What type of fluid must heat exchangers be provided with an air gap between the walls to prevent toxic transfer?

Heat exchangers need to have an air gap between the walls when dealing with toxic transfer fluids. This is crucial because it prevents any potential transfer of harmful substances from the fluid within the heat exchanger to the surrounding environment or other fluids. The air gap acts as a safeguard, ensuring that any hazardous chemicals or toxins are contained and do not migrate where they could pose a risk to health or safety.

When toxic fluids are involved, they can pose significant health and environmental risks if they leak or are inadvertently mixed with other systems or fluids. The air gap creates a physical barrier that helps mitigate these risks, maintaining both system integrity and safety.

Other types of fluids, such as water, oil, or thermal transfer fluids, do not typically require this level of precaution because they do not carry the same inherent risk of toxicity. While all fluids posed to heat exchangers must be managed carefully, the unique properties and hazards associated with toxic transfer fluids necessitate the additional protective measure of an air gap.