FILTER-ON ESP system works on the principle of two stage electrostatic precipitation. The extracted air which is mixed with fumes / mist / fine dust particles is passed through parallel electrode plates (Ionization section). High voltage is applied across these plates, because of which, the particles in air are charged with positive charge. These charged particles are then passed through another set of parallel electrode plates (Collection section). Here the positive particle is attracted and held on the negatively charged electrode plate and thus gets separated from the air flow. Likewise, the air flow becomes free of particles and we get clean and unpolluted air at the outlet.
As more and more particles are collected on the plate surface, the gap between the electrodes starts to decrease. And thus the leakage current across the electrode plates increases. Beyond certain value of leakage current in the system, a relay trips off the high voltage circuit and shuts down the system by giving an indication on the control panel. At this point, the user needs to take out the filter cell and clean it. After cleaning it, the cell can be put back in the system and switched ON to resume the routine operation.
It depends up on many factors like – the type of pollutant, its quantum, duration of work (e.g. no of hours working / day) etc. The frequency of cleaning could vary from once in a week to once in two months depending on these factors.
Considering the importance of cleaning in operation of this system, FILTER-ON has developed a water soluble cleaning powder for its systems. A solution of this powder can be made in a tank as per the informed proportions and the filter cell is kept in this tank for prescribed time duration (generally ranges between 2-5 min). After this the cell is removed and rinsed by plain water and air dried. After complete drying, the cell can be re-inserted into the system and switched ON.
The filter cell also has a pre-filter and after-filter built in. The pre and after filters are detachable. These pre and after filters have a life of @2-3 years. The electrode plates (which is the major part of the cell) are made of Aluminium. The expected life of plates assembly is @15 years. Thus virtually there is almost NO REPLACEMENT COST.
There are various different filtration efficiency tests recommended as per different standards for various different grades of filters. The Electrostatic filters have the ability to trap very fine particles even up to 0.1 micron size. The filtration efficiency measured as per ASHRAE gravimetric test basis on standard test rig is 95+/-2% for 0.5 micron and above particles. In this test the sample of air is taken at inlet and outlet of the filter. The concentration of the dust in the samples is calculated in mg/M3. Then these values of inlet and outlet are compared. The filter paper used in the sample probes is of 0.5 micron porosity. On the EU grades of filters, this efficiency is better than EU9 Grade filters.
The most common applications in manufacturing industries are Welding Fumes Extraction, Oil Mist and fumes Extraction, Soldering and Brazing Fumes Extraction. In Hotels and Hospitality industry, it is mainly used in Kitchen Fume Extraction system as a Dry Scrubber for kitchen fumes filtration. Other applications include Fresh Air Filtration for incoming outside air for process / food industries, dust proofing systems, Room air purification systems etc.
FILTERON ESP systems offer three very unique advantages:
Thus the long term ownership costs of FITERON systems works out much lower than conventional (media type) systems which requires much higher running cost and replacement costs to achieve the same filtration effect.
Since these systems are working on high voltage charging, it cannot be used for applications which involve explosive dust handling or areas which are flameproof / fire hazardous etc. Because of this limitation, certain applications in chemical of pharma industries cannot be catered.
Though the systems work on high voltage (@12,000 V DC), adequate safety precautions are exercised from design to manufacturing stage. The cabinet of the equipment is connected to ground. Also the construction of unit is such that there is no aces to high voltage related parts when the system is working. So no operator can reach high voltage part when the system is ON. The access door of filter cell as well as control panel are provided with safety switches. If, by mistake, anybody tries to open the system when system is ON, it will get switched OFF immediately preventing any possibility that anybody would touch any ‘live’ part. Also, the doors are generally the screwed knobs with extra-long threading. This prevents immediate opening of the doors. Additionally, FILTERON representative impart a complete operations and maintenance training to the users during installations.