Combustible Dust Testing

Laboratory testing to quantify dust explosion and reactivity hazards

Safety Data Sheets

Develop critical safety data for inclusion in SDS documents

Gas and Vapor

Laboratory testing to quantify explosion hazards for vapor and gas mixtures

Classification of hazardous materials subject to shipping and storage regulations
Testing and consulting on the explosion risks associated with devices and processes which use or produce hydrogen
Safety Data Sheets

Develop critical safety data for inclusion in SDS documents

Thermal Stability

Safe storage or processing requires an understanding of the possible hazards associated with sensitivity to variations in temperature

Adiabatic Calorimetry
Data demonstrate the consequences of process upsets, such as failed equipment or improper procedures, and guide mitigation strategies including Emergency Relief System (ERS) design
Reaction Calorimetry
Data yield heat and gas removal requirements to control the desired process chemistry
Battery Safety

Testing to support safe design of batteries and electrical power backup facilities particularly to satisfy UL9540a ed.4

Safety Data Sheets

Develop critical safety data for inclusion in SDS documents

Cable Testing
Evaluate electrical cables to demonstrate reliability and identify defects or degradation
Equipment Qualification (EQ)
Testing and analysis to ensure that critical equipment will operate under adverse environmental conditions
Water Hammer
Analysis and testing to identify and prevent unwanted hydraulic pressure transients in process piping
Acoustic Vibration
Identify and eliminate potential sources of unwanted vibration in piping and structural systems
Gas & Air Intrusion
Analysis and testing to identify and prevent intrusion of gas or air in piping systems
ISO/IEC 17025:2017

Fauske & Associates fulfills the requirements of ISO/IEC 17025:2017 in the field of Testing

ISO 9001:2015
Fauske & Associates fulfills the requirements of ISO 9001:2015
Dust Hazards Analysis
Evaluate your process to identify combustible dust hazards and perform dust explosion testing
On-Site Risk Management
On-site safety studies can help identify explosibility and chemical reaction hazards so that appropriate testing, simulations, or calculations are identified to support safe scale up
DIERS Methodology
Design emergency pressure relief systems to mitigate the consequences of unwanted chemical reactivity and account for two-phase flow using the right tools and methods
Deflagrations (Dust/Vapor/Gas)

Properly size pressure relief vents to protect your processes from dust, vapor, and gas explosions

Effluent Handling

Pressure relief sizing is just the first step and it is critical to safely handle the effluent discharge from an overpressure event

FATE™ & Facility Modeling

FATE (Facility Flow, Aerosol, Thermal, and Explosion) is a flexible, fast-running code developed and maintained by Fauske and Associates under an ASME NQA-1 compliant QA program.

Mechanical, Piping, and Electrical
Engineering and testing to support safe plant operations and develop solutions to problems in heat transfer, fluid, flow, and electric power systems
Hydrogen Safety
Testing and consulting on the explosion risks associated with devices and processes which use or produce hydrogen
Thermal Hydraulics
Testing and analysis to ensure that critical equipment will operate under adverse environmental conditions
Nuclear Safety
Our Nuclear Services Group is recognized for comprehensive evaluations to help commercial nuclear power plants operate efficiently and stay compliant
Radioactive Waste
Safety analysis to underpin decomissioning process at facilities which have produced or used radioactive nuclear materials
Adiabatic Safety Calorimeters (ARSST and VSP2)

Low thermal inertial adiabatic calorimeters specially designed to provide directly scalable data that are critical to safe process design

Other Lab Equipment and Parts for the DSC/ARC/ARSST/VSP2 Calorimeters

Products and equipment for the process safety or process development laboratory


Software for emergency relief system design to ensure safe processing of reactive chemicals, including consideration of two-phase flow and runaway chemical reactions


Facility modeling software mechanistically tracks transport of heat, gasses, vapors, and aerosols for safety analysis of multi-room facilities


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With over 40 years of industry expertise, we have a wealth of process safety knowledge to share.

Recent Posts

Evaluating the Flammability Hazards of Liquid Vapors

Posted by Fauske & Associates on 10.07.13

By: Paul Osterberg, Manager, Flammability Testing, Fauske & Associates, LLC

Flammability Limits (LFL, UFL)With the growing concern of fires or explosions resulting from processing or handling hazardous material, it is important to characterize the flammable properties of that material. The flammability properties of fuels have been extensively studied for many years and are relatively well understood. Essentially, there are three elements required for a fire or an explosion to occur: a fuel, an oxidizer, and an ignition source. Through removal of one of these requirements, a fire/explosion will not occur. However, eliminating the ignition source as the sole means of fire/explosion prevention of hazardous chemicals is not a practical means of prevention due to flammable vapors having very low minimum ignition energies as well as numerous different ignition sources (known and unknown). Therefore, other means are necessary for reducing the risk of a fire/explosion. These revolve around moderating the fuel and oxidizer concentration to avoid a flammable concentration of gases/vapors.

In the chemical industry, processing and handling of chemicals could result in the formation of a flammable or explosive atmosphere. For liquid chemicals, this may occur at temperatures other than at ambient conditions. Figure 1 shows the relationship between the flammable properties of a combustible chemical and how they are related to temperature.

Figure 1: Temperature Effects on a Combustible Mixture (Crowl, 2003)

Temperature effects on a Combustible Mixture

As you increase temperature and move along the vapor pressure curve for a flammable substance, there becomes a point where the concentration of the vapor is sufficient for producing a flammable mixture. This temperature is commonly known as the Flash Point (FP). In theory, the lower flammability limit (LFL) should intersect the vapor pressure curve at the flashpoint temperature; as a result this temperature is also referred to as the Lower Temperature Limit of Flammability (LTFL). However, these two temperatures, FP and LTFL, may not always be observed to be similar with experimental data. Knowledge of the disparity between these two points will help better assess the flammability hazards of a specific chemical as well as help implement the proper safety precautions during handling.

To understand the variation between the lower temperature limit of flammability and the flash point, tests were performed to compare the results. The lower temperature limit of flammability tests were conducted using ASTM E1232 “Standard Test Method for Temperature Limit of Flammability of Chemicals” modified to be conducted in a 5.3-L stainless steel spherical vessel using a fuse wire ignition source for safety and environmental purposes. The criterion for a positive ignition was a 7% pressure rise above the starting pressure. The flash point tests were performed per ASTM D3278 “Standard Test Methods for Flash Point of Liquids by Small Scale Closed-Cup Apparatus”. These tests were performed on 4 different chemicals and their results are summarized in Table 1.

Table 1: Flash Point and Lower Temperature Limit of Flammability Results


Flash Point (°C)


Organosulfur compound



Lactam Ring compound



Pyridine compound 1



Pyridine compound 2



The deviation between the values determined for these two tests is a result of differences in the test apparatus and methodology used in each of these experiments. Flammability limits are influenced by numerous factors and offer an explanation into the differences between the two test results:

1. Vessel size and geometry – As the size of the vessel increases, the heat losses to the vessel wall becomes negligible. Through minimizing heat losses to the vessel wall, more heat is transferred to the combustion reaction, therefore, promoting flame propagation. This results in a widening of the flammable region and combustion can occur at lower temperatures.

2. Ignition source location – A lower ignition source location in a vessel has shown to widen the flammable region as compared to a central ignition source location (Van den Schoor, Norman & Verplaetsen, 2006). With a lower ignition source, a larger percentage of the combustible mixture participates in the combustion reaction with minimal heat losses to the wall, thereby, resulting in a high pressure increase.

3. Homogeneity of mixture – Slight changes in the vapor concentration could result in a mixture becoming flammable or not flammable. In the LTFL tests, the vapor mixture is stirred to provide a homogenous mixture of the fuel in air unlike the flash point tests where the vapor space is not stirred and thus concentration gradients my form. Furthermore, the LTFL tests provide a more uniform heating of the vessel as well as a longer mixing time to allow the vapor and the liquid to reach equilibrium. All of these factors will impact the concentration of the fuel in the vapor space, thereby, influencing the flammability results.

4. Flame propagation – Generally, the flammable region is wider for upward flame propagation than for downward flame propagation due to flame buoyancy. Tests performed in the 5.3L vessel measures upward flame propagation as compared to the flash point tester which is measuring downward flame propagation (EU-Project SAFEKINEX). This wider range means that the LTFL will occur at a lower temperature than the FP.

These results demonstrate that it is imperative to fully characterize the flammability hazards of chemicals. The use of the flash point by itself may not always be sufficient in providing proper safety precautions to avoid flammable temperatures when assessing the hazards of flammable liquids. As shown from the LTFL and FP tests, there can be large deviations between the two values. Therefore, the use of a safety margin with the flash point value may not always be adequate. A better approach would be to conduct a LTFL test to assess the temperature at which there is sufficient vapor for flame propagation.

For more information, contact AnnMarie Fauske at, 630-887-5213

Crowl, D.A. (2003). Understanding Explosions. New York: American Institute of Chemical Engineers.
EU-Project SAFEKINEX. Report on the experimental factors influencing explosion indices determination. Programme "Energy, Environment and Sustainable Development", Contract No: EVG1-CT-2002-00072, 2003-2006.
Van den Schoor, F., Norman, F., & Verplaetsen, F. (2006). Influence of the ignition source location on the determination of the explosion pressure at elevated initial pressure. Journal of Loss Prevention in the Process Industries, 459-462.

Topics: Combustible Dust, Flammability, Testing


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