Which source shall NOT be used to power the venturi of a WAGD system?

The correct choice regarding which source should not be used to power the venturi of a Waste Anesthetic Gas Disposal (WAGD) system is medical air.

In a WAGD system, the venturi effect relies on specific gas characteristics to function effectively. Medical air is primarily composed of nitrogen and oxygen, but it does not have the optimal properties required to create a proper vacuum for anesthetic gases. Unlike other gases that can hold specific properties beneficial for the venturi mechanism, medical air lacks the necessary pressure differentials and flow consistency needed to effectively maximize the evacuation of waste anesthetic gases.

In contrast, other gases like oxygen, nitrous oxide, and carbon dioxide can be used in specific contexts. For example, oxygen may be involved for its high density and efficiency in creating the required flow, while nitrous oxide and carbon dioxide can help initiate movement through their specific properties. Thus, medical air is considered unsuitable for this application within the context of WAGD systems.