What is the FFU (laminar flow hood)?
FFU (Fan Filter Unit) is a combination of fan and filter can also be called
“Motorized HEPA filtration equipment”. FFU are usually installed in the supply
end of the clean room, usually placed on the T-grid with gasket sealed. FFU upper
part is the fan module, the lower part is the filter. Accordance with the
requirements of cleanliness filters for different levels of efficiency (HEPA)
or ultra-efficient (ULPA) filters provide clean air for the clean room. Fan modules
overcome the resistance of the HEPA filter, but also to overcome the resistance
of the whole cycle all channels of wind components in order to maintain the set
running speed. Design and construction of FFU system with simple
characteristics, flexible air flow adjustment, easy to change in the clean
area, so the system has become one of the popular forms of industrial clean
room.
FFU (laminar
flow hood) Features:
1: Flexibility. Because limiting FFU self-powered, it is not limited by region.
In a huge clean room can divided into zoning control according to need.
Moreover, with the change in the semiconductor manufacturing process, plant
layout is bound to be adjusted accordingly, flexibility FFU makes this
adjustment easier, and will not bring secondary investments.
2:
Reusability. If the FFU no need use at moment can be removed, sealed,
safekeeping for next using.
3: Negative
pressure ventilation. This is the unique characteristics of FFU, because of its
own to provide anti-static, making relative to the clean air plenum plant
negative, thus, the particles inside static pressure under pressure will not
leak to clean area, make sealant becomes very simple and safe.
4: Shorten
the construction period. Eliminating the need for the use of FFU duct
fabrication and installation because the air duct in a clean project, takes up
a lot of the construction period , any investor wants to invest as soon as
possible to bring income , the choice of FFU become a possibility .
5: To reduce
operating costs. Although the selection of FFU, the initial investment than
with high ventilation duct, but during running, the outstanding performance of
energy-saving, maintenance-free characteristics, with a 40% reduction in cycle
operating costs.
FFU (laminar flow hood) external residual
pressure (ESP): In
a set speed, the total static pressure FFU (TSP), net of HEPA / ULPA filter
resistance, that is external residual pressure (ESP), the unit is Pa. ESP is
the FFU ability to overcome resistance in the clean room air circulation,
either dimension the overall static TSP FFU and pressure or fan outside the
machine module are required supply airflow volume, or no meaning.
Input energy (input power consumption): normal operation of FFU input voltage and input
current the unit is W. Obviously, FFU that run at different condition of
airflow volume and total static pressure, enter a different energy. Therefore,
if you do not specify the operating point, the value of the input energy does
not make sense.
Unit noise (noise level): according to the standard IES-RP-CC002, the
normal operation of the FFU from the surface of the wind noise level at the
center is 1.2mm below the unit is dB (A). FFU run at different conditions of
airflow volume and total static pressure, different noise. Therefore, if you do
not specify the operating point, the noise level does not make sense.
FFU (laminar
flow hood) fretting (micro vibration): According to
the standard IES-RP-CC002, FFU vibration amplitude and vibration rate at the
maximum operating conditions point unit are mm and mm / s.
Uniformity air velocity (air uniformity): according
to the standard IES-RP-CC002, the normal operation of FFU, the distance by measuring
the surface side of the wind 150mm (6 ") of the horizontal surface wind
speed, the average value of the obtained average wind speed. minimum and
maximum wind speed and air deviation than is uniformity in units of + / - %
standard IES-RP-CC002 FFU required air velocity at any point of its average
wind speed deviation should be within + / - 20% or less .
Air Filter
efficiency (filter grade): according to the European
standard EN1822, HEPA Filter class from H10-H14, U15-U17. Or according to the
American standard MIL-282 (HEPA), for 0.3um efficiency values ; according to
the American standard IES-RP-CC007.1, for 0.12um efficiency values.
