Electrical Projects Air purifiers come in many shapes and sizes, and so many different principles are used that it would take an entire book to discuss them all. Basically, air purifiers work by urawing the air into the unit, processing it, and expelling it as cleaned air. Sometimes the processing is done by chemicals, sometimes by filtration, and sometimes by subjecting the air to ultraviolet rays or high-voltage dc. Some units combine a number of these operations.

Such an air purifier is illustrated by the exploded view at Fig. 5-13. The unit shown can be operated in two modes—"odor only" and "total filtration." In the "odor only" mode, outside air is drawn into the front and through a chemical filter which removes odors from the air. It is then expelled out the rear of the unit. The chemical used in this case is a form of charcoal, and the manufacturer recommends that the filter pack be replaced every 3 months. At the same time the plastic filter, located behind the rear grille, should also be removed and washed.

In the "total filtration" mode, air is passed from the front of the unit through the chemical filter and then through an electrostatic precipitator before exiting out the rear of the machine. The electrostatic-precipitator section consists of a positively charged ionizer wire and a negatively charged collector plate. The difference of potential between the ionizer wire and the collector plate is approximately 6200V dc. As air passes through the precipitator, dust and other tiny particles in the air are positively charged by the ionizer wire. The positively charged particles are then strongly attracted to the negatively charged collector plate, and they are removed from the air and collect on the plate. As shown by the wiring diagram at Fig. 5-14, the high voltage for the precipitator section is obtained by using a stepup transformer and a voltage-doubling rectifier circuit.




Page 1 2 3 4 5 6 7
Home > Electrical Projects > Repairs > Air Purifiers

Febuaury 10, 2012