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

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Analysis and testing to identify and prevent unwanted hydraulic pressure transients in process piping
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Fauske & Associates fulfills the requirements of ISO/IEC 17025:2017 in the field of Testing

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Fauske & Associates fulfills the requirements of ISO 9001:2015
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Evaluate your process to identify combustible dust hazards and perform dust explosion testing
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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
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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Recent Posts

A Simple and Accurate Non-Equilibrium Two Phase Flashing Flow Model Compared to Safety Relief Valve Data

Posted by Fauske & Associates on 08.27.18

By Hans K. Fauske, D.Sc., Regent Advisor, Fauske & Associates, LLC

In contrast to the two-fluid models that require numerous assumptions and the corresponding closure equations, the simple model can be stated as:

Untitled-11 (1)

where G (kg m-2 s-1) is the two-phase flow rate including the effects of Subcooling (Gsc) and non-equilibrium, Y is the dimensionless independent variable ranging from 0 to 1 and G0 and G1 are the corresponding asymptotic flow rate limits. If all liquid exist at the stagnation condition, extensive data suggest that a simple length criterion L of the order of 100 mm characterizes the residence time requirement for approaching equilibrium flashing flow in ducts which are well described by the Equilibrium Rate Model (ERM), (Fauske, 1985). In this case Y in Eq. (1) represents the dimensionless length L+ = L/100 ranging from 0 to 1. For all specified stagnation conditions the easy to estimate G values with no arbitrary adjustable parameters are in remarkable agreement with available experimental data. An example is illustrated in Figure 1 comparing Eq. (1) with subcooled and saturated non-equilibrium flashing valve data.


0 – Subcooling saturated liquid at stagnation pressure P0 = 4.7 bar,Untitled-1-19and the saturated flow limits are Untitled-2-5 and Untitled-3-3
and the non-equilibrium flow rate from Eq. (1) is


is in excellent agreement with experimental data 0.42.

5°C Subcooling Tn = 144.5°C leads to a saturation pressure Ps = 4.0934 bar with P0 = 4.7 bar and
Untitled-6-1 and the saturated liquid flow limits are
and the non-equilibrium two-phase flow rate from Eq. (1) is
            or G/G20 = 14,589/27,131 = 0.5397, in excellent agreement with experimental data = 0.54.

 Figure 1 - Crosby Safety ValveReferences

“Bolle, J. et al., 1995, “Flashing Water Flow Through a Safety Valve,” J. Loss 
     Prev. Process Ind. 8(2), p. 111 (1995).
Fauske, H. K., 1985, “Flashing Flows: Some Practical Guidelines for Emergency
     Releases,” Plant/Operation. Prog. 4(3), pp.132-134 (July 1985).

For more information regarding relief system design, two-phase flow and other process safety engineering and testing, please contact or 630-323-8750


Figure 1




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