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

UN-DOT
Classification of hazardous materials subject to shipping and storage regulations
Hydrogen
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
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Identify and eliminate potential sources of unwanted vibration in piping and structural systems
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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
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Testing and analysis to ensure that critical equipment will operate under adverse environmental conditions
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Our Nuclear Services Group is recognized for comprehensive evaluations to help commercial nuclear power plants operate efficiently and stay compliant
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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

FERST

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

FATE

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

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Recent Posts

FATE Facility Modeling of Airborne Virus Transmission

Posted by Fauske & Associates on 09.03.20

Written By Jim Burelbach, PhD, CCO, Fauske & Associates LLC

The current pandemic due to SARS-CoV-2, the virus that causes COVID-19, has challenged us to re-think everyday activities. One critical aspect that is vital for a safe return to “normal” is an understanding of how SARS-CoV-2 is transmitted within a building or facility, i.e. airborne aerosol transmission. The below example illustrates how the FATETM software is easily applied to a building comprising interconnected, well-mixed regions. The results illustrate specific actions that can help minimize virus transmission by reducing the amount of virus aerosols within a building.

The FATE (Flow Aerosol Thermal and Explosion) Facility software, developed by Fauske & Associates, LLC, is a versatile tool for analyzing the transient behavior of facilities and processes during normal and off-normal conditions. It has been used in the chemical and nuclear industries to assess fire and smoke transport, hydrogen transport and accumulation, and to predict pressure and temperature behavior of nuclear waste packages. Learn more about these applications by downloading our whitepaper.

A unique feature of FATE is its ability to characterize and track aerosols. This capability lends itself to quantification of hazards from aerosol particulate released under off-normal process conditions. FATE models the transport of aerosol particles from an emission source through a facility and into the environment, accounting for any settling, impaction, or filtration which may occur. While it has historically been used to model industrial hazards (chemical and radiological) the software is general enough that it can track biological aerosols, such as SARS-CoV-2.

Multi-Region Example Model

Consider the potential for virus aerosol transmission in an interconnected, multi-region facility with a shared ventilation system. An example model is illustrated in Figure 1. This example considers two rooms connected by a doorway and a shared ventilation system and includes features found in most ventilation systems which recondition, filter, and recycle the ventilation air. The aerosol source (an infected asymptomatic person) is treated as a constant rate emitter of aerosols developed through normal speech.
Within each room a healthy individual is represented by two regions (the air gap under a mask, if worn, and the lungs) and three junctions (the mask itself, the respiratory tract, and the exhale path). All virus aerosols that are inhaled are assumed to attach to the respiratory tract and pose a risk of infecting a healthy individual. A third individual is assumed to show up later and represents the possibility of virus transmission to someone who arrives in the building just after the other three individuals have left, but who can be exposed to a suspended aerosol that continues to be recirculated via the ventilation system.


The model uses published values for the airborne viral emission rate of SARS-CoV-2, measured droplet size and concentration in exhaled air representative of normal speaking, and the reported inhalation rate for light exercise. The model also considers deactivation of airborne virus based on published estimations of the half-life of SARS-CoV-2 in aerosols. The infectious dose for SARS-CoV-2 is currently not known and is estimated here based on a previous study related to SARS-CoV-1.

Figure 1 Multi-region model for airborne virus transmission

Figure 1 Multi-region model for airborne virus transmission

Example Results

The virus emitter (an infected person) and healthy Individual 1 are both in Room 1 (680 m3) for an eight-hour shift. A second, smaller room (136 m3) connects to Room 1 through a door. Individual 2 occupies Room 2. Both rooms share a ventilation system which provides four air changes per hour (ACH), with half of the air being recirculated. Four cases are analyzed:

1. with no ventilation and no masks,

2. with ventilation and no masks,

3. with a HEPA filter on the recirculated air and no masks, and

4. with both a HEPA filter and masks.

Figure 2 shows the distribution of aerosol mass for Case 2, with active ventilation but no masks. The aerosol removal rates by gravitational settling and ventilation to the environment are nearly identical. Aerosol removal by virus deactivation is significant, albeit smaller than by gravitational settling or ventilation. Although the aerosol source is in Room 1, the aerosols are transported to Room 2 by recirculated air through shared ventilation ducts, and Individual 2 in Room 2 receives appreciable dose.

After the infected person leaves the building, the aerosol concentrations decay exponentially. Individual 3 enters Room 1 at 8 hr and is exposed to remaining virus aerosols, receiving a small but non-negligible dose. After 16 hours the three healthy individuals have accrued an infection risk of 12.9%, 4.1%, and 0.5%, respectively. Table 3 summarizes the results for all four cases. The effectiveness of various measures taken to reduce the virus transmission is illustrated in Figure 3. As expected, ventilation, with HEPA filters for recirculated air, and wearing masks reduce the infection risk. Without HEPA filters, recirculated air can spread virus aerosols to other rooms sharing the same ventilation system.

Figure 2 Time history of aerosol mass distribution for Case 2

Figure 2 Time history of aerosol mass distribution for Case 2

Table 1 Summary of dose and infection risk results

Table 1 Summary of dose and infection risk results

Figure 3 Infection risk (blue: Dose 1, orange: Dose 2, grey: Dose 3)

Figure 3 Infection risk (blue: Dose 1, orange: Dose 2, grey: Dose 3)

Conclusions

A mechanistic approach is presented to quantify airborne transmission and infection of SARS-CoV-2 using the facility modeling code FATE. Some key information about the pathogen such as the infectious dose of SARS-CoV-2 is not known, and the infection risks reported here are based on specific model assumptions. FATE can be used to quantify the effectiveness of various measures taken to reduce the airborne transmission of the virus as the model is easily modified to represent different building configurations and ventilation networks. Further technical details are provided by Kennedy et al. (2020)1.

The FATE model presented here demonstrates that for a multi-room facility, ventilation, with HEPA filters for recirculated air, together with wearing masks, reduces the infection risk. Without HEPA filters, the recirculated air can spread virus aerosols to other rooms sharing the same ventilation system. The FATE model is easily modified to accommodate alternate system design or performance characteristics to quantify the benefit of system modifications in reducing infection risk.

To read an extended version of this article please read our Summer 2020 Process Safety Newsletter. If you'd like to speak to a Fauske team member about the FATE software, feel free to contact us!

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Sources:

1. Kennedy, M., Lee, S.J., and Epstein, M., 2020, “Modeling Aerosol Transmission of SARS-CoV-2 in a Multi-Room Facility,” submitted for publication in the Journal of Loss Prevention in the Process Industries.

Topics: FATE

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