How to Maintain & Operate Dust Collectors Using Differential Pressure

Consistently high DP is a sign that your filters are blinded (i.e. fabric fully saturated with dust particles). Once blinded, filters can no longer be cleaned and must be replaced.

Blinded filters or even filters with large temporary dust cake buildup will have higher emissions (i.e. leaking). Check with opacity meters or broken bag detectors to verify emissions levels

Insufficient air to cloth ratio for application will result in the bags being overloaded with dust and the cleaning system will be unable to effectively clean the bags.

Abnormally low DP (below 3 in.) can be a sign of holes, tears, or loose seams in the bags or that the filters are not installed properly (misaligned snap band on top load models, loose bag clamps on bottom load units).

In a pulse jet dust collector this could be caused by low compressed air pressure, contaminated air (dirt, water, or oil in air reservoir), misaligned installed blow pipes or misaligned/missing cage venturi.

If the cleaning cycles (i.e. air pulses) are not set correctly the bags will not be cleaned properly. (“On time” is how long the pulse valve is opened. If set too long the air burst will be too weak to clean the bag. If set too short, it will not release enough air to clean the entire length of the bag.)

The order the bags are cleaned (called “firing sequence”) should be staggered (1, 4, 2, 5, 3, 6) so that successive rows are not cleaned one after another (e.g. 1, 2, 3, 4, 5, 6,).

Over-cleaning of bags will place undue wear on the filters and lead to early failure.

While if the compressed air pressure is too high it will clean the filters better, it also will lead to early bag failure, often creating abrasion problems or even creating holes in the fabric.

Since emissions are at their highest when the filters are pulsed, over pulsing leads to increased emissions

Sudden changes in DP can be caused by upset conditions or changes in the process the system is venting. Any problems in the dust collector could be a sign that something potentially far more serious is taking place further upstream from the unit.

Consistently high DP might be a sign that the system is undersized and not able to keep up with the load placed on it.

Worn out baffle plates, dropout boxes, and poor airflow design lead to overloading of filters and high DP.

Excessive dust build-up in the hopper can lead to dust re-entrainment and overload the filters.

Wet or sticky dust--which is difficult to clean--can be a sign of leaks near the hatches or cracks in the baghouse structure that allow moisture or cold air to enter causing condensation on the filters.