Matsushima Measure Tech Co., Ltd. >  TECHNOLOGY INFORMATION >  How does Bag Filter work? Structure & Principle

How does Bag Filter work? Structure & Principle


The Bag Filter is a dust control device whose purpose is removing the dust contained in the exhaust gases from industrial process. It is applied to the various applications with different temperature and type of gasses by selecting the filter media accordingly.
The advantage of Bag Filter over the cyclone collector is that it can collect the submicron particles.


The Bag Filter separates dust from the exhaust gas by collecting them with the filter media. The dust is accumulated on the surface of filter media. And the filter media is cleaned by reverse airflow called backwashing (pulse-jet).
The Bag Filter has a selection of filter media. The materials from which the filter is made varies from polyester, heat-resistant nylon to glass fiber. It is selected depending on the conditions such as characteristics of gas or dust. 
The filter media is consumable parts. When it is damaged or worn, the dust may leak outdoors.
Nowadays, Triboelectric Dust Monitor is installed at the downstream of Bag Filter so that it can find the dust leaks and prevent the air pollution.

Predictive Maintenance for Filter Media

The life expectancy of filter media depends on the applications and type of gases to be cleaned. Thus, it is not easy to forecast a demand for replacement.
In predictive maintenance, the Dust Monitor continuously monitors dust concentration on the downstream. It suggests when the filter replacement should be carried out by finding the minor dust increase. As a result, it prevents the dust leaks and optimizes the filter replacement frequency, thereby reducing the operational cost of Bag Filter.
In general, there are 2 main principles of Dust Monitor, Optical type, and Triboelectric type.
Matsushima Measure Tech’s Dust Monitor is Triboelectric type that we’ve supplied over the past 20 years.



For Detection of leakage of dust collector and bag filter breakage
Concentration 0.1mg/㎥~1000mg/㎥
Gas flow rate 4.0 m/s or greater
Output signal 4 to 20 mADC (500Ω)
Contact output
: 2 NONC contact for upper limit alarm,
: 1 NONC contact for fault alarm

Dust Monitor continuously measures for 24 h the dust in exhaust gas at the secondary side of a dust collector or the like and outputs the alarm signal at the abnormal condition and monitors the relative variation of dust amount with an analog signal. It detects the triboelectric charge of dust hitting the sensor probe and make outputs relative to the dust amount. Dust Monitor can be easily mounted on the existing facility to facilitate environmental management.

Learn about DUST MONITOR



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