An airtight isolation damper needs a defined leakage requirement at stated pressure conditions. The word “airtight” does not describe the test basis, casing leakage, actuator behaviour or the condition of the installed duct joints.
Separate the boundaries
Closed-blade leakage concerns flow past the shut damper. Casing leakage concerns air crossing the housing to its surroundings. The duct connections create additional installation boundaries. Specify the relevant requirement for each rather than treating one test result as proof of the whole system.
Identify pressure direction, normal duty and any isolation or decontamination conditions. Materials and seals must be compatible with the actual medium and environment. A general ventilation damper should not be assumed suitable for a specialist containment duty.
Write the control states
Define open, closed, commanded movement, loss of power or air supply, and fault indication. Electric and pneumatic actuators have different service needs. A position switch reports its designed condition; it should not automatically be described as proof of leakage performance.
Coordinate the damper with fans, access doors and any other interlocks in the approved system sequence. The safe failure position depends on the application and should be established by the responsible designer rather than chosen as a universal default.
Plan access for the seal and actuator
Leave space to inspect the blade sealing surfaces, replace actuators and reach connection hardware. A damper installed against a wall or above inaccessible equipment can become difficult to verify or maintain. Identify the access side on the duct drawing.
Halton's gastight shut-off damper information separates closed-blade leakage from casing performance. Obtain the corresponding evidence for the offered isolation damper at the required pressure and direction; the surrounding AHU's classification is not a substitute.
shengtongJH can coordinate airtight damper configurations and actuator interfaces against a defined specification. Send pressure duty, leakage requirements and the control sequence to establish the appropriate supply and verification scope.