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Project Profile

Facility Siting: Fan Pressurization Testing for Shelter-In-Place Buildings

Read how we address complex facility siting hazards, including mitigating the risk of toxic/flammable gas infiltration into Shelter-In-Place buildings at petrochemical facilities.

Project Objectives

Facility Siting: Fan Pressurization Testing for Shelter in Place Buildings

Project Overview

Facility Siting addresses explosion, fire, and toxic hazards to occupied buildings. This project profile describes how our Extreme Loads and Structural Risk division provides blower door testing services to mitigate the risk of toxic/flammable gas infiltration into Shelter-In-Place buildings at petrochemical facilities. 

A site emergency response plan may call for Shelter-In-Place (SIP) in some situations where there is the potential for the building to be exposed to toxic and/or flammable releases.  

Emergency response planning may direct personnel in SIP buildings in the event of a toxic/flammable release. Often, this SIP practice can be as simple as 1) close doors and windows, 2) shut off the HVAC and 3) wait out the hazard. The hope is that the exterior hazard is neutralized prior to the environment inside the building becoming hazardous.

ABS Group evaluates toxic/flammable infiltration into buildings through analysis and fan pressurization testing to quantify hazards when conducting facility siting for shelter-in-place. 

Client Needs
  • Quantify and understand SIP conditions and hazards.
  • Perform fan pressurization testing (blower door testing) to measure leak rate under various conditions.
  • Predict toxic/flammable gas infiltration to determine emergency response timing for SIP.
  • Safeguard personnel through risk reduction and improving process safety performance.


Questions to Consider About Your Industrial Facility 

  • Do toxics/flammables reach my occupied buildings for selected scenarios?
  • Can my people evacuate the building or is it better to SIP?
  • What is toxic/flammable leak rate into the building?
  • How long can personnel SIP before the inside atmosphere becomes hazardous?
  • What can be done to identify principal leak paths and better seal the building?
  • What is the emergency response plan if occupants have to stop SIP and evacuate before the outdoor hazard is abated?

Facility Siting Solutions

Blower Door Testing

ABS Group provides a full spectrum of engineering services to assist in the evaluation and design of remediation for fire, explosion and toxic hazards as part of the facility siting study. Specific to this project profile, ABS Group regularly performs the following analysis and testing in-house to quantify and understand SIP conditions and hazards.

  • Perform dispersion modeling of selected scenarios to quantify toxic/flammable concentration over time, exterior to the building – computational fluid dynamic dispersion modeling (CFD) can also be provided for specific worst-case scenarios.
  • Consider various wind conditions – low wind condition makes the toxic cloud linger outside the building but suppresses infiltration into the building.  High wind conditions more readily dilute downwind toxic/flammable gas concentrations but result in a larger air infiltration rate into the building.
  • Perform fan pressurization testing (also known as "blower door testing") to measure leak rate under various conditions.
  • Predict toxic/flammable gas infiltration over time based on blower door testing and determine how many minutes until the atmosphere exceeds habitation criteria. Interior concentration vs time is plotted based on leak rate and exterior time-dependent conditions (i.e., outdoor toxic/flammable concentrations changing over time due to conditions at the release source).
  • Perform a visual diagnostic evaluation with infrared thermography and smoke pencils to identify opportunities to better seal the building.
  • Recommend sealing of the building based on testing and analysis.
  • Toxic/Flammable infiltration analysis can be updated after the building is modified and updated blower door testing performed.

Additional recommendations may include:

  • Positive air pressure and elevated stack - with analysis to set stack height
  • Toxic/flammable monitoring inside and out and strategies for leak detection including HVAC air intake shut down on detection of flammable/toxic gas
  • Appropriate emergency communications
  • Option to use interior safe rooms with a greater level of seal-tightness
  • Supplied air
  • Scrubber system to conditions air during an emergency
  • Evacuation route evaluation leaving building and escape PPE. This is a dose-based analysis that uses chemical-dependent probit values to predict probability of fatality.

Fan Pressurization Test Assembly (Exterior)

Fan Pressurization Test Assembly (Interior)

Thermal Imagery at Door

Toxic Vulnerability vs Time

Internal Gas Concentration vs Time

Value Delivered

Our Facility Siting services cover a wide range of explosion, fire and toxic release hazards that pose a threat to refining, petrochemical and specialty chemical process installations.

Employing blower door testing and gas infiltration calculations refines the typical, conservative assumptions made in facility siting studies. This provides our clients with more accurate information to make decisions on building/mechanical system upgrades and often results in cost savings. This service also provides a baseline for development of actionable recommendations and remediation for the hazard.

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