Pressure Relief Estimator

The following information is provided as a service to users of this website and does not constitute an endorsement by Guardian Services Inc. of the products described below.

The FSSA has released the second edition of the Pressure Relief Vent guide and software. The second edition of the guide and software includes estimating equations, tables and graphs for both customary U.S. units (PSI, inches, feet) and SI units (pascals, centimeters, meters). The guide also includes enhanced sections explaining the derivation of the data upon which the estimating techniques are based.

For further detail on this guide and companion software, please read the FSSA Press Release below.

The second edition of the “Guide to Estimating Enclosure Pressure and Pressure Relief Vent Area for Applications Using Clean Agent Fire Extinguishing Systems” and the companion computer program, the FSSA PRV Estimator (Version 1.0.2), are now available from the Fire Suppression Systems Association (FSSA). Click here to go to the FSSA website.

The above link is provided solely for the convenience of our visitors. GSI is not responsible for the content of the information on linked web pages.

The 2008 edition of NFPA^® 2001, Standard on Clean Agent Fire Extinguishing Systems, requires that the following items be included on working plans for clean agent fire extinguishing systems:

“5.1.2.2 (10) For an enclosure protected by a clean agent fire extinguishing system an estimate of the maximum positive and maximum negative pressure, relative to ambient pressure, expected to be developed upon the discharge of agent.”

“5.1.2.2 (28) The pressure relief vent area, or equivalent leakage area, for the protected enclosure to prevent development, during system discharge, of a pressure difference across the enclosure boundaries that exceeds a specific enclosure pressure limit.”

Thanks to the cooperative efforts of several fire protection equipment manufacturers and interested parties, experimental data has been obtained for the purpose of developing a guide to meet these requirements.

The guide book, developed by the Fire Suppression Systems Association technical committee, discusses the NFPA^® 2001 requirements as well as the experimental data. The guide book also provides equations, tables and charts which may be used to estimate peak pressures and relief vent areas for discharges of FK-5-1-12, HFC-23, HFC-125, HFC-227ea, IG-55, IG-100 and IG-541 for the range covered by the experimental data.[i]

In addition to the printed guide, the FSSA offers a companion computer program based on the estimating equations from the guide book.[ii] The FSSA PRV Estimator computer program automates the process of estimating peak pressure and related leakage area for discharges of clean agents into enclosures. Estimates are obtained more quickly with greatly reduced chance of arithmetic errors by using the computer program.

The “Guide to Estimating Enclosure Pressure and Pressure Relief Vent Area for Applications Using Clean Agent Fire Extinguishing Systems” and the companion computer program, the FSSA PRV Estimator, are now available from the Fire Suppression Systems Association (FSSA). Click here to go to the FSSA website.

The above link is provided solely for the convenience of our visitors. GSI is not responsible for the content of the information on linked web pages.

[i] For inert gases, the maximum peak positive pressure covered by the test data is 20 PSF. For liquefied compressed gas agents, the maximum peak pressures varied by agent as follows: FK-5-1-12 peak positive 5 PSF, peak negative 25 PSF; HFC-23 peak positive 30 PSF, peak negative did not apply; HFC-125 both peak positive and peak negative 10 PSF; HFC-227ea peak positive 8 PSF, peak negative 20 PSF. Results are not to be extrapolated beyond the respective pressure data limits. Additional limitations apply.

[ii] The information in the guide and the related software does not supersede the manufacturer’s guidance—rather the information is presented to supplement the guidance provided by the respective system manufacturers. Guidance from the system manufacturer should always be followed and used for purposes of system design, installation, operation and maintenance.

NOTE that gaseous clean agent fire extinguishing systems as installed in the field are capable of producing peak pressures well above those covered by the test data used for the FSSA PRV estimator. ALWAYS CONSULT THE SYSTEM MANUFACTURER FOR DESIGN INFORMATION.