How to Set Fire Dampers Optimally in HVAC Systems?

Proceeding from the code, GB 15930 - 2007 "Fire Dampers for Building Ventilation and Smoke Exhaust Systems" only specifies three types of dampers: fire dampers (FHF), smoke fire dampers (PFHF), and smoke dampers (PYF).
From the definitions, it can be seen that fire dampers (FHF) are normally open at 70 °C, smoke fire dampers are normally open at 280 °C, and smoke dampers (equivalent to smoke outlets here) are normally closed.

Question 1: Does a fire damper that is normally closed at 70 °C exist?
There should be a DFHF (B 70 °C), that is, a normally - closed electrically - controlled fire damper at 70 °C. It is normally closed at ordinary times, can be opened electrically, and reset manually or electrically. It closes when the fuse melts at 70 °C, and is applied to gas - fire - fighting rooms that do not require exhaust ventilation at ordinary times (such as air - conditioned archives).

Question 2: Does a smoke fire damper that is normally closed at 280 °C exist?
There is an "automatic smoke fire damper" that is normally closed at ordinary times and opens in case of a fire. This is similar to the action of a smoke damper, but a smoke damper generally does not have the fire - prevention function of melting at 280 °C, while the automatic smoke fire damper can close when it melts at 280 °C. This damper should be installed on the pipeline of the smoke exhaust system or at the suction inlet of the smoke exhaust fan.
The "automatic smoke fire damper" here can be replaced by a normally - closed smoke damper/smoke outlet + a normally - open 280 °C smoke fire damper. In case of a fire, the smoke outlet opens and the fan starts in a linked manner. If it is installed at the suction inlet of the fan and the end of the smoke exhaust pipeline, in case of a fire, all the "automatic smoke fire dampers" need to be started in a linked manner, and the fan also needs to be started in a linked manner. The control is more complex. If one of them fails to open, the system cannot operate normally, and its reliability is not as good as that of a normally - closed smoke damper/smoke outlet + a normally - open 280 °C smoke fire damper.

Question 3: Does a normally - open smoke damper exist?
The smoke damper here is equivalent to a smoke outlet. For common plate - type smoke outlets and multi - blade smoke outlets, the common types in the market are normally - closed. Generally, a normally - open smoke outlet is not required. For the smoke outlet of an exhaust - and - smoke - exhaust combined system, it can be controlled by a "single - layer louver + 280 °C electrically - controlled smoke fire damper".

Question 4: What are the application scenarios of 70 °C fire dampers?
Fire dampers have many application scenarios. They need to be installed in the main ducts of air - conditioning supply and return air, at the inlets and outlets of ventilation fans, at the entrances of air shafts, where the pipeline passes through fire compartments/deformation joints/important rooms/machine rooms/partitions or floors of rooms with high fire risks, and at the connections between vertical air ducts and horizontal air ducts on each floor. And in many other scenarios, fire dampers are required.

Question 5: Does the fresh air intake duct of an air - conditioner need to install a fire damper?
Generally, it is not necessary. Especially if fire dampers are installed in both the return air and supply air, there is no need to install a fire damper at the fresh air intake. And generally, the intake is located outdoors, and according to the code requirements, it should maintain a horizontal distance of more than 10 m or a vertical distance of more than 3 m (with the smoke outlet above) from the smoke outlet. Generally, smoke will not enter the air - conditioner from the fresh air intake, so a fire damper is generally not required.

Question 6: When an air - conditioner air duct is connected to an air shaft, if it does not pass through a fire compartment and the air shaft only has this one air duct, does it need to install a fire damper?
When an air - conditioner air duct is connected to an air shaft, if it does not pass through a fire compartment and the air shaft has two or more air ducts (i.e., multiple systems share the air shaft), a normally - open 70 °C fire damper needs to be installed at the connection of the air duct to the air shaft, and a check valve should be installed after the fire damper. If the air duct passes through a fire compartment, a fire damper must be installed.

Question 7: On which side should the fire damper be installed?
The fire damper should be installed on the same side as the air - flow direction. That is, if it is a supply air duct, the fire damper should be installed on the side that has not passed through the wall. Fire dampers should be installed on both sides of the deformation joint.

If there is no space or it is not convenient to install on one side where the fire damper needs to be installed, it can be changed to the other side according to the construction requirements.

Question 8: If the fan outlet directly opens a louver to the outdoors, does a fire damper need to be installed on the fan outlet side?
For a fan in a fan room, if the outlet directly opens a louver to the outdoors, a fire damper may not be installed at the fan outlet. Of course, it is okay to install a normally - open 70 °C fire damper and link it with the fan. However, at this time, only when the fan room catches fire and the air duct is burned through will this valve take effect. And since the fan outlet directly leads to the outdoors through the louver, the function of this valve is basically limited.
If the pipeline at the fan outlet needs to pass through important rooms/rooms prone to catching fire/fire compartments, etc., before leading to the outdoors, a 70 °C fire damper also needs to be installed on the outlet side of the exhaust fan in the fan room.