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  2. Ductwork airtightness - Wikipedia

    en.wikipedia.org/wiki/Ductwork_airtightness

    There are two major systems to classify ductwork airtightness, one based on European standards, the other based on ASHRAE standard 90.1-2010.Both are based on the leakage airflow rate at a given ductwork pressure divided by the product of the ductwork surface area and the same ductwork pressure raised to the power 0.65.

  3. Duct (flow) - Wikipedia

    en.wikipedia.org/wiki/Duct_(flow)

    Some flexible duct markets prefer to avoid using flexible duct on the return air portions of HVAC systems, however flexible duct can tolerate moderate negative pressures. The UL181 test requires a negative pressure of 200 Pa. To use flexible ducting in a system, make sure to pull the duct tight so you get the full internal diameter.

  4. Fanno flow - Wikipedia

    en.wikipedia.org/wiki/Fanno_flow

    The viscous friction causes the flow properties to change along the duct. The frictional effect is modeled as a shear stress at the wall acting on the fluid with uniform properties over any cross section of the duct. For a flow with an upstream Mach number greater than 1.0 in a sufficiently long duct, deceleration occurs and the flow can become ...

  5. Duct leakage testing - Wikipedia

    en.wikipedia.org/wiki/Duct_leakage_testing

    Duct leakage test in the US. A duct leakage tester is a diagnostic tool designed to measure the airtightness of forced air heating, ventilating and air-conditioning (HVAC) ductwork. A duct leakage tester consists of a calibrated fan for measuring an air flow rate and a pressure sensing device to measure the pressure created by the fan flow.

  6. Pressurisation ductwork - Wikipedia

    en.wikipedia.org/wiki/Pressurisation_ductwork

    Pressurisation ductwork is a passive fire protection system. It is used to supply fresh air to any area of refuge , designated emergency evacuation or egress route. Purpose

  7. Process duct work - Wikipedia

    en.wikipedia.org/wiki/Process_Duct_Work

    This suction pressure operates to cause suction pressure collapse on the duct side walls. Also this pressure operates perpendicular to the duct "expansion joints" to create an additional load on the duct supports that adds to dead, and live loads. Please note: duct pressure loads vary with temperature, as the gas density varies with temperature.