To determine whether the high efficiency filter itself and its installation has obvious leakage, the following must be tested in the field: filter media; filter media and its framework within the connection; filter frame gasket and filter Between the support frame and the wall or ceiling. DOP leak detection materials, equipment: dust source (PAO solvent), aerosol generator, aerosol photometer. The aerosol generator is ATITDA-6C, a hand-held Laskin nozzle aerosol generator that uses air directly without the need for compressed air as power. At a working pressure of 20 Pa, the gas flow velocity of 50 ~ 2025f3 / min, can produce 10 ~ 100ug / mL concentration of polydisperse submicron oil dust aerosol. The aerosol photometer used was an ATI2H photometer with a dynamic measurement range of 0.00005 to 120 ug / L and a sampling flow rate of 1F3 / min (28.3 L / min).
In this case,
3.1 Introduction of PAO aerosol on the upstream side of HEPA to be tested For HEPA in HVAC system, the aerosol can be introduced directly from the negative side of the system fan in order to make the concentration of aerosol reach HEPA uniform. , It should be introduced at least 10 times the diameter of the HEPA duct and minimize turning. Under normal circumstances, to maintain the required concentration of aerosol upstream, and the concentration fluctuations in a certain range. For laminar flow hoods, HEPA on clean benches, aerosols are introduced directly from the negative side of the system fan.
In this case,
3.2 Aerosol photometer initialization, set 100%, 0% reference standard value in accordance with aerosol photometer operation requirements for initialization, set the alarm value. Connect the UPSTREAM sampling tube to the upstream sampling port to measure the concentration of aerosol upstream. According to aerosol generator operating requirements to adjust the aerosol concentration occurs, so that the upstream aerosol concentration of 10 ~ 20ug / mL
