DESOTEC’s new product developments

DESOTEC is committed to finding solutions to our clients’ filtration requirements. To supplement our core provision of activated carbon filters, our technical team develops products that address particular issues raised by clients.

In the past few years, we have mainly focused on two areas: safety, and emission monitoring. Three products are now in widespread use in our projects: the INERTI-BOX, the HC-BOX, and the VOC-BOX.

Safety: the INERTI-BOX and the HC-BOX

DESOTEC filters are very safe, particularly as we handle all spent carbon away from clients’ sites. However, for some air emission (and potentially biogas) applications there is an increased risk that hotspots could develop.

These are formed when high concentrations of certain molecules, such as aldehydes and ketones, are adsorbed onto activated carbon, generate heat, and cause parts of the carbon bed to smoulder.

Hotspots could damage the filter unit and other equipment, and cause an unsafe production environment. Once they develop, customers need to exchange the filter as soon as possible, potentially wasting unused carbon.


The INERTI-BOX was developed in response to client concerns about hotspots.

The inertisation process is based on nitrogen dosing, electrical controls and a carbon monoxide (CO) sensor. If the sensor detects a hotspot forming, the filter valves are closed, cutting off the air supply. The INERTI-BOX then douses the filter with nitrogen, reducing the oxygen levels and eliminating the risk of a hotspot developing further. This procedure takes place automatically, with no need for an operator.

The INERTI-BOX must be installed and tested at each customer’s site. This can take one to three days depending on the set-up on site. DESOTEC has recently created a new type of INERTI-BOX that can operate up to three filters in parallel or in series. Because of this adaptation it is no longer necessary to flush all filters with nitrogen in case of a hotspot. This reduces the nitrogen consumption and makes sure that the filter(s) without hotspots can still be used to treat emissions.


The HC-BOX is combined with the INERTI-BOX to create a turnkey solution for smaller filters and the AIRCON HC and HC-XL model. It is a valve island, containing the inlet, outlet and a bypass valve, with the INERTI-BOX on top. This is connected to a rack with nitrogen bottles.

Up to three HC-BOXES can be used with one INERTI-BOX, with each one able to act independently so that only the affected filter is isolated and doused with nitrogen. Movement of the valves can be automated by connecting the HC-BOX to the PLC of the customer 


One customer in Belgium left a filter unventilated over the weekend after using it all week. When oxygen was added to the filter on the Monday morning, it effectively fanned the hotspot, causing it to smoulder.

The customer ordered a new filter and an INERTI-BOX. We were able to fit this just two days later so that production could restart.

INERTI-BOXES are also widespread in our pharma projects due to the hazardous chemicals used and the potential cost of any downtime.

Two HC-BOXES and one INERTI-BOX are in use at a petrochemical site at the Port of Antwerp, Belgium.

Air emissions monitoring: the VOC-BOX

To determine when to order a filter exchange, customers need to measure the filter outlet to detect any breakthrough of VOC emissions.

They can contract an external company to carry out monitoring at regular intervals, but run the risk of exceeding limits without realising between visits. Handheld devices are also available for certain molecules, but are not always reliable.

As companies seek to improve their environmental performance and meet increasingly strict regulations, accurate and timely emissions monitoring is becoming ever more important.


DESOTEC developed the VOC-BOX in response to customer requests for a continuous emissions monitoring device for their air purification filters.

The VOC-BOX is fixed to the outlet of the filter on a permanent basis. Its technology is based on Flame Ionisation Detection (FID), which is widely recognised as one of the most reliable measurement methods.

Servicing, calibration and upgrading is carried out by an external company, ensuring the VOC-BOX is always accurate and up-to-date.

The biggest advantage of the VOC-BOX is its software platform, which enables customers to view real-time emissions from any device at any time.

Customers can track emissions to see if problems are developing: ideally, they will fit a VOC-BOX at both the inlet and the outlet to determine where the issue lies. They can also set warnings, so they know when they are nearing the point at which they should order a filter exchange.

The VOC-BOX in action

VOC-BOXES are best suited to larger companies with strict CSR commitments. At DESOTEC’s headquarters in Belgium, we have fitted them to our own filters, which treat emissions from the coatings and paints that we use.

Learn more about DESOTEC’s new solutions

Where safety and emissions monitoring are concerned, it is best to turn to the experts. DESOTEC offers reliable solutions that have been developed over many years. By doing this in-house rather than referring customers to third-party suppliers, we keep the filtration process simple for clients. We continually update our technology so that customers have the most advanced equipment available.

To find out which solutions might work best for you, contact our team of engineers today.


At DESOTEC’s facilities, all used carbon is analysed so the right measures can be taken for handling and removing the saturated carbon out of the mobile filters. Used carbon which meets DESOTEC's acception criteria can be reactivated.

This means that all molecules that were adsorbed on the activated carbon at the customers’ site are desorbed inside DESOTEC’s reactivation furnaces. These contaminants are then fully destroyed, in accordance with National and European legislationby an incineration and neutralisation setup. The entire installation and its emissions are under continuous online monitoring, which guarantees that only harmless water vapour is seen exiting the chimney.

In case the saturated carbon does not meet our acceptation criteria, it is being sent for specialized external disposal.