Dust Extractor Classification

TNO Performance Tests are conducted on complete systems (tool, extraction unit, tubing and vacuum extractor). The principle of “equivalence” is applied to both the tools and the extractors. This means that no additional test is required on comparable systems (tools or extractors). TNO determines when this applies.

To compare the performance of different vacuum extractors, TNO has developed a standard test. This is carried out using an industrial vacuum extractor in combination with a 125 mm Metabo angle grinder, model WE 9-125 Quick (900 W), fitted with a TNO dust shroud. The tool is operated continuously for 60 minutes, grinding sand-lime brick. During this time a groove 60 metres in length is produced. Approximately 7.0 kg of crystalline silica dust is collected in the extractor. The results are presented in the form of a label, as shown below.

The label shows the total “responsible operating time” in hours – between one and eight – per eight-hour working day. That is the length of the time for which the system can be operated without exceeding the statutory occupational exposure limits for hazardous substances such as crystalline silica and hardwood dust, as measured in the “employee inhalation zone”. The standards applied are the eight-hour time-weighted average Workplace Exposure Limits (GSW TGG-8u) listed on the website of the Social and Economic Council of the Netherlands (Sociaal Economische Raad, SER).

IMPORTANT! The above label applies only to the complete system tested (tool, extraction unit, tubing and vacuum extractor together) and must never be usedtoindicate the performance of an extractor alone.

To allow for effective comparison of these devices in their own right, a second label has been developed exclusively for vacuum dust extractors. An example of that is shown below. The rules for the use of these labels can be found in our Labelling Guidelines. The labels themselves can also be downloaded there.

This label shows which classification category a vacuum dust extractor falls into. TNO has defined four of these.


Operational capacity (airflow in m³/h)*

TNO label 

Class A

> 150

 5-8 hours

Class B


 2-4 hours

Class C

≤ 100

 1 hour

Class D

 For wood-dust extractors only.


* Capacity measured after test, at end of hose after filter has been cleaned.

To qualify for a particular category, an extractor must comply with both its capacity and its TNO labelling requirements. All class A, B and C devices are also suitable for wood-dust extraction.

Dust extractor comparison and substitution

The above classification system enables the easy comparison of different vacuum extractors. A device tested in accordance with protocol described earlier, using the combination of the TNO reference angle grinder and a TNO dust shroud, can only be replaced with one in the same or a higher category and holding at least the same label for “responsible operating time”. The highest possible combination is Class A with an “8-hour” label.

Filter cleaning

We distinguish between three types of filter cleaning.

 - Automatic. Cleaning is triggered automatically by a timer or a pressure sensor.

- Semi-automatic. The filter is cleaned every time the extractor is switched on.

- Manual. The operator has to initiate cleaning.


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