1. Product technical requirements
1.1 General
The unit structure must be sealed; leakage at internal static pressure 600 Pa must be ≤1%. The frame is square-steel; thickness not less than 1 mm. It must resist wear, heat and corrosion, and be strong enough to avoid permanent deformation in transport and operation. The project runs 24 hours a day and the frame must hold for 10 years.
1.2 Panels
Panels are polyurethane foam, with galvanised steel inner skin, both 0.50 mm thick; thermal bridging is broken on both faces of the frame. A flame-retardant insulation sits between the two skins; its thermal conductivity must not exceed 0.035 W/m·°C and the outer surface must not sweat. Insulation thickness ≥50 mm. Panels are removable and reassembled on site, fixed to the frame by screws. The base has enough strength and stiffness for a person to enter without deformation or damage.
1.3 Primary filter (G4)
Use a known brand. The filter has an integral frame, front-loaded. Quick-release fittings mount it on a sealed movable frame so unfiltered air cannot bypass. Plate-type, washable, non-woven media. It must run to 600 Pa without damage. A local differential-pressure gauge is fitted.
1.4 Secondary filter (F6)
Known brand, integral front-loaded frame, quick-release on a sealed movable frame. Bag-type, washable, non-woven media. Runs to 600 Pa without damage. Local differential-pressure gauge fitted.
1.5 Fan section
Known-brand external-rotor fan, low noise. Impeller of high-strength steel or fully welded aluminium; shaft of hard steel; imported sealed self-aligning bearings rated 20,000 hours. The drive sits on a vibration-isolating frame. All metal surfaces in the airstream are rust-proofed.
1.6 Cooling/heating coil
Copper tube with aluminium fins; fins even and flat, mechanically fixed. The coil panel is removable to pull the coil out for service. Copper tube outer diameter φ16, wall ≥0.5 mm; fin minimum thickness 0.2 mm (hydrophilic film). Coil frame is stainless steel. Supply/return, drain and vent are on the same side. All pipe penetrations use mechanical sleeves with insulated packing. External pipes have bolted flanges. Air and water cross-flow. Coil pressure-tested at 1.6 MPa. Drain and vent plugs provided. The stainless steel condensate pan slopes down and exits below, keeping drainage clear with no pooling. All coils are firmly fixed.
1.7 Other
Fit a waterproof light and an access door on the relevant sections.
Exhaust fan cabinet requirements
Product technical requirements. Installation follows site conditions.
1. General
The unit must be sealed; leakage at internal static pressure 500 Pa must be ≤1%. Square-steel frame, thickness ≥1 mm, wear/heat/corrosion resistant, strong enough for 24-hour operation and 10 years without deformation.
2. Panels
Polyurethane foam with 0.50 mm galvanised steel inner skin, screwed to the frame. The base has enough strength and stiffness for a person to enter without damage.
3. Fan
Known-brand external-rotor fan, low noise. Impeller of high-strength steel or fully welded aluminium; hard-steel shaft; imported sealed self-aligning bearings rated 20,000 hours. Drive on a vibration-isolating frame; airstream metal surfaces rust-proofed.