Ducted Horizontal Laminar Flow Cabinet

What is the Ducted Horizontal Laminar Flow Cabinet?

A ducted horizontal laminar flow cabinet exhausts its air to atmosphere through a duct after crossing the work surface. It is chosen when exhaust air must leave the room for cleanliness or odour control.

Overview

This model adds a duct connection so that the air leaving the work surface is carried outdoors rather than returned to the room. Supply is still HEPA filtered and flows horizontally at 0.3–0.5 m/s, protecting the work. The exhaust duct must be sized for the cabinet airflow and must not create pressure changes at the cabinet that alter face velocity; a volume control or fan speed adjustment is often used. The cabinet is usually constructed in stainless steel with a smooth interior for cleaning. Because exhaust is removed, the cabinet suits work that generates fine dust, such as powder handling or abrasive operations, and rooms where recirculation is not allowed. An airflow alarm and filter pressure gauge are standard, and the exhaust fan is normally dedicated.

How does it work?

In a horizontal laminar flow cabinet, room air is drawn through a prefilter and a HEPA filter and then pushed through a rear plenum and diffuser. It leaves the back grille as a unidirectional stream at 0.3–0.5 m/s and crosses the entire work surface before reaching the operator, carrying particles and microbes away from the work. Because the stream comes from behind the work, the operator has clear access to the whole bench with no barrier or downward draught. Air may then exhaust to the room or be ducted or recirculated depending on the model. The filter removes at least 99.97 % of 0.3 µm particles for HEPA and 99.999 % for ULPA. Face velocity, filter integrity and particle counts are the performance measures, and the laminar stream is easily disturbed by draughts, so the cabinet must be sited away from doors and air supply diffusers.

What are the key features?

• Ducted exhaust of air after the work surface
• Horizontal HEPA supply at 0.3–0.5 m/s
• Volume control to protect face velocity
• Stainless steel, smooth cleanable interior
• Suitable for dusty or odorous work
• Airflow alarm and filter pressure gauge

What are the technical specifications?

A typical ducted horizontal laminar flow cabinet configuration offers flow direction of Horizontal, rear to front, filter class of HEPA H14, ≥ 99.97 % at 0.3 µm, face velocity of 0.3–0.5 m/s, exhaust of Ducted to atmosphere, duct diameter of 200–300 mm and airflow of 400–1200 m3/h. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Ducted Horizontal Laminar Flow Cabinet is used in powder and fine-dust handling, abrasive or odorous processes, rooms where recirculation is not allowed and cleanroom exhaust applications. Across the wider Horizontal Laminar Flow class, laboratories also deploy it for electronics and optics assembly, media preparation and plating and inspection and packaging.

Which standards and certifications apply?

Relevant standards and methods include ISO 14644-1 (cleanroom classification), ISO 14644-3 (test methods), IEST-RP-CC002 (unidirectional flow clean-air devices), EN 1822 (HEPA and ULPA filters), EU GMP Annex 1 (sterile manufacturing) and GB 50073 (cleanroom design code). Certification candidates for this model are CE and ISO 9001 manufacturing; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Site the cabinet away from doors, windows, air diffusers and walkways, since draughts above 0.2 m/s disturb the horizontal stream. Verify filter integrity and face velocity at installation and at least annually, changing prefilters every 3–6 months. Keep the work area clear of large objects that block the stream, and place items at the sides rather than directly in front of the filter face. Clean the work surface and interior with compatible agents and avoid aerosols that could contaminate the filter. Do not use the cabinet for hazardous aerosols or chemical vapour, since it protects only the work. Record requalification results to support audits.

How do I select the right Ducted Horizontal Laminar Flow Cabinet?

Choose the ducted model when exhaust must leave the room, for example with fine dust or where recirculation is prohibited. Confirm duct sizing and that exhaust changes do not affect face velocity. RFQ: airflow, duct route and diameter, fan details and width.

How does it compare with other Horizontal Laminar Flow variants?

Choose a horizontal laminar flow cabinet when the task needs clear, unobstructed access to the work surface and the operator does not need protection from aerosols. Decide whether the cabinet recirculates, exhausts to the room or is ducted, based on room conditions and the process. Select filter class by the required cleanliness, commonly HEPA H14 for ISO 5 and ULPA for ISO 4 or better, and match width and working height to the equipment. For GMP or aseptic use, choose stainless steel construction with cleanable surfaces. Confirm face velocity, filter integrity and particle counts at commissioning, and check that the site has no strong draughts. Horizontal flow is less suitable for tall work or when the operator must lean over the work, since the air then travels towards the operator's breathing zone.