DIY: How to extend the life of the HEPA filter in a Bright kitchen hood?

Today our “People’s Expert” action is continued by Andrey Kashkarov: St. Petersburg innovator tells us how to equip the Bright hood or any similar economy class with the new indicator of external filter pollution. Such household trickery will help to prolong the life of an expensive HEPA-filter and save a lot of money.

Extractor hoods

As is known, HEPA High Efficiency Particulate Arrestance activated charcoal filters are used in places with high demands on air cleanliness.

They trap from 85 to 99.95 percent of grease allergens and contaminants down to 0.001 microns in size – these particles are tens of times smaller than S-class filters in “budget” models.

But nothing lasts forever, even the HEPA filters need to be replaced every two years or so. And this is not a cheap pleasure. This raises the question of whether it is possible to save money here?

Can! And here’s how: you need to equip the economy hood with an air cleanliness indicator and sensor. These devices will help to signal SOS in time, having found impenetrable growths on the external filter – an acrylic type of filter KR-60 installed just behind the air intake grille.

Andrei Kashkarov: on the brink of new ideas

The sensor will work and neon indicator will blink – it will be a signal for urgent replacement of cheap external filter: throw away cheap one, but save expensive internal one.

Anyone can do simple modifications to the hood.

What to work with: the Bright kitchen hood

The Bright hood differs from other models in the same price range in technical characteristics: low noise level at maximum mode – only 51 dB and air capacity – not less than 250 m³/h.

Bright Bright Bright has replaceable activated carbon and acrylic grease filters KR-60 .

Three speed modes, provides one motor-fan. The other parameters are similar to other models of kitchen cooker hoods.

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Fig.1 – View of a complete Bright kitchen hood.

Let’s get started: Sensor, indicator and tube

For our modification we chose a very sensitive sensor CG-P1 and a light indicator in the form of a neon lamp. The sensor can be bought separately or can be removed from a modern vacuum cleaner, for example, Elenberg VS-2015 with the maximum power of 1400 W. Fig. 2 is a view of the open housing of a portable vacuum cleaner with a dust sensor.


Technical characteristics of the CG-P1 dust indicator

  • current up to 20 mA
  • 250VAC voltage
  • Operating temperature range including temperature of incoming air 0 … 95 ° C
  • Max. input air pressure 5 kPa.

CG-P1 dust sensor is designed for automatic shutdown. It can be used as a safety device and indication in dust collectors and different types of hoods.

The principle of the dust sensor is simple. The sensor is equipped with a thin inner diameter 0.8 mm, outer diameter 1.2 mm polychlorvinyl tube length 25 cm . On one side the tube is connected to the CG-P1 fig. 2 , and the other end goes directly into the bag of the dust collector of the vacuum cleaner, before the suction bell of the electric motor fan.

The suction starts to slow down when the dust canister is full, and the concentration of dust rises in the suction airflow, which starts to “bombard” the CG-P1 sensor through the tube. As a result, the sensor changes its internal resistance from units of ohms to tens and hundreds – according to the graph shown in Fig. 4.

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Figure. 4. Diagram of CG-P1 sensor resistance dependence kOhm on axis OH on pollution of the air flow in % on axis OH

By the way, the tube material can also be other – for example, similar to a medical dropper with a small inner diameter.

I would like to point out that the dust sensor CG-P1 is not dismountable, not maintainable, and does not need external care and cleaning. The products are available in the following nominal diameters, mm : DN 25-40-50-65-80-150 – according to the intended use and the volume of the air flow to be controlled. In domestic vacuum cleaners, I have only encountered 25 and 40-mm sensors.

The change of resistance sensitivity adjustment can only be done manually by turning the eccentric shaft in the sensor face the slot is made by a Phillips screwdriver clockwise. For this purpose, a hole is made in the sensor for a screw.

Connect the sensor into an electrical circuit – according to the diagram in Fig. 5.

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Fig. 5. Wiring diagram for a dust sensor and indicator lamp

Any neon bulb is used as an indicator, in which the gas starts to glow even with a small current in the circuit, which corresponds to a small change in resistance of the CG-P1 high-resistance sensor.

You can also use a miniature light from the lighting of modern light switches and fans as a neon lamp.

In a vacuum cleaner the indicator lamp is installed on the case. When transferring the dust sensor in the case of a Bright hood or similar , the lamp is also taken out on the front panel – for visual control of contamination of internal filters.

Where to put the sensor and indicator lamp in the hood?

The CG-P1 dust sensor itself is mounted inside the hood in any suitable position, as shown in Fig. 6.

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Fig. 6. Installing the CG-P1 dust sensor inside a Bright hood

To install the dust sensor and the indicator in the kitchen hood, open the bottom lid of the hood with the KR-60 filter see Catalogue 33, page 54 . Fig. 7 .

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Rice. 7. The lower part of the housing with a place to install the acrylic filter KR-60

What is better not to do: We do not recommend using in the kitchen hood equipped with S-class filter or HEPA filter with ineffective, multi-use cloth dust collectors: the worse the air purification, the earlier the expensive HEPA filter will break down.

Using a screwdriver, drill a hole for fixing the sensor and neon indicator. Then, fix the sensor near to the inlet socket of the hood suction fan with a self-tapping screw.

The air intake pipe is located directly in front of the suction bell to do this, you will need to remove the round carbon filter of the hood, shown in Fig. 8 and fix it with a strip of adhesive tape.

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Fig. 8. A view of the Bright cooker hood charcoal filter

The kitchen hood retrofit is now complete. Similarly, the dust sensor with indicator can be added to other industrial and home-made devices. For example, you could make an automatic hood for the soldering station in your home lab.

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