Activated Carbon Ductless Fume Hood

What is the Activated Carbon Ductless Fume Hood?

An activated carbon ductless hood filters organic vapours through carbon adsorption beds before recirculating air into the room. It suits low-volume solvent handling in teaching and small laboratories where ducting is impractical.

Overview

The hood contains a prefilter and one or two carbon filter beds containing 5–20 kg of granular activated carbon, with bed depth of 25–50 mm. Adsorption capacity depends on the solvent, typically 10–40 % by weight. Airflow is 300–800 m3/h, giving face velocity of 0.4–0.5 m/s. The body is polypropylene or epoxy-coated steel, with LED lighting, a control panel and airflow alarm. Gas sensors can monitor outlet concentrations and signal breakthrough. Filters are top or rear loaded. The hood is suitable for alcohols, ketones, esters and hydrocarbons in low quantities, but some small molecules, such as methanol or formaldehyde, are adsorbed poorly by plain carbon. The design avoids ducting costs and gives flexibility to locate the hood.

How does it work?

A ductless fume hood uses a fan to pull room air through the sash opening at 0.4–0.5 m/s across the work area, then through one or more filter stages before discharge back into the room. A prefilter removes dust, and activated carbon beds adsorb organic vapours through physical adsorption. Chemically impregnated carbon or specialist media can capture acids, ammonia or formaldehyde. A HEPA stage can be added for particles. Sensors or timers indicate filter saturation, and airflow monitors ensure correct face velocity. Because filters have finite capacity, the hood is limited to known chemicals in limited quantities, and filter selection must match the vapour. The body is typically polypropylene or epoxy-coated steel, with lighting and a control panel.

What are the key features?

• Prefilter plus 1–2 activated carbon beds
• 5–20 kg carbon with 25–50 mm bed depth
• Airflow 300–800 m3/h at 0.4–0.5 m/s
• Optional gas sensor for breakthrough
• Polypropylene or epoxy steel body
• Top or rear filter loading

What are the technical specifications?

A typical activated carbon ductless fume hood configuration offers filter media of Granular activated carbon, carbon mass of 5–20 kg, bed depth of 25–50 mm, airflow of 300–800 m3/h, face velocity of 0.4–0.5 m/s and width of 600–1500 mm. 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 Activated Carbon Ductless Fume Hood is used in teaching laboratories, solvent handling in QC, pharmacy compounding and art and conservation. Across the wider Ductless Fume Hoods class, laboratories also deploy it for teaching laboratories, quality control and pharmacies.

Which standards and certifications apply?

Relevant standards and methods include ASHRAE 110 (testing performance of laboratory fume hoods), AFNOR NF X 15-211 (ductless fume cupboards), ISO 14644-1, EN 14175-1 (fume cupboards, vocabulary), GB/T 34269 and IEC 61010-1. 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.

Establish a chemical register before purchase and have the supplier confirm filter compatibility in writing. Change filters at the recommended interval or sooner if gas sensors or odour indicate breakthrough, because carbon saturation is sudden at the end of life. Test airflow and filter seals on installation and at least every 6–12 months, keeping records for audit. Place the hood away from doors and air currents, and with clearance to allow filter replacement. Dispose of used filters as hazardous waste. Train users to restrict quantities, keep sashes low and never use the hood for chemicals outside the compatibility list.

How do I select the right Activated Carbon Ductless Fume Hood?

Choose activated carbon for organic solvents in low quantities. Use impregnated media for acids and ammonia, and a ducted hood for unknown or highly toxic substances. RFQ: chemical list, daily quantities, working hours and filter monitoring requirements.

How does it compare with other Ductless Fume Hoods variants?

Select by the chemicals used. Every application needs a chemical compatibility assessment from the supplier to match filter media, and the assessment should include quantities, frequency and breakthrough behaviour. Choose an activated carbon filter for organic solvents, impregnated carbon for acids or amines, and HEPA for particulates. Consider filter monitoring, such as gas sensors that signal breakthrough, rather than timers alone. Choose width, typically 600–1500 mm, noise level, and whether a base cabinet for storage is required. Ductless hoods are not suitable for unknown, high-volume or highly toxic chemicals, or for heated perchloric acid. Confirm local regulations on recirculating air, since some jurisdictions restrict their use.