Room Pressurization & Venting · 2013. 2. 13. · NFPA 2001 •NFPA 2001 (2004 Edition)NFPA 2001 (2004 Edition) – A.5.3.6 Enclosure pressures developed during the discharge of a

Room Pressurization & Room Pressurization & Room Pressurization & Room Pressurization & Room Pressurization & Room Pressurization & Room Pressurization & Room Pressurization &

Venting Venting Venting Venting Venting Venting Venting Venting

During Clean Agent DischargesDuring Clean Agent DischargesDuring Clean Agent DischargesDuring Clean Agent Discharges

Presented by:Presented by:Presented by:Presented by:

Jeff L. Harrington, P.E., FSFPEJeff L. Harrington, P.E., FSFPEJeff L. Harrington, P.E., FSFPEJeff L. Harrington, P.E., FSFPE

For:For:For:For:

FSSA 2007 Annual MeetingFSSA 2007 Annual MeetingFSSA 2007 Annual MeetingFSSA 2007 Annual Meeting

St. Petersburg Beach, FloridaSt. Petersburg Beach, FloridaSt. Petersburg Beach, FloridaSt. Petersburg Beach, Florida

© Harrington Group, Inc. 2007

February 12, 2007

Records Storage (HFCRecords Storage (HFCRecords Storage (HFCRecords Storage (HFCRecords Storage (HFCRecords Storage (HFCRecords Storage (HFCRecords Storage (HFC--------227ea)227ea)227ea)227ea)227ea)227ea)227ea)227ea)

• Concrete block wall Concrete block wall Concrete block wall Concrete block wall –––– 32 ft high32 ft high32 ft high32 ft high

• 30 ft protected height30 ft protected height30 ft protected height30 ft protected height

• Retention time over 20 minutesRetention time over 20 minutesRetention time over 20 minutesRetention time over 20 minutes

• Very small VVRVery small VVRVery small VVRVery small VVR

• Improper wall constructionImproper wall constructionImproper wall constructionImproper wall construction

– Low strength – less than 5 psf

February 12, 2007


February 12, 2007

• ReconstructionReconstructionReconstructionReconstruction

– Reinforced wall to >5 psf

– Added 2-way vents = 5,049 sq in– Manufacturer recommended vent area

• Empty Room VVR = 7.02• Full Room VVR = 10.8


February 12, 2007


February 12, 2007

Discharge Pressure LoadDischarge Pressure LoadDischarge Pressure LoadDischarge Pressure LoadDischarge Pressure LoadDischarge Pressure LoadDischarge Pressure LoadDischarge Pressure Load

• Discharge Pressure LoadDischarge Pressure LoadDischarge Pressure LoadDischarge Pressure Load

– Both inert and halocarbon clean agents

– Peak negative and/or positive pressure– Tight enclosure = higher pressure load

• High protected height = tighter enclosure• Long retention time = tighter enclosure

– Vent to Volume Ratio (VVR)

February 12, 2007

Pressure Load ManagementPressure Load ManagementPressure Load ManagementPressure Load ManagementPressure Load ManagementPressure Load ManagementPressure Load ManagementPressure Load Management

• Halocarbon Clean AgentsHalocarbon Clean AgentsHalocarbon Clean AgentsHalocarbon Clean Agents

– Protected height: LTE 75%

– Retention: 12 minutes maximum– VVR = 4.0 or greater (cm2/m3)

»OR– Provide 2-way relief venting

February 12, 2007

IGIGIGIGIGIGIGIG--------541 Tank Room541 Tank Room541 Tank Room541 Tank Room541 Tank Room541 Tank Room541 Tank Room541 Tank Room

February 12, 2007

Pressure Load ManagementPressure Load ManagementPressure Load ManagementPressure Load ManagementPressure Load ManagementPressure Load ManagementPressure Load ManagementPressure Load Management

• Inert Clean AgentsInert Clean AgentsInert Clean AgentsInert Clean Agents

– Provide 1-way relief venting

– Use proper pipe and fittings– Use proper pipe restraints

– Quality workmanship– Quality control process - effective

February 12, 2007

Enclosure StrengthEnclosure StrengthEnclosure StrengthEnclosure StrengthEnclosure StrengthEnclosure StrengthEnclosure StrengthEnclosure Strength

• Ability to resist the discharge Ability to resist the discharge Ability to resist the discharge Ability to resist the discharge

pressure dynamic load with some pressure dynamic load with some pressure dynamic load with some pressure dynamic load with some

safety factorsafety factorsafety factorsafety factor

• Typically measured in pounds per Typically measured in pounds per Typically measured in pounds per Typically measured in pounds per

square foot (psf) or square foot (psf) or square foot (psf) or square foot (psf) or PascalsPascalsPascalsPascals (Pa)(Pa)(Pa)(Pa)

– 1 psf = 48 Pa

– 5 psf = 239 Pa

February 12, 2007


• Wall Strength FactorsWall Strength FactorsWall Strength FactorsWall Strength Factors– Wall height

• Higher = weaker

– Material composition• Flexible = stronger• Rigid = weaker

– Tall & Rigid = Weak– Short & Flexible = Strong

February 12, 2007


• Typical ConstructionTypical ConstructionTypical ConstructionTypical Construction

– Gypsum wall board on metal studs• ½-in or 5/8-in wall board• 3-5/8 in or 6-in steel wall studs

– Common strength range• 5 psf to 15 psf

February 12, 2007



– Concrete Block or Masonry Units• More common for exterior wall sections• 4-in, 6-in, or 8-in common• Block plus brick veneer common

– Common strength range• Assume less than 5 psf unless proof of design

February 12, 2007



– Other • Large glass windows• Doors with safety pressure-release

February 12, 2007


• More on Gypsum on Studs (Case #1)More on Gypsum on Studs (Case #1)More on Gypsum on Studs (Case #1)More on Gypsum on Studs (Case #1)

– On a current project, the A&E designed the interior non-load bearing wall partitions to resist 5 psf.

– This is a common practice today

– Steel studs (3-5/8 in. were used)– ½ in. and 5/8 in. gyp board was used

February 12, 2007


• More on Gypsum on Studs (Case #2)More on Gypsum on Studs (Case #2)More on Gypsum on Studs (Case #2)More on Gypsum on Studs (Case #2)

– For an existing facility, a structural engineer determined that the wall strength was about 15 psf.

– Non-load bearing exterior walls

– Gypsum wall board on 6-in steel studs– Wall height = 14 ft.

February 12, 2007


February 12, 2007


• Information on Steel StudsInformation on Steel StudsInformation on Steel StudsInformation on Steel Studs

– Steel Stud Manufacturer’s Association• SSMA• www.ssma.com• Product Technical Information

February 12, 2007


February 12, 2007


• Information on Wood StudsInformation on Wood StudsInformation on Wood StudsInformation on Wood Studs

– American Wood Council• AWC• www.awc.org• Product Technical Information & Standards

February 12, 2007


February 12, 2007


• Information on MasonryInformation on MasonryInformation on MasonryInformation on Masonry

– Masonry Advisory Council• MAC• www.maconline.org• Product Technical Information & Standards

February 12, 2007


February 12, 2007

NFPA 2001NFPA 2001NFPA 2001NFPA 2001NFPA 2001NFPA 2001NFPA 2001NFPA 2001

• NFPA 2001 (2004 Edition)NFPA 2001 (2004 Edition)NFPA 2001 (2004 Edition)NFPA 2001 (2004 Edition)– 5.3.6* The protected enclosure shall have the

structural strength and integrity necessary to contain the agent discharge. If the developed pressures present a threat to the structural strength of the enclosure, venting shall be provided to prevent excessive pressures. Designers shall consult system manufacturer’s recommended procedures relative to enclosure venting.

February 12, 2007


• NFPA 2001 (2004 Edition)NFPA 2001 (2004 Edition)NFPA 2001 (2004 Edition)NFPA 2001 (2004 Edition)

– A.5.3.6 Enclosure pressures developedduring the discharge of a clean agent system are dependent on many variables including factors unique to each agent, system, and enclosure . Over- or underpressurization of the enclosure can occur during the discharge.

February 12, 2007


• NFPA 2001 (Next Edition NFPA 2001 (Next Edition NFPA 2001 (Next Edition NFPA 2001 (Next Edition ---- Proposed)Proposed)Proposed)Proposed)

February 12, 2007



– New Annex D – “Enclosure Evaluation”

– ROP Proposal 2001-100– ROC Accepted with deletion of last 4

paragraphs

February 12, 2007



– Proposed changes subject to NFPA membership approval in June, 2007

February 12, 2007

Q & AQ & AQ & AQ & AQ & AQ & AQ & AQ & A

Room Pressurization & Venting · 2013. 2. 13. · NFPA 2001 •NFPA 2001 (2004 Edition)NFPA 2001 (2004 Edition) – A.5.3.6 Enclosure pressures developed during the discharge of a

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