During asbestos removal, negative pressure is used to control the airflow within the enclosed work area. By creating lower air pressure inside the work area, the air is directed toward the work area rather than out into the surrounding spaces. This reduces the risk of asbestos fibers spreading outside the enclosure during the work.
Why is negative pressure used during asbestos removal?
When materials containing asbestos are demolished or processed, fibers can be released and become airborne. During indoor remediation, the work area must therefore normally be isolated from the rest of the building.
The negative pressure works in conjunction with the enclosure to create a directed airflow. For example, if there are minor leaks in the enclosure, air will be drawn into the remediation zone instead of contaminated air leaking out.
An airlock is used for entry and exit, while the airflow in the decontamination area is controlled by the negative pressure system.
How is the negative pressure created in the decontamination zone?
The negative pressure is created by a fan unit that continuously extracts air from the enclosed area. As air is removed from the remediation zone, it is replaced by air coming in from outside, which creates the pressure difference and the desired airflow.
The air that is extracted must be filtered before it leaves the remediation area. For this reason, units equipped with HEPA filters are used to remove small particles and fibers from the airflow.
The placement of the equipment and the way air is supplied to the remediation zone also affect how the air moves through the area.
Air circulation needs to be adjusted to the space
The size of the decontamination zone affects the capacity required. The Swedish Work Environment Authority specifies that the air inside the containment area must be replaced at least ten times per hour during work.
A remediation area with a volume of 100 m³ therefore requires an air exchange rate of at least 1,000 m³ per hour. In larger remediation zones, higher capacity or multiple units may therefore be required to achieve sufficient air exchange.
It is therefore not enough to simply create a vacuum. The equipment must be sized according to the specific remediation area.
The negative pressure must be maintained during the work
The negative pressure must remain in effect while remediation work is underway. Changes to the containment system, openings, and air pathways can affect airflow and must therefore be managed so that the remediation zone remains isolated from the surrounding area.
Once demolition is complete, the fan units are also used for post-demolition ventilation. The decontamination area is cleaned, and air continues to be circulated until the containment and airlock are removed.
Negative Pressure Equipment for Asbestos Removal
At Alron, you’ll find equipment and accessories for professional asbestos removal, including products for containment, filtration, and management of the removal site.
Do you need help finding the right equipment for your remediation project? Contact us at Alron, and we'll help you find products based on the specifics of your project.
