Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
---
title: Foam Fire Suppression Systems
…213 unchanged lines
## For aircraft hangars, the NFPA 409 group classification (Group I, II, III, or IV) shall be established before system type is selected.
−## The group classification governs whether the hangar uses a low-expansion foam-water system over the floor or a high-expansion total-flooding system, and it drives the structural and drainage coordination. Establishing the group late forces a system-type change that ripples through the entire design. {note}
−
```datasheet
label: NFPA 409 Aircraft Hangar Group (if applicable)
…8 unchanged lines
```
+## The group classification governs whether the hangar uses a low-expansion foam-water system over the floor or a high-expansion total-flooding system, and it drives the structural and drainage coordination. Establishing the group late forces a system-type change that ripples through the entire design. {note}
+
# Environmental and Service Conditions {toc}
## Foam concentrate shall be stored within the temperature range specified by the concentrate manufacturer, and freeze protection shall be provided where ambient conditions can fall below that range.
−## F3 concentrate storage temperature limits shall be verified against the manufacturer's submittal data.
−
−## Most AFFF concentrates are rated for storage between 35°F and 120°F (2°C to 49°C); F3 concentrates vary by manufacturer. Concentrate stored outside its rated range can stratify or lose performance, and frozen concentrate is unusable. {note}
−
−## Concentrate-wetted piping, tanks, and proportioner components shall be of materials compatible with the selected concentrate for the life of the system.
−
−## Concentrate lines shall be stainless steel or another manufacturer-approved corrosion-resistant material.
−
−## Foam concentrate - AFFF in particular - is corrosive to ordinary carbon steel. Specifying standard carbon-steel concentrate piping is a recurring defect that leads to early failure. {note}
−
−## Foam-contaminated firewater runoff shall be contained and managed in coordination with the civil engineer and the requirements of NFPA 30.
−
−## Discharged foam solution is regulated as hazardous waste in many jurisdictions and cannot be allowed to enter stormwater. The spill control and secondary containment required by NFPA 30 must be coordinated with the site drainage design before the system is approved. Failing to coordinate drainage and containment is a common cause of approval delay. {note}
−
```datasheet
label: Minimum Ambient Storage Temperature
…6 unchanged lines
```
+## F3 concentrate storage temperature limits shall be verified against the manufacturer's submittal data.
+
+## Most AFFF concentrates are rated for storage between 35°F and 120°F (2°C to 49°C); F3 concentrates vary by manufacturer. Concentrate stored outside its rated range can stratify or lose performance, and frozen concentrate is unusable. {note}
+
+## Concentrate-wetted piping, tanks, and proportioner components shall be of materials compatible with the selected concentrate for the life of the system.
+
```datasheet
label: Concentrate-Wetted Piping Material
…6 unchanged lines
```
+## Concentrate lines shall be stainless steel or another manufacturer-approved corrosion-resistant material.
+
+## Foam concentrate - AFFF in particular - is corrosive to ordinary carbon steel. Specifying standard carbon-steel concentrate piping is a recurring defect that leads to early failure. {note}
+
+## Foam-contaminated firewater runoff shall be contained and managed in coordination with the civil engineer and the requirements of NFPA 30.
+
+## Discharged foam solution is regulated as hazardous waste in many jurisdictions and cannot be allowed to enter stormwater. The spill control and secondary containment required by NFPA 30 must be coordinated with the site drainage design before the system is approved. Failing to coordinate drainage and containment is a common cause of approval delay. {note}
+
# System Type and Configuration {toc}
## The foam system type shall be selected to match the hazard geometry, fuel type, and governing code as established by the hazard analysis.
−## There is no universal foam system. A surface fire on an open spill is handled differently from a fire inside a fixed-roof tank, which is handled differently again from a fire in an enclosed hangar. The configuration below is the primary design fork, and it determines the discharge devices, the proportioner sizing, and the application rate tables that apply. {note}
−
```datasheet
label: Foam System Type
…8 unchanged lines
```
+## There is no universal foam system. A surface fire on an open spill is handled differently from a fire inside a fixed-roof tank, which is handled differently again from a fire in an enclosed hangar. The configuration below is the primary design fork, and it determines the discharge devices, the proportioner sizing, and the application rate tables that apply. {note}
+
## Foam expansion ratio shall fall within the band defined for the selected system type by NFPA 11.
−## NFPA 11 classifies foam by how much the finished foam expands relative to the foam solution: low expansion is less than 20:1, medium expansion is 20:1 to 200:1, and high expansion is 200:1 to 1,000:1. The expansion band follows from the system type and the discharge device; it is not independently selected. {note}
−
```datasheet
label: Foam Expansion Class
…6 unchanged lines
```
+## NFPA 11 classifies foam by how much the finished foam expands relative to the foam solution: low expansion is less than 20:1, medium expansion is 20:1 to 200:1, and high expansion is 200:1 to 1,000:1. The expansion band follows from the system type and the discharge device; it is not independently selected. {note}
+
## The discharge device shall be matched to the selected system type and listed for use with the selected concentrate.
−## Foam makers apply low-expansion foam to tank surfaces, high-expansion generators flood enclosed volumes, foam-water sprinklers and open spray nozzles cover deluge areas, and monitors or cannons project foam across open-air fuel-handling areas. Each device aspirates and expands the foam differently, so the device, the concentrate, and the proportioner must be a listed match. {note}
−
```datasheet
label: Primary Discharge Device
…9 unchanged lines
```
+## Foam makers apply low-expansion foam to tank surfaces, high-expansion generators flood enclosed volumes, foam-water sprinklers and open spray nozzles cover deluge areas, and monitors or cannons project foam across open-air fuel-handling areas. Each device aspirates and expands the foam differently, so the device, the concentrate, and the proportioner must be a listed match. {note}
+
# Proportioning {toc}
## The proportioning method shall be selected for the system's flow range and shall maintain proportioning accuracy across the full range of expected operating flows.
−## The proportioner injects concentrate into the water stream at the design ratio. The available methods - inline balanced-pressure, bladder-tank, around-the-pump, variable-flow balanced-pressure, and premixed storage - differ in how they hold ratio as flow changes. A balanced-pressure proportioner sized for a large flow will not hold ratio when only a fraction of the deluge heads operate, so the full flow-range analysis, not just the peak flow, governs the selection. {note}
−
−## The proportioning system shall deliver concentrate within ±30% of the nominal proportioning percentage at all design flows, per NFPA 11.
−
−## For a 3% system this means the delivered concentration shall remain between 2.1% and 3.9% across minimum, design, and maximum flow. A proportioner that meets accuracy only at peak flow but starves the foam at low flow does not satisfy this requirement. {note}
−
−## Concentrate storage volume shall be sized for the design proportioning percentage and the full minimum application time, with no credit for a lower percentage.
−
−## Under-sizing concentrate storage is a frequent and costly RFI: storage volume calculated at 1% when the system is designed at 3% leaves only a third of the required concentrate. Size the bladder tank or concentrate tank for the design percentage multiplied by the design solution flow and the full required application time, plus the manufacturer's reserve. {note}
−
```datasheet
label: Proportioning Method
…8 unchanged lines
```
+## The proportioner injects concentrate into the water stream at the design ratio. The available methods - inline balanced-pressure, bladder-tank, around-the-pump, variable-flow balanced-pressure, and premixed storage - differ in how they hold ratio as flow changes. A balanced-pressure proportioner sized for a large flow will not hold ratio when only a fraction of the deluge heads operate, so the full flow-range analysis, not just the peak flow, governs the selection. {note}
+
+## The proportioning system shall deliver concentrate within ±30% of the nominal proportioning percentage at all design flows, per NFPA 11.
+
+## For a 3% system this means the delivered concentration shall remain between 2.1% and 3.9% across minimum, design, and maximum flow. A proportioner that meets accuracy only at peak flow but starves the foam at low flow does not satisfy this requirement.
+
+## Concentrate storage volume shall be sized for the design proportioning percentage and the full minimum application time, with no credit for a lower percentage.
+
+## Under-sizing concentrate storage is a frequent and costly RFI: storage volume calculated at 1% when the system is designed at 3% leaves only a third of the required concentrate. Size the bladder tank or concentrate tank for the design percentage multiplied by the design solution flow and the full required application time, plus the manufacturer's reserve. {note}
+
+## The proportioner working pressure range shall be specified, and the proportioning system shall be selected to maintain accuracy across that entire range.
+
```datasheet
label: Proportioner Working Pressure Range
…9 unchanged lines
```
+## The concentrate storage type shall be specified, and its volume shall be sized for the design proportioning percentage, design solution flow, and full application time plus reserve.
+
```datasheet
label: Concentrate Storage Type
…10 unchanged lines
## The design application rate (density) and minimum application time shall be taken from the governing NFPA table for the hazard class and system type, and shall not be reduced below those minimums.
−## Application rate is the heart of foam design. For low-expansion surface application on hydrocarbons, NFPA 11 Table 5.3.3.1 sets a minimum of 0.10 gpm/ft²; most designs land between 0.10 and 0.16 gpm/ft² depending on hazard category. Foam-water sprinkler systems under NFPA 16 use a minimum of 0.16 gpm/ft² over the design area. High-expansion total flooding for aircraft hangars is sized by floor-area fill rate per NFPA 409 Table 5.2.1, typically 1.0 to 2.0 cfm/ft² at a 10:1 expansion ratio. The values below are the common design cases; the governing table for the actual hazard always controls. {note}
−
−## Minimum application time shall match the hazard, from 10 minutes for a loading-rack deluge to as much as 65 minutes for certain storage-tank hazards under NFPA 11 Chapter 5.
−
−## The application rate and the application time together fix the concentrate storage volume. Selecting the rate without the matching time, or vice versa, produces a storage tank that is too small for the design event. {note}
−
−## For NFPA 409 Group I hangars, low-expansion foam shall be applied at not less than 0.16 gpm/ft² over the entire floor area plus the approach, unless the AHJ approves an alternative.
−
−## Group III and IV hangars are typically protected by high-expansion generators sized for a one-foot-per-minute fill rate or as approved by the AHJ. The group classification, established earlier in Quality Assurance, selects which of these rules applies. {note}
−
```datasheet
label: Design Application Rate (Low-Expansion / Foam-Water)
…4 unchanged lines
step: 0.01
setpoints:
− - 0.10
+ - 0.1
- 0.16
− - 0.20
+ - 0.2
+ - 0.3
default: 0.16
```
+## Application rate is the heart of foam design. For low-expansion surface application on hydrocarbons, NFPA 11 Table 5.3.3.1 sets a minimum of 0.10 gpm/ft²; most designs land between 0.10 and 0.16 gpm/ft² depending on hazard category. Foam-water sprinkler systems under NFPA 16 use a minimum of 0.16 gpm/ft² over the design area. High-expansion total flooding for aircraft hangars is sized by floor-area fill rate per NFPA 409 Table 5.2.1, typically 1.0 to 2.0 cfm/ft² at a 10:1 expansion ratio. The values below are the common design cases; the governing table for the actual hazard always controls. {note}
+
+## Minimum application time shall match the hazard, from 10 minutes for a loading-rack deluge to as much as 65 minutes for certain storage-tank hazards under NFPA 11 Chapter 5.
+
+## The application rate and the application time together fix the concentrate storage volume. Selecting the rate without the matching time, or vice versa, produces a storage tank that is too small for the design event. {note}
+
+## For NFPA 409 Group I hangars, low-expansion foam shall be applied at not less than 0.16 gpm/ft² over the entire floor area plus the approach, unless the AHJ approves an alternative.
+
+## Group III and IV hangars are typically protected by high-expansion generators sized for a one-foot-per-minute fill rate or as approved by the AHJ. The group classification, established earlier in Quality Assurance, selects which of these rules applies. {note}
+
+## The high-expansion total-flooding rate for hangars shall be specified, based on the hangar group classification or as approved by the AHJ.
+
```datasheet
label: High-Expansion Total-Flooding Rate (Hangars)
…4 unchanged lines
step: 0.1
setpoints:
− - 1.0
− - 2.0
+ - 0.5
+ - 1
+ - 2
+ - 2.5
default: 1.0
```
…164 unchanged lines
default: One full design-discharge recharge
```