Clean Air, Sealed In
A sealed, pressure-tested filtration system so your shelter stays breathable when outside air is not.
What Goes Wrong
A blower rated for a smaller volume cannot sustain positive pressure, so contaminated air finds its way in through gaps and door seals.
System capacity is calculated from the bunker’s interior volume and occupancy count, not a catalog default or rough estimate.
Intake ducting run through the wall without a rated collar lets unfiltered air bypass the housing entirely, regardless of filter grade.
Every wall penetration is sealed with a rated collar so all intake air passes through the filter housing before entering the shelter.
A system that is never pressure-tested after installation may appear functional but fail to hold positive pressure when the door is closed.
A pressure reading with the door closed confirms the shelter holds positive pressure before the installer signs off the job.
Montana wildfire smoke loads activated carbon and HEPA H13 media faster than most scenarios, making a generic replacement schedule inadequate.
Cartridge replacement intervals are set around wildfire smoke load and usage hours, then documented at handover for the owner’s reference.
System Scope
Each component is specified and installed as part of a complete, sealed system, not assembled from unmatched parts.
The intake is cut through the bunker wall and sealed with a rated collar so no air bypasses the filter housing.
The housing is positioned for access during cartridge changes and mounted to prevent vibration loosening the seal over time.
Filter cartridges are selected for the contamination scenarios the shelter is designed for, including particulates and chemical vapors.
Metal ducting connects intake to housing to blower, with the exhaust vent separated from the intake to prevent recirculation.
Supply register airflow is measured and a pressure test confirms positive pressure is maintained with the shelter door closed.
Swap worn HEPA H13 or carbon cartridges without disturbing the housing.
Resize or reseal an undersized or aging filtration setup.
Check intake collars and duct joints for bypass gaps.
How It Works
A filtration system that is correctly sized but poorly sealed at the intake or ducting joints provides far less protection than the filter rating suggests.
Sizing comes first. The system is specified for the bunker’s interior volume, the number of occupants, and the planned duration of use. An undersized blower cannot maintain positive pressure; an oversized one cycles too fast for the filter media to capture fine particulates effectively. Montana wildfire smoke seasons are a concrete sizing reference point, smoke particulates load activated carbon and HEPA H13 media faster than most other contamination scenarios, so filter cartridge replacement intervals are planned around that reality.
Installation follows a fixed sequence: filter housing is mounted and sealed, intake penetration through the bunker wall is sealed with a rated collar, metal ducting connects the intake to the housing and the housing to the blower, and the exhaust vent is positioned for separation from the intake. Every penetration through the shelter wall is sealed to prevent bypass, unfiltered air entering around the duct defeats the system regardless of filter quality. Rural Montana ranch properties with large underground footprints require careful duct routing to maintain airflow balance across the space.
Commissioning includes an airflow measurement at the supply registers and a pressure test confirming the shelter holds positive pressure with the door closed. Positive pressure means air moves outward through any gap rather than inward, which is the operating principle that makes the sealed intake design effective. Filter cartridge replacement is scheduled based on usage hours and seasonal contamination load, and the replacement interval is documented as part of the handover.
Why Choose Us
Scope clarity and local installer accountability, not generic ventilation advice, are what make the difference on a sealed underground system.
Site access, soil conditions, occupancy, and system requirements are reviewed before an installer is contacted.
Enquiries are scoped for Montana sites, never quoted blind like an out-of-state job.
The quote covers intake, housing, ducting, and commissioning separately so you see exactly what each stage costs.
Equipment access, drainage grading, and soil bearing are identified in the scope review, not discovered on installation day.
The installer documents the filter replacement interval and system specs at handover so maintenance is straightforward.
The Process
01
Tell us the bunker volume, occupancy, and site location so the scope review can begin with the right inputs.
02
We clarify the scope, flag any rural site considerations, and move the enquiry to a phase-by-phase quote.
03
The installer fits, seals, and pressure-tests the system, then hands over documented filter intervals before leaving the site.
Pricing Estimates
| Job | Typical cost |
|---|---|
| Basic filtration unit install | $8,000-$20,000 |
| Mid-range CBRN system install | $20,000-$45,000 |
| High-capacity bunker filtration system | $45,000-$95,000 |
Tell us the bunker volume, the site location, and what the shelter needs to handle. We review the scope and move it to a phase-by-phase quote.