© 2022 VAF Air Ltd
VAF Air Ltd

How to Calculate a confined space

VAF Air recommends that you change the air in a confined space at least 20 times each hour, or once every 3 minutes. Where possible we would always recommend that you not only extract the air but also utilize a blower to push clean air into the workspace. The Miniveyor Air VAF fans work on both positive and negative air flow, so are equally at home extracting as well as blowing. To use this recommended method, you would need 2 or more openings to your confined workspace and employ 2 fans. If you only have 1 opening, then you should use positive airflow and use the fan to blow air into the confined workspace. To determine which of our exhaust blowers is suitable for your application you must first calculate the volume of your confined workspace. If the space is a regular shape (cube or rectangle) then you would simply multiply the length by the width, and then finally by the height. It is important that you use the same unit of measurement as used to rate the fan. You should use either feet or meters as our blowers are rated in either cubic feet per minute (CFM) or cubic meters per hour (m³/hour). If the workspace is not rectangular or cube, simply divide the space into smaller rectangular spaces to help you calculate the volume. For cylindrical spaces, such as tanks, pipes or silos calculate the volume using Pi (3.142) x the radius squared x the length.

CFM Example (Imperial units)

m³/hour Example (Metric units)

Blower Selection

© 2022 VAF Air Ltd
VAF Air Ltd

Blower Selection

How to Calculate a confined space

VAF Air recommends that you change the air in a confined space at least 20 times each hour, or once every 3 minutes. Where possible we would always recommend that you not only extract the air but also utilize a blower to push clean air into the workspace. The Miniveyor Air VAF fans work on both positive and negative air flow, so are equally at home extracting as well as blowing. To use this recommended method, you would need 2 or more openings to your confined workspace and employ 2 fans. If you only have 1 opening, then you should use positive airflow and use the fan to blow air into the confined workspace. To determine which of our exhaust blowers is suitable for your application you must first calculate the volume of your confined workspace. If the space is a regular shape (cube or rectangle) then you would simply multiply the length by the width, and then finally by the height. It is important that you use the same unit of measurement as used to rate the fan. You should use either feet or meters as our blowers are rated in either cubic feet per minute (CFM) or cubic meters per hour (m³/hour). If the workspace is not rectangular or cube, simply divide the space into smaller rectangular spaces to help you calculate the volume. For cylindrical spaces, such as tanks, pipes or silos calculate the volume using Pi (3.142) x the radius squared x the length.

CFM Example (Imperial units)

m³/hour Example (Metric units)

© 2022 VAF Air Ltd
VAF Air Ltd

Blower Selection

How to Calculate a confined space

VAF Air recommends that you change the air in a confined space at least 20 times each hour, or once every 3 minutes. Where possible we would always recommend that you not only extract the air but also utilize a blower to push clean air into the workspace. The Miniveyor Air VAF fans work on both positive and negative air flow, so are equally at home extracting as well as blowing. To use this recommended method, you would need 2 or more openings to your confined workspace and employ 2 fans. If you only have 1 opening, then you should use positive airflow and use the fan to blow air into the confined workspace. To determine which of our exhaust blowers is suitable for your application you must first calculate the volume of your confined workspace. If the space is a regular shape (cube or rectangle) then you would simply multiply the length by the width, and then finally by the height. It is important that you use the same unit of measurement as used to rate the fan. You should use either feet or meters as our blowers are rated in either cubic feet per minute (CFM) or cubic meters per hour (m³/hour). If the workspace is not rectangular or cube, simply divide the space into smaller rectangular spaces to help you calculate the volume. For cylindrical spaces, such as tanks, pipes or silos calculate the volume using Pi (3.142) x the radius squared x the length.

CFM Example (Imperial units)

m³/hour Example (Metric units)