil.nrl.navy.mil

AMMTIAC DEPUTY DIRECTOR

Christian E. Grethlein, P.E.

201 Mill Street

Rome, NY 13440-6916

315.339.7009, Fax: 315.339.7107

Email: cgrethlein@alionscience.com

MATERIALS TECHNICAL DIRECTOR

Jeffrey D. Guthrie

201 Mill Street

Rome, NY 13440-6916

315.339.7058, Fax: 315.339.7107

Email: jguthrie@alionscience.com

DEFENSE TECHNICAL INFORMATION CENTER

(DTIC) POC

Glenda Smith, DTIC-I

8725 John J. Kingman Road, Ste 0944

Ft. Belvoir, VA 22060-6218

703.767.9127, Fax: 703.767.9174

Email: gsmith@dtic.mil

CONTRACTS FACILITATOR

Judy E. Tallarino

201 Mill Street

Rome, NY 13440-6916

315.339.7092, Fax: 315.339.7107

Email: jtallarino@alionscience.com

MANUFACTURING TECHNICAL DIRECTOR

Christian E. Grethlein, P.E.

201 Mill Street

Rome, NY 13440-6916

315.339.7009, Fax: 315.339.7107

Email: cgrethlein@alionscience.com

AMMTIAC DIRECTOR

Micheal J. Morgan

201 Mill Street

Rome, NY 13440-6916

937.431.9322 x103, Fax: 315.339.7107

Email: mmorgan@alionscience.com

TECHNICAL INQUIRY SERVICES MANAGER

Owen R. Conniff

201 Mill Street

Rome, NY 13440-6916

315.339.7026, Fax: 315.339.7107

Email: oconniff@alionscience.com

NON-DESTRUCTIVE EVALUATION

AND TESTING TECHNICAL DIRECTOR

David S. Forsyth

9063 Bee Caves Road

Austin, TX 78733-6201

512.263.2101 x223, Fax: 512.263.3530

Email: dforsyth@tri-austin.com

For a listing of upcoming materials, manufacturing & testing related events, please visit our website:

http://ammtiac.alionscience.com/calendar