Here’s a brief overview of each type of damper and the ceiling diffuser you mentioned:

• 1. Round Fire Damper:
  – Purpose: Designed to prevent the spread of fire through ductwork by automatically closing when exposed to high temperatures.
  – Application: Typically installed where ductwork penetrates a fire-rated wall or floor.
  – Mechanism: Often features a fusible link that melts in high heat, causing the damper to close.

2. Round Backdraft Damper:
– Purpose: Prevents air from flowing backward through the ductwork.
– Application: Commonly used in ventilation systems to ensure air flows in one direction only.
– Mechanism: Usually consists of a spring-loaded flap that closes when there is reverse airflow.

3. Round Damper:
– Purpose: Used to control the airflow within the ductwork.
– Application: Can be manually or automatically adjusted to regulate the volume of air passing through a duct.
– Mechanism: Comes in various designs, including manual lever-operated dampers or motorized dampers.

4. Round Duct Damper:
– Purpose: Similar to the round damper, it controls airflow but specifically designed for round ducts.
– Application: Used in HVAC systems to balance and control airflow in round duct installations.
– Mechanism: Available in manual or automatic versions.

5. 6 Inch Round Ceiling Diffuser with Damper:
– Purpose: Distributes air evenly into a room and allows for control of airflow volume.
– Application: Installed in ceilings, typically in residential or commercial HVAC systems.
– Mechanism: Combines a diffuser (to spread air) with an integrated damper (to control airflow), often adjustable via a dial or lever.

These components are essential in HVAC systems for ensuring proper ventilation, temperature control, and safety. If you need more specific information or recommendations, please let me know!