Plasma air ionisation

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Plasma air ionisation

How do air ionisers work?

An ion is an atom or molecule that carries a positive or negative electric charge as a result of having lost or gained one or more electrons. Ionisation is the process by which this happens. It is useful in air purification because charged air atoms and molecules (ions) act effectively against odours and airborne contaminants.

There are several mechanisms for creating ionised air. A common method used in commercial air ionisers is to apply a high voltage to one or more needles acting as electrodes. This sends the electrons in the internal circuit towards the point of the needle, pushing them together. Electrons naturally repel each other, so, as they reach the tip, they jump off and land on the nearest air molecule or airborne particle, giving it a negative charge. As all the particles have the same negative charge, they are repelled from each other and attracted to earth. The air is therefore cleared as the particles reach earthed surfaces such as walls and ceilings. In addition, ions collide with airborne bacteria and viruses, damaging them and rendering them harmless.

A more effective method – and one which doesn’t result in a film on walls and ceilings – is to use a dielectric discharge tube. This is a glass tube with two wire mesh electrodes, one wrapped around the inside and one wrapped around the outside.

A high voltage is applied to the inner electrode, whilst the outer one is earthed. Because the glass dielectric is an insulator, an electric field builds up and excites the air molecules passing over the surface. Ions, including activated oxygen atoms and hydroxyl radicals, are formed in the resulting plasma. Plasma is a phase of matter distinct from solids, liquids and normal gases, and is known as the fourth state of matter.

Using an alternating voltage, both positive and negative ions are produced. This has a big advantage over single ion polarity systems. As ions dispersing around the room latch on to contaminant particles, those with opposite charges are attracted to each other. This creates larger particle clusters. The air is cleared as these clusters become heavy and fall to the ground, where they can be removed via routine vacuuming or mopping.

The ions also destroy bacteria and viruses by puncturing holes in the cell membranes.

 

Where we use ionisers

Our Ambion 25 and Ambion 100 air ionisers use ionisation to sanitise and de-odourise air in public spaces, whilst our Airconex device ionises air within HVAC systems. We use the highly efficient dielectric tube mechanism.

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