Exhaust Ventilation & LPG Gas Pipeline

Effective LEV or dust/fume extraction can carry away airborne contaminants before they can be breathed in.
local exhaust ventilation(LEV) systemis: an engineering control system to reduce exposures to airborne contaminants such as dust, mist, fume, vapour or gas in the workplace. Simply put it is something that sucks an airborne contaminant out of the workplace
LEV components

LEV systems will have the following components:

1. Hood

The hood captures the contaminated air. To be effective:

• the hood should be positioned as close as possible to the source, or even enclose the source, ideally less than one hood diameter away
• enclose the process as much as possible to avoid draughts that will blow the fumes away from the hood and further into the workplace
• the hood must be the right design for the process and type of contaminant
• the capture velocity must be sufficient to overcome the movement of the contaminant cloud and draw it into the hood
• the worker must not stand between the process and the flow of air to the hood.

2. Ducting

The ducting system carries the contaminated air away from the work area and ideally sharp corners should be avoided in the ducting.

3. Air cleaner

The air cleaner filters and cleans the air before it’s released (outside, away from air intakes).

4. Fan

The fan draws the contaminated air though the hood and ducting to the exhaust stack. The fan must generate sufficient airflow to achieve a capture velocity that draws the contaminant away from the worker’s breathing zone.

5. Exhaust stack

The exhaust stack releases the clean air to the outside.

Types of LEV hoods

One of the common reasons LEV systems are ineffective is because the hood doesn’t capture and contain the contaminated air. There are different designs of LEV hood for different processes.

Enclosing hoods

Enclosing hoods are an effective type of hood because the contaminated air is completely contained. A glove box encloses the process, protecting the operator and preventing the contaminant from entering the workplace. Spray booths enclose the process and the operator. The contaminated air is contained but further controls such as personal protective equipment (PPE) are needed to protect the operator.