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Ventilation

One of the primary hazards of working in a confined space is the lack of breathable air. Since by definition a confined space has limited means of entry or exit, the forces of natural ventilation are all but nonexistent. Consequently, the air may become contaminated by any number of gases or chemicals. Most commonly these are Carbon Monoxide (CO) from incomplete combustion, Hydrogen Sulfide (H2S) a heavier than air gas produced from decaying organic compounds, and Explosive Gases such as Methane.

One of the many standard procedures when preparing to enter and occupy a confined space is to check for the gases with a Confined Space Gas Detector. Whether or not the readings come back clean, the work being performed within the tank, vault or pit may generate gases (welding for instance), or may disturb the contents in such a way as to release previously trapped gases. The answer is both continuous and effective ventilation.

Mechanical ventilation, such as is provided by a fan and ducting, must supply sufficient volume to replace contaminated air with clean, breathable air. This may seem straightforward, but experienced rescuers will tell you that this is not always the case. The volume, shape and depth of the confined space may present obstacles to getting a complete purge.

Supply ventilation, or pushing air into the space, is generally felt to be the most effective method. The contaminated air will exit by the least restrictive path. This must be taken into consideration, and it goes without question that every situation will present it's own unique challenges. The so-called 'Nomograph' located below is used to obtain a rough estimate of the amount of time it takes a given fan (capacity) to change the air in a given space (volume). We say estimate, because a deep space with heavier than air contaminants (for instance), may take more volume to clear than a shallow tank with multiple openings.

We generally recommend electrically powered fans for confined space work. There are gasoline powered fans available, but the possibility of introducing carbon monoxide from the exhaust has caused us to shy away from these. Air powered ventilation devices, sometimes called air ejectors are another. These are noisy, but have the advantage of no moving parts, and with proper grounding may be useful in explosive atmospheres.

Speaking of explosive atmospheres...If your confined space gas detector indicates that your proposed work area contains methane or another combustible gas, you may want to consider choosing a hazardous location fan. These devices have specially constructed motors, and conductive ducting, to insure that dangerous sparks or static electricity won't set off an explosion. Our Euramco RamFan Hazardous Location blowers are ATEX rated. Getting approved is rigorous, and recognized as the global standard when referring to this type of blower.

Using the air movement volume figures shown with each fan or blower assembly, refer to the nomograph below to estimate the amount of time needed to purge your confined space. You may note from the chart that Allegro recommends changing the air 20 times per hour (once every 3 minutes). Using any particular figure out of context is a little controversial. Rescue professionals with years of experience argue this point. Your training and company rules (if applicable) are the best guidelines.

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  1. BW GasAlert MAX XT II CS Kit With Ventilation XT-CS-9533-25
    BW GasAlert MAX XTII CS Kit With Ventilation XT-CS-9533-25
    Regular Price $1,830.15 Sale Price $1,416.15 You Save $414.00
    - Usually ships in 5 - 7 days
  2. Pelsue 1/3 HP Axial Blower 1325D
    Pelsue 1/3 HP Axial Blower 1325D
    $559.00
    - Usually ships next business day
  3. Euramco RamFan UB20 Blower and Duct/Canister 15 and 25 FT Available
    RamFan UB20 Blower, Duct and Canister 15 and 25 ft.
    $609.00
    - Usually ships in 2 - 3 days
  4. Ecko K2025 Blower
    ECKO Confined Space Blower, Ducting and Canister K2025
    Rating:
    100%
    $358.00
    - Usually ships in 2 - 3 weeks
  5. Euramco RamFan UB20 Saddle Vent System
    RamFan UB20 Saddle Vent System
    $930.00
    - Usually ships in 2 - 3 days
  6. ECKO K20 8 in. Confined Space Ventilation Blower
    ECKO K20 8 in. Confined Space Ventilation Blower
    $219.00
    - Usually ships in 2 - 3 weeks
  7. Allegro 12 in. Axial Blower with Canister and Ducting
    Allegro 12 in Axial Blower with Canister and Ducting 9543
    $608.00
    - Usually ships in 2 - 3 days
  8. Euramco RamFan UB20XX Blower Duct/Canister
    RamFan UB20XX Blower, Ducting and Canister
    $2,186.00
    - Usually ships in 5 - 7 days
  9. Euramco Ramfan EFC50 16" Smoke Ejector
    RamFan 16 in. Smoke Ejector EFC50
    $1,585.00
    - Usually ships in 1 - 2 weeks
  10. Euramco ECKO-FLEX 12 in. x 10 m Flexible Ducting
    Euramco ECKO-FLEX 12 in. x 10 m Flexible Ducting
    - Usually ships in 2 - 3 days
  11. Allegro 16 in. Duct
    Allegro 16 in. Confined Space Industrial Ducting
    $285.00
    - Usually ships in 3 - 4 days
  12. Euramco RamFan UB30 Blower/Ventilator
    RamFan UB30 Confined Space Blower and Exhauster
    $377.00
    - Usually ships in 5 - 7 days
  13. Allegro 8 Inch Axial Blower with Canister and Hose 9514
    Allegro 8 In. Axial Blower with Canister and Hose
    $592.85
    - Usually ships in 2 - 3 days
  14. Allego Plastic Venturi Blowers
    Allegro Industries Plastic Venturi Blowers 9518
    $200.00
    - Usually ships in 2 - 3 days
  15. Euramco RamFan UB20 Battery Pack System
    RamFan UB20 Battery Pack System
    $1,613.00
    - Usually ships in 1 - 2 weeks
  16. Euramco RamFan Intrinsically Safe 12 in. Blower EB7201XX
    RamFan Intrinsically Safe 12 in. Blower EB7201XX
    $2,172.00
    - Usually ships in 1 - 2 weeks
  17. Allegro 16 in. Standard Confined Space Blower/Ventilator 9515
    Allegro 16 in. Standard Confined Space Ventilation Blower 9515
    $864.29
    - Usually ships in 3 - 4 days
  18. Euramco Safety Duct Coupler Stainless
    Euramco Safety Duct Coupler Stainless HD
    $37.00
    - Usually ships in 2 - 3 days
  19. 12" Allegro Plastic Ducting Storage Canister
    Allegro 12 in. Plastic Ducting Storage Canister 9550-55
    $115.72
    - Usually ships in 2 - 3 days
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