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Article Date: 25th April 2016

EMCEL Filters - Carbon Filters - When Should I Change my Carbon Filter?

Carbon Filters - Activated Carbon Filters - Air Carbon Filtration

EMCEL Filter Unit

As users of Activated Carbon Filters will be aware it is not straightforward to know when your carbon filters are exhausted and require changing. Activated Carbon Filters begin their life with a finite capacity to adsorb Odours, Gases & Vapours and as this capacity is neared the efficiency of the carbon filter begins to decline.

There are several ways to determine when Activated Carbon Filters have reached the point at which change should take place. These include:-

1. The real-time monitoring of the up and downstream air for particular gases to determine the carbon filter efficiency. This method can be expensive and time consuming due to the cost to purchase or hire the necessary instruments and usually requires instruments to be left in place for some days to gain accurate information. It does, however, give precise details of how the filter performs over this given period although it may not be able to predict when filter change is required unless left in place permanently.

2. Instant monitoring of the local area fed by the carbon filtered air to confirm that a desired performance is being achieved. This can be performed using short term gas detection tubes which enable the operator to obtain an instant guide to levels of specific gases. These are however, only a guide to levels of individual gases at the time the monitoring taking place and may not take into account peaks and troughs.

3. Using long term air sampling tubes to collect representative air samples over a typical two week period can be a cost effective method. These are generally low cost and provide an average concentration for selected gases being monitored.

4. Sampling the activated carbon within the filter to establish its remaining capacity to give a very good indication of how much capacity remain within the whole filter. This is usually a laboratory process using a representative sample of used carbon from within the filter. Again this is a very cost effective method to determine actual usage during the filter life and enables the filter user more accurately to determine when the filter efficiency will decline and require replacement.

EMCEL - Carbon CellsIn line with option 4, EMCEL offers a FREE Carbon Life Prediction Service for our carbon cells to ensure our customers maintain the maximum efficiency for their filters and increase economy so cells are not needlessly replaced.


Activated carbon does not change colour during operation and nor is it possible to use pressure loss variation as a guide to usage of a carbon filter.

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