Get Better Pricing with Red Check Advantage.
New Products in Fall Protection available now.

Confined Space Ventilation Basics

You must ask yourself several questions before tackling a confined space application. Where will the blower be used? Is it hazardous or nonhazardous? How many times should the air in a confined space be circulated per hour? The majority of confined space ventilation issues can be prevented with education and the use of proper equipment.


Picking the Best Fan or Blower for the Job

When selecting a fan or blower, all ventilators have two characteristics:

  1. Air pressure - Force of air volume is measured by inch of water gauge (WG)
  2. Air flow - Air volume delivered and measured by cubic feet per minute (CFW)


Axial Fans:

Create high air flow but the blade design develops lower pressure. When used with ducting, the ventilation duct creates air movement resistance. therefore making the axial fan become inefficient at longer distances. Axial fans are designed with several large paddle blades that develop a large volume of air flow (CFM).

When to use Axial Fans:

They are lightweight, low cost and best when working at short distances with minimal ducting (preferably 15 to 25 ft flexible ducting).


Centrifugal Blowers:

Uses a "squirrel cage" designed with numerous forward curving blades on a circular wheel. The blades create significant volume (CFM) and very high air pressure (WG).

When to use Centrifugal Blowers:

They are typically heavier and cost more than axial fans due to the motor required to efficiently run the blades. These blowers are used to move air a long distance, using long or multiple lengths of duct.


In-Line Axial Fans:

Used by itself or used with a fan/blower as a velocity accelerator for long duct distances over the 15 to 25 foot standard duct length.

When to use:

When ventilating at a long distance, simple add an in-line fan to the ducting to increase or maintain air flow. In-line fans can be used with either axial or centrifugal blowers to extend longer ventilation distance.


Venturi Air Blower

Operates with a pneumatic air hose and uses no moving parts or blades. Tremendous CFM is created by using a hollow hub that spins air similar to a jet engine.

When to use:

With no mechanical blade, the Venturi is not specifically designed to force air through flexible ducting. The Venturi is primarily used as a suction or push device used on a tank and can be used in conjunction with an axial or centrifugal fan to rapidly remove gases from a tank. Venturi bases are designed to fit American Petroleum Institute (API) standard tanks.


Pneumatic Circular Jet Fan

Operates with a pneumatic air hose to ventilate tanks

When to use:

This fan is designed to push air in or remove air from tanks to assist Venturi blowers in rapidly removing gases from the tank. The jet fan bases are designed to fit American Petroleum Institute (API) standard tanks.


Custom Centrifugal Blowers

Designed for high air pressure (WG) and high air flow (CFM) measuring thousands of CFM. Large blowers allow ventilation to flow over long distances and establish air manifolds for multiple ventilation at remote areas. A high pressure portable blower can deliver positive or negative air flow while removing dust and/or gases for long distances.

When to use:

Custom blowers for special applications to properly ventilate the work situation.


Reach out to us - - if you need more information or help on finding your ideal Confined Space Entry Ventilation System!


This content was provided in partnership with Air Systems International For the original document please reference: Confined Space Ventilation


AIR Systems logo

Back to Blog

Related Articles

Portable Gas Detectors Help Mitigate Risks in Confined Space

A hazardous atmosphere inside of a confined space is one of the most dangerous, yet frequently...

Fall Protection Requirements for Confined Space Work

Confined spaces present health and safety risks for many workers. This is why recognizing and...

Confined Space in The Brewery Industry

Confined spaces are some of the most dangerous and potentially life-threatening work environments...