Activated carbon filter

01

Check the compounds, humidity and safety limits

The US EPA's cost manual chapter on carbon adsorbers says they suit dilute VOC streams, below about 100 ppmv, at moderate flow, and when properly designed can remove 95–99% of VOCs at 500–2,000 ppm inlet, and more than 98% for dilute streams. [1]

The same chapter warns that carbon is less effective for highly polar, volatile or small molecules such as vinyl chloride, methanol and formaldehyde, and in humid gas: some studies show about 30% lower removal above 75% relative humidity, and moisture can encourage biological growth. Oxygen-bearing compounds such as peroxides, ketones, organic acids, aldehydes and organic sulfur compounds can react exothermically on carbon and cause bed fires. [1]

EPA describes a particulate filter ahead of the carbon bed in fixed-bed systems, and Clean-Link recommends upstream particulate filtration to protect the carbon media. [1] [2]

Give the supplier the compounds and concentrations, airflow, temperature, relative humidity, dust load, operating hours, outlet limit, space available and how carbon will be replaced or regenerated.

02

Size the bed and plan carbon replacement

EPA explains that bed cross-section follows from the airflow and an empirically chosen superficial velocity: one adsorber vendor uses 85 ft/min, another 65 ft/min, and a carbon maker cautions against exceeding 60 ft/min at one atmosphere. [1]

Editorial calculation: 60 ft/min ≈ 0.30 m/s and 85 ft/min ≈ 0.43 m/s. For 10,000 m³/h, that is 10,000 ÷ 3,600 ≈ 2.78 m³/s, needing about 2.78 ÷ 0.30 ≈ 9.1 m² of bed face at 60 ft/min or 2.78 ÷ 0.43 ≈ 6.5 m² at 85 ft/min. [1] Panel and V-bank filters for HVAC use their own rated face velocities; ask the supplier for them.

For canisters, EPA describes two or more units in series so breakthrough from the first is caught by the second, with sampling between them; the saturated unit is removed and a fresh one added at the clean end. Carbon charge follows from the VOC inlet load, the carbon's working capacity, which is a fraction of its equilibrium capacity, and the time between changes. [1]

The carbon tetrachloride (CTC) figure quoted on media data sheets comes from ASTM D3467, which defines CCl₄ activity as the weight of CCl₄ adsorbed by a carbon sample, as a percentage of the sample's weight, when the carbon is saturated under the method's conditions. ASTM describes it as a measure of the activation level and a quality-control check for gas-phase carbons, and notes that the number does not necessarily show how well the carbon will remove other compounds or perform under other conditions. [3]

Editorial note: use the CTC value to compare carbon grades and check deliveries, but ask the supplier for adsorption or breakthrough data on your own compounds at your humidity and temperature to size the bed and the change interval. [3] [1]

03

Ask for ISO 10121 test data on the media and the complete filter

ISO 10121 sets test methods for gas-phase air cleaning in what it calls "general ventilation". Part 1 (2014) gives a laboratory challenge test for three media configurations: GPACM-LF (loose fill particles), GPACM-FL (flat sheet fabric for flat, pleated or bag devices) and GPACM-TS (three-dimensional structures used as finished elements). Part 2 (2013) tests full-size gas filtration devices (GPACDs) "regardless of media or technique used in the device". Part 3 (2022) classifies GPACDs for single-pass outdoor air using four reference pollutants — ozone, sulphur dioxide, nitrogen dioxide and toluene — at three duty levels each. [4]

Part 1 warns that its elevated challenge concentrations mean test data "should be used to compare GPACM within the same configuration and not for the purpose of predicting performance in a real situation" [4]. That fits the caution this page already gives for the CTC value, which ASTM D3467 treats as a quality index rather than a measure for your compounds [3]. Ask a supplier of pleated or V-bank carbon filters for ISO 10121-2 device data at your airflow, and for media data only within the same configuration.

The classification in Part 3 covers outdoor-air intake filters, not process exhaust; for exhaust adsorbers the EPA cost manual's design guidance on face velocity, humidity and bed sizing remains the reference this page uses [1]. Clean-Link's honeycomb media lists a CTC value of 30–45% and resistance of 250 Pa or less [2]; ask whether those figures come from an ISO 10121 test or the maker's own method.

Editorial calculation: Part 3 sets 4 reference pollutants with 3 duty levels each, 12 pollutant–duty combinations in total; Part 1 defines 3 media configurations. [4]

Values are from the Standard Norge catalogue pages for ISO 10121-1:2014, ISO 10121-2:2013 and ISO 10121-3:2022; the full standards were not reviewed.

04

Compare what suppliers offer

Suppliers linked to this page list activated carbon filters and media for air treatment. [2]

Clean-Link lists carbon media, honeycomb media, pleated panel, pocket, V-bank and compact carbon filters; its honeycomb media lists a carbon tetrachloride adsorption value of 30–45% and filter resistance of 250 Pa or less. Airy Filter lists activated carbon filters alongside panel and paint-booth filters; Compo lists activated carbon air filters and carbon fabric; Koin and Hifine list carbon filters for air purifiers. [2]

05

Trace the filter components

This is a functional reference built from the sources cited; it is not one maker's parts list.

06

Fill the specification fields with values for your exhaust

An activated carbon filter quotation needs values for your gas stream. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.

07

Send the gas, flow and service data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Gas: [compounds; concentrations; outlet limit]
Flow: [m³/h; temperature; relative humidity; dust]
Operation: [hours per day; continuous or intermittent]
Filter: [panel, V-bank, tray box or canister; series stages]
Carbon: [type; mass; CTC or iodine value; impregnation]
Safety: [reactive compounds; temperature monitoring; fire control]
Service: [breakthrough sampling; change interval; disposal or regeneration]

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