Combustible Dust Testing

Laboratory testing to quantify dust explosion & reactivity hazards

Flammable Gas & Vapor Testing

Laboratory testing to quantify explosion hazards for vapor and gas mixtures

Chemical Reactivity Testing

Laboratory testing to quantify reactive chemical hazards, including the possibility of material incompatibility, instability, and runaway chemical reactions

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 safety handle the effluent discharge from an overpressure event

Thermal Stability

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

UN-DOT

Classification of hazardous materials subject to shipping and storage regulations

Safety Data Sheets

Develop critical safety data for inclusion in SDS documents

Biological

Model transport of airborne virus aerosols to guide safe operations and ventilation upgrades

Radioactive

Model transport of contamination for source term and leak path factor analysis

Fire Analysis

Model transport of heat and smoke for fire analysis

Flammable or Toxic Gas

transport of flammable or toxic gas during a process upset

OSS consulting, adiabatic & reaction calorimetry and consulting

Onsite safety studies can help identify explosibility and chemical reaction hazards so that appropriate testing, simulations, or calculations are identified to support safe scale up

Mechanical, Piping, and Electrical

Engineering and testing to support safe plant operations and develop solutions to problems in heat transfer, fluid flow, electric power systems

Battery Safety

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

Hydrogen Safety

Testing and consulting on the explosion risks associated with devices and processes which use or produce hydrogen

Spent Fuel

Safety analysis for packaging, transport, and storage of spent nuclear fuel

Decommissioning, Decontamination and Remediation (DD&R)

Safety analysis to underpin decommissioning process at facilities which have produced or used radioactive nuclear materials

Laboratory Testing & Software Capabilities

Bespoke testing and modeling services to validate analysis of DD&R processes

Nuclear Overview

Our Nuclear Services Group is recognized for comprehensive evaluations to help commercial nuclear power plants operate efficiently and stay compliant.

Severe Accident Analysis and Risk Assessment

Expert analysis of possible risk and consequences from nuclear plant accidents

Thermal Hydraulics

Testing and analysis to ensure that critical equipment will operate under adverse environmental conditions

Environmental Qualification (EQ) and Equipment Survivability (ES)

Testing and analysis to ensure that critical equipment will operate under adverse environmental conditions

Laboratory Testing & Software Capabilities

Testing and modeling services to support resolution of emergent safety issues at a power plant

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 (DSC/ARC supplies, CPA, C80, Super Stirrer)

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

Blog

Our highly experienced team keeps you up-to-date on the latest process safety developments.

Process Safety Newsletter

Stay informed with our quarterly Process Safety Newsletters sharing topical articles and practical advice.

Resources

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

Advanced Reactive System Screening Tool

ARSST-diagram-1

ARSST Background

Fauske & Associates, LLC's (FAI) Advanced Reactive System Screening Tool (ARSST™) is a low thermal-inertia calorimeter used to obtain critical upset process design data. The ARSST, while not as versatile as the VSP2, is both easier to use and less expensive to own and operate. We use the ARSST every day in our fully equipped thermal hazards laboratory, and we also manufacture the instrument and support its use by colleagues around the world.

As the name implies, the ARSST is well suited for basic process safety screening tests, particularly if one has only limited knowledge of the material being tested. ARSST technology was originally developed as a short-cut alternative to VSP2 testing. ARSST tests are easy to perform and require little specialized training. The tests generally are much quicker to set up than VSP2 tests, and the cost of consumables is low. The sample size is relatively small (several grams), which is an advantage during early process development when material can be scarce, or when very energetic materials are encountered, or when decomposition products are particularly hazardous and call for special cleanup procedures like gas scrubbing and acid neutralization. Typically, an ARSST test uses about a 10 ml sample, although samples as small as 1 g have been successfully tested.

ARSST tests are normally performed in what is called “open cell” mode. In open cell testing, vaporization (boiling) is suppressed by imposing an initial nitrogen gas “pad” in the containment vessel. For example, an inert gas pad pressure of 300 psi (20 bar) is typically enough to substantially increase the boiling point of the liquid reactants, such that there is negligible loss of reactants during the test. In fact, through numerous DIERS round robin exercises we have demonstrated excellent agreement between open cell ARSST data and closed cell VSP2 data, in particular with regard to data for vent sizing.

If non-condensable gas is generated in an ARSST test, then it accumulates in the surrounding containment vessel (350 or 450 ml) and the molar rate of gas generation is readily estimated using the measured pressure rise rate and the ideal gas law. Note that open cell testing is the recommended approach for gassy systems, which would be difficult to accommodate in a light weight closed cell due to extremely high pressures, gas volume uncertainty, and solution effects. Although VSP2 tests can also be done in open cell mode, the ARSST is often preferred for gassy decompositions simply because there is less material to handle and clean up. A closed cell ARSST option is also available and is useful for certain screening applications but it is not suitable for vent sizing data.

ARSST-employee-in-lab

The ARSST can be used to demonstrate whether tempering (boiling) at the relief set pressure is sufficient to suppress a runaway reaction. This is done by running the open test at the relief set pressure, say Pset = 15 psi (1 bar), by using a 15 psi (1 bar) pad rather than 300 psi (20 bar). One such example is an organic peroxide/solvent solution where a sustained fire heats the mixture and then boils off the solvent, during which time there may be some decomposition of the peroxide. If there is insufficient solvent latent heat available, then following solvent boil off the subsequent decomposition rate of the remaining peroxide heel is inferred directly from the measured pressure rise rate. The ARSST is well suited for direct fire simulation testing (up to 30ºC/min)

Liquid can be added directly to the ARSST test cell during a test using a fill tube. Samples are agitated using a magnetic stirrer. Test cells are normally made of lightweight glass to achieve a low phi-factor. It is also possible to use a heavier metal cell such as an ARC bomb, although this is not common because the associated high phi-factor means the data are not directly scalable.

ARSST data are used to model such upset scenarios as loss of cooling, loss of stirring, mischarge of reagents, mass-loaded upset, batch contamination and fire exposure heating. This easy-to-use and cost-effective calorimeter can quickly and safely identify potential reactive chemical hazards. ARSST data yield critical rates of temperature and pressure rise during a runaway reaction, thereby providing reliable energy and gas release rates which can be applied directly to full scale process conditions.

ARSST Benefits

The ARSST represents Minimum Best Practice and is based on established DIERS technology which is recognized by OSHA as an example of good engineering practice. This easy-to-use device is capable of quickly generating low phi-factor data for DIERS vent sizing and is an excellent tool for industry as well as any university chemistry or chemical engineering lab for research or unit operation studies. The ARSST enables users to quickly obtain reliable adiabatic data which can be used for a variety of safety applications including vent sizing, characterization of material compatibility, thermal stability and reaction chemistry. Test data include adiabatic rates of temperature and pressure change which, due to the low thermal inertia, can be directly applied to process scale.

Features and Applications

ARSST & Benchtop Stirrer

The ARSST design lets you directly simulate most process upset conditions including:

  • Loss of cooling or agitation
  • Accumulation or mischarge of reactants
  • Contamination of batch
  • Thermally initiated decomposition
  • External heating or fire exposure

Testing configurations are limited compared to the more versatile VSP2, but the ARSST has advantages in terms of small sample size, glass test cell, and ease of setup for quickly screening new or existing processes and generating the minimum safety data for applications such as:

  • Solids or liquids
  • In-situ liquid/gas dosing or sampling
  • Energetic materials

ARSST data allow you to quickly screen for hazardous chemical reactions and estimate key process safety parameters including:

  • Required size of Emergency Relief System (ERS)
  • Adiabatic temperature and pressure rise rates (dT/dt, dP/dt)
  • Total adiabatic temperature rise (ΔTad)
  • Heat of reaction or mixing
  • Time-to-maximum-rate (TMR) and SADT assuming simple kinetics

Contact us to discuss your process safety applications and obtain a customized ARSST quote.

ARSST Resources & Guides

Advanced Reactive System Screening Tool (ARSST)
ARSST - Things to Check to Perform a Successful Test
Why Consider Closed Cell ARSST Operation?
Exploring ARSST As A Tool For Education With Industrial Relevance
10 Tips for Setting up an ARSST Test to Yield Good Thermal Data