Exhaust system test: Bernardo DC 250 CF

Exhaust system test: Bernardo DC 250 CF: system

Everyone should be aware that sanding dust or sawdust should be extracted during work. However, workshop vacuums are quickly overtaxed, especially with sawing and milling chips. Although they reach a high negative pressure but too large chips clog the hose and small dust bags must be changed frequently. This could get expensive.

Advantageous here are Zyklonabscheider that separate coarse chips and simply drop into a collection. The filter itself only has to absorb the fine dust. An extraction system combines this function with a very large filter, which on the one hand ensures effective separation of dust while maintaining the same suction power, but on the other hand also reduces the flow noise of the air.

In the test today we have the extraction system DC 250 CF by Bernardo, which was kindly provided by the online shop HSH24.net. With a suction capacity of 1500 m³ / h and an online price of € 345, it should fit into the budget of many DIY enthusiasts.

Technical data Suction unit Bernardo DC 250 CF
(Manufacturer)

Air flow: 1500 m³ / h
Filter area: 2.25 m²
Max. Negative pressure: 1020 Pa
Extraction connection: Ø 100 mm
Chip bag contents: 60 l (flexible)
Idling speed: 2950 rpm
Sound pressure: 86.5 dB
Motor power consumption: 1000 W
Voltage 230 V / 50 Hz
Machine dimensions (W x D x H): 850 x 380 x 1420 mm
Weight approx. 34 kg
Delivery and the first impression
The extraction system was delivered ready assembled via a forwarding agency. Since the device has not reached us as a typical order and it also means in an Amazon review that it needs to be set up, I can not say if this is the typical shipping route. But if you look at the construction, your own structure should not be a problem either.

Exhaust system test: Bernardo DC 250 CF: exhaust

Exhaust system test: Bernardo DC 250 CF: system

Extractor Bernardo DC 250 CF
Extractor Bernardo DC 250 CF

Even if my workshop is quite low, which reinforces the impression, it can not be denied that the exhaust system with a height of almost 1.5 m already claimed a decent place. If you look more closely at the structure, it becomes clear what is responsible for it. It is the big dirt bag, which must be located below for functional reasons. Without it, the device would only be half as high.

Also very large is the fine dust filter - this can not hide, of course. Certainly, the filter could make smaller, but this would again disadvantages. Who wants a good and above all constant suction, achieves that only over a large filter surface. The smaller it is, the more air must pass through the filter surface, which causes heavy noise and more quickly clogs up the filter. A large particulate filter is therefore inevitable.

Overall, nothing can be criticized for the construction of the Bernardo DC 250 CF. The construction is convenient and simple, which ensures easy cleaning and maintenance. Also, the build quality is no reason for criticism. Everything is stable and neatly bolted and the paint job is flawless. Important safety instructions are clearly visible.

The extraction system can be operated by a safety switch - automatic switch-on is only available as an accessory. However, considering that the vacuum cleaner is intended for large milling and planing machines, this is of course understandable. Such machines rarely run with 230 V and the obligatory outlet, as on many workshop vacuum cleaners, makes little sense here.

Structure and function of the dirt separation
The separation of coarse dirt and dust is primarily by a fairly simple but quite effective cyclone principle, as it is used in many bagless cyclone suction cups. Even many home improvement build similar variants.

Exhaust system test: Bernardo DC 250 CF: exhaust

Function of a cyclone separator
Function of a cyclone separator

When recording from the top is clearly seen how the fan blows the sucked air with the dirt laterally in the round dirt pickup. This creates a vortex in the collecting tank, which makes the entire air spin like a whirlpool.

As a result of the centrifugal force, heavier particles are pressed outwards against the edge and drag there on the housing. So you lose speed, the centrifugal force decreases and they fall down into sack. Only slight dust particles pass through the exhaust air to the filter and are caught there.

This method prevents the filter from becoming clogged with chips, which would decrease the suction power. Even if the chip collecting container is almost full, this does not affect the filtering effect or suction performance. Furthermore, such a cyclone separator allows the use of different containers for dirt separation. With the appropriate opening and an airtight body, also barrels or sacks of a different size can be used, without affecting the function of the extraction system.

Fine dust filter cartridge with manual cleaning
The very large filter ensures a light and therefore almost silent air outlet. Slats increase the filter area. Nevertheless, it happens over time, of course, that even such a large filter surface is clogged with fine dust. Smaller professional teat set in this case on the automatic knocking of the filter. Of course, this is not possible with such a filter cartridge as used in the extraction system. Nevertheless, such a function does not have to be dispensed with. With a large handle, which moves inside spring-loaded brushes, the filter can be knocked out manually. Due to the filter size, this solution is absolutely sufficient.

If the filter cartridge needs to be thoroughly cleaned or even replaced, this is done in a fairly simple way. Like the dirt bag, the filter cartridge is held with a strap, which can be solved without tools with a handle. The rubber seal sits quite taut and slips only with a bit of force, but lubricants should still be dispensed with, so that the collected chips remain dry and do not stick.

Exhaust system test: Bernardo DC 250 CF: bernardo

Quick release with tension straps that do not require a tool.
Quick release of the straps without tools.

Exhaust system test: Bernardo DC 250 CF: test

Mechanically simple solution to clean the filter cartridge.
Mechanically simple solution to clean the filter cartridge.

Overall, the separation of dirt and filtration of the exhaust air is quite simple but functionally implemented. Of course, this has the advantage that errors can be corrected quickly or parts can be easily replaced. Repair and filter replacement can be done by any user, reducing running costs and minimizing downtime.

Extractor Bernardo DC 250 CF in a practical test
The function as a bottom sucker is just a bonus
Even if the Bernardo exhaust system is shown in pictures as a vacuum and this function is also specified in the description, the possibility after consultation with Bernardo is only a bonus. After my first test I have to confirm unfortunately.

Exhaust system test: Bernardo DC 250 CF: test

Floor nozzle with good suction power but not adjustable.
Floor nozzle with good suction power but not adjustable.

The suction power is given as 1500 m³ / h (equivalent to 25 m³ / min or 417 l / s) and clearly noticeable at the floor nozzle. The dirt is picked up easily from my workshop floor and even sand is sucked out of the board joints. Even leaves that get into the workshop when opening the front door do not stop the DC 250 CF. Accordingly, there is nothing wrong with the suction power.

In use, however, it quickly becomes apparent that the extraction system was not built as a floor vacuum and can not generally be used for this purpose. The first indication for this is a fairly simple implementation of the floor nozzle, which was not adjustable. It can not be adapted to specific requirements.

In the second point, the very small roles in many workshops are disadvantageous. As can be seen in the pictures, plates with joints are laid in my workshop. In these, the rollers hang and it is not possible to push the suction evenly over the ground. Added to this is the weight distribution with an overhead center of gravity. If the rollers hang in a joint or any heels, the teat tilts very quickly. Of course, anyone who owns a very smooth workshop floor is not affected by it and can certainly suck his bottom with the Bernardo extraction system.

Exhaust system test: Bernardo DC 250 CF: exhaust

By very small roles, the "floor vacuum cleaner" quickly gets stuck.
Due to very small rollers, the vacuum cleaner tends to tip over.

Exhaust system test: Bernardo DC 250 CF: exhaust

Foliage and larger pieces can clog the intake.
Foliage and larger pieces can clog the intake.

The DC 250 CF as machine vacuum with aha effect
Although the extraction system from Bernardo is supplied as a floor vacuum, its application lies in chip extraction on larger woodworking machines. On larger woodworking machines... Which I also had to learn first.

The hose on the floor nozzle is released quickly and in your hand you hold a suction hose with a diameter of 100 mm. How can I get that to my machines? These almost always have a suction connection for typical workshop vacuums with 35 mm.

Exhaust system test: Bernardo DC 250 CF: test

On the 3D printer a tailor-made adapter was created.
On the 3D printer a tailor-made adapter was created.

Exhaust system test: Bernardo DC 250 CF: system

A well meant but unfortunately unsuccessful implementation.
A well meant but unfortunately unsuccessful implementation.

As a fan of 3D printing, I have designed an adapter that can be mounted in the 100 mm suction hose and provides a connection with locking for the suction hose of my workshop vacuum cleaner. The result was great, had only one drawback: The suction power was minimalist and a test on my tools was unnecessary. what happened there? Is something broken? A call to Bernardo clarified:

There are two variants of the extraction:

The motor with fan wheel is located behind the chip collector, as it is known in typical vacuum cleaners. It is advantageous that the fan does not come into contact with the dirt and therefore can work with very well fitting wings that provide a decent negative pressure. The disadvantage, however, is that the filter must be in a housing and therefore can not be very large.
The engine sits in front of the filter and the sucked chips fly through the fan. An advantage is the independence of the filter, as the air is pushed in and can escape everywhere. The size of the filter is therefore not limited. A disadvantage, however, is that the fan must be constructed so that it is not clogged by the sucked chips, or damaged. Although very large volumes of air can be carried in this design, a high negative pressure does not build up.
These variants are comparable with a domestic waterworks and a dirt or submersible pump. A simple submersible pump delivers with about 780 W easily up to 15000 l / h, taking stones with a diameter of 3 cm. However, if you reduce the discharge, the flow rate decreases rapidly and the pressure is not even enough to effectively run a lawn sprinkler. A domestic water plant with similar power consumption only delivers around 3 - 4,000 l / h, but builds up a pressure of up to 4 bar.

The reason why the DC 250 CF extraction system from Bernardo can only be operated with a 100 mm suction hose (reducible to 70 mm according to Bernardo) is therefore physically justified and not a defect. Nevertheless, I find it a great pity that neither in sales, nor in the manual is pointed out.

It is quite possible to use suction systems with a large suction diameter for smaller machines, as it may happen that mainly large machines are used for woodworking, which have a suction connection with 100 mm and, incidentally, the router is used. The magic word is called "amount of air". No matter which tool or hose is connected, a large air passage (diameter 100 mm) must be guaranteed.

For larger devices, such as the table saw, it is possible to convert this to a larger connection. For example, if the table saw stands on a mobile stand, it can easily be vacuumed from below.
In order not to reduce the amount of air, the exhaust can also be branched to ensure with several openings the required air passage.
1. Connection of a table saw to a suction system with a large suction hose.
As the first picture shows, many shavings quickly collect under my table saw. It should therefore be possible to suck off the resulting chips under the table saw. For this purpose, a hole is sawn into the plate of the mobile base and a 100 mm hose connection, as it is available for ventilation systems, screwed. This can then be attached to the suction hose. Since it is a standard measure, the conversion is carried out quickly.

Exhaust system test: Bernardo DC 250 CF: system

Under the saw, the table is suitable for extraction.
Under the saw, the table is suitable for extraction.

Exhaust system test: Bernardo DC 250 CF: exhaust

Simple connecting piece of an extractor hood.
Simple connecting piece of an extractor hood.

For the test, I connected the rather short hose, so that the Bernardo exhaust system is directly behind the saw. For real use, you should equip yourself with a longer suction hose, which is available as an accessory.

The result has already turned out very well without any special modifications. Except for a few shavings that can never be avoided with a circular saw, the work environment remained surprisingly clean. With a few measures to seal the housing or a targeted positioning of the suction hose in the saw, the result should be even better.

Exhaust system test: Bernardo DC 250 CF: bernardo

To machine connection another hose is needed.
To machine connection another hose is needed.

Exhaust system test: Bernardo DC 250 CF: bernardo

The workplace stays clean.
The workplace stays clean.

2. Preservation of the air volume by a Nebenzug.
If the use of a smaller suction hose can not be avoided, according to the manufacturer, the suction behavior should be improved if sufficient "secondary air" is provided. This can be realized by a Y-distribution in which one side remains open.

Please do not be fooled by this. Two tubes with an opening of 50 mm do not give the diameter of a tube of 100 mm. As a check, the surface area of ​​the opening should be calculated. A pipe with an opening of 100 mm has an area of ​​78.54 cm². A 50er tube, however, only 19.64 cm ². Accordingly, four openings of 50 mm diameter are needed to replace an opening of 100 mm.

Well can be used for this purpose parts of a plastic downpipe. These have, like the hose connection of the suction system, a nominal diameter of 100 mm and can be reduced to 70mm. I have used this and used my previously created adapter. The 70s branch remained open here.

Exhaust system test: Bernardo DC 250 CF: bernardo

Important: secondary train with slim hoses.
Important: secondary train with slim hoses.

Exhaust system test: Bernardo DC 250 CF: system

With a thin suction hose sufficient suction power.
With a thin suction hose sufficient suction power.

The suction performance improves slightly compared to the first test - without an open branch - but does not replace a workshop vacuum cleaner. In combination with a router, however, I found the suction behavior sufficient. One should not forget that such a suction system is not intended for small suction hoses.

Simple but effective cleaning of the fine dust filter
As described above, the Bernardo extraction system has a large bracket, which can be manually rotated to filter cleaning. Inside, long brushes "shake" the filter surface to release settled dust. How well that works, shows the simple little test.

After my test work, I have the filter cartridge (without cleaning) removed and placed on the workbench. Clearly visible in the photo are the added grooves. After only 2-3 turns, the dust is on my workbench. The final photo shows the filter cartridge without any further cleaning. The dust is completely removed.

Exhaust system test: Bernardo DC 250 CF: bernardo

Dirty filter cartridge
Dirty filter cartridge

Exhaust system test: Bernardo DC 250 CF: bernardo

After cleaning, dissolved dust
After cleaning, dissolved dust

Exhaust system test: Bernardo DC 250 CF: test

Simple but perfect cleaning
Simple but perfect cleaning

Conclusion for the extraction system Bernardo DC 250 CF

Exhaust system test: Bernardo DC 250 CF: exhaust

The Bernardo DC 250 CF extraction system captivates at first by a very large filter cartridge, which ensures a long-lasting, even with heavy dust load for a consistent suction. If these eventually go away, it will take up to three revolutions on the large bracket to effectively release the attached dust from the cartridge.

The entire system is just as simple, so that the term "system" hardly fits. The simplicity is useful in this case. Chips have to be sucked off on a large scale and separated in the filter area. Any bells and whistles would obstruct the passage of air and make maintenance difficult. The structure is thus solved meaningful and the cyclone separator works perfectly.

Suction unit Bernardo DC 250 CF Test mark
Also on the suction power on the original suction hose with a diameter of 100 mm is nothing to complain about. There are certainly some chips through, which are collected in a large plastic bag. Using a quick release this is changed within a few minutes.

Even though there is absolutely nothing to be done about the exhaust system up to this point, the inadequate information has caused some annoyance.

The Bernardo DC 250 CF is offered as a "bottom suction unit and extraction unit for woodworking machines" and the construction when buying corresponds to a floor vacuum. As such, however, the extraction system is only partially usable. The very small rollers in combination with a high center of gravity ensure that the suction system can not be pushed on uneven surfaces and tilts even with small obstacles or holes. There is also a fixed floor nozzle that can not be adapted to your own requirements.
The extraction system is equipped with a suction hose of 100 mm. However, there are a number of adapters and the idea is obvious to use the extraction system for routers or circular saws. Unfortunately, this does not work because the DC 250 CF requires sufficient airflow and only produces a relatively low vacuum. For thin hoses, the exhaust system is not suitable, for which there is no indication either at the time of sale or in the operating instructions. A better education would be desirable.
Anyone who uses the extraction system on large machines with a large suction opening will be absolutely satisfied with the Bernardo DC 250 CF and can rate it for itself with five stars.

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