Baghouse Differential Pressure: What To Do When Pressure Becomes Too High or Drops Low

Industrial air filtration is essential for ensuring that air quality is safe and clean in industrial settings. Baghouses, which utilize filter bags, either woven or nonwoven, trap particulate matter from the airstream and are an integral part of the filtration process. However, baghouse systems may experience excessively low- or high-pressure levels without proper maintenance and monitoring. This article provides some tips on troubleshooting and maintaining baghouse systems when the differential pressures are out of balance for normal operating parameters.

What Should My Baghouse Pressure Be?

Baghouse differential pressure drop, or DeltaP, is the pressure difference between the dirty-air side of the baghouse and the clean-air side (across the bags). The quantity of airflow and fabric resistance will determine the differential pressure. As a guideline, baghouse pressures should stay steady between 2″ WG and 6″ WG. It is important to note that optimal differential pressure can be application dependent. However, many factors contribute to the baghouse differential pressure, such as particle size and shape, moisture levels, dust loading, and cleaning effectiveness.

It is a sign that your baghouse filter bags are nearing the end of their lifespan when the pressure reading increases above 6″ and moves closer to 8″ WG after cleaning, and your baghouse requires further maintenance.

Image & Illustration showing optimal baghouse pressures, low baghouse pressure & High Baghouse Pressure | Albarrie

How To Maintain Baghouse Systems When Pressure Becomes Too High

It’s important to identify the source of the pressure irregularity. High differential pressure will increase your energy consumption when using a variable-speed fan since the blower has to work harder to pump air through the system, causing additional wear on the filter bags, solenoids, and diaphragms.

When the baghouse system experiences unexpectedly high-pressure readings, inspect these key maintenance items:

  • Determine if the cleaning system is functioning properly. If the cleaning system isn’t working, the filter bags aren’t cleaned during their cleaning cycles.
    • The material discharge device is no longer operating correctly, is leaking/ drawing air, and dust cannot travel into the upward gas stream.
    • Dust particles are embedded in the filter’s depth and unable to be removed by the dust cleaning cycle, called bag blinding or plugging. This occurs when dust accumulates inside the tiny pores of the fabric and prevents air from flowing through properly. Blinded filter bags more than likely need a full replacement.

    A gradual increase in pressure is often due to excessive dust cake on the filter and dust entering the filter media’s depth. Albarrie recommends on-demand cleaning over timed cleaning as the fabric becomes more aged or penetrated. In this scenario, increased cleaning cycles are required. When properly monitored, this change can be easily recognized, and Albarrie’s High-Efficiency Cleaning can be used to remove the embedded particles, increasing the baghouse filter bag’s life.

    Comparison image showing the different between regular cleaning & Albarrie's HEC Cleaning

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    What To Do When Baghouse Pressure Drops

    A variety of factors can cause low-pressure readings in baghouse systems. A sudden baghouse pressure drop below 2″ WG can indicate a possible filter bag leak, rupture, or plugged ducting. Perform a leak detection test to see if there are any holes within the filter bags, the system’s housing, or other mechanical parts.

    Other common causes of low pressures drops are:

    • The fan is not inducing enough airflow through the system, inspect the fan blades for damage and check for slipping belts.
    • Wet dust can lead to premature clogging, so it’s important to ensure that the baghouse environment is not moist. Confirm baghouse seals are still working effectively and ducting has no holes, which could draw in wet air.
    • The uneven dust loading from a broken or worn inlet deflector can be very troublesome. For example, if the deflector is made of metal, abrasive dust erodes it and alters the airflow over time, not to mention the filter sandblasting potential. As a result, some filters may become overloaded with dust while others don’t receive as much – causing those loaded down to plug faster and raise pressure drop levels throughout your system.
    • Cleaning becomes challenging when the venturi is out of alignment, or the filter bag cage fits poorly. Bags need to expand to dislodge dust particles. If the airflow isn’t properly delivered, the bags won’t inflate correctly and will not get cleaned. Any obstruction that prevents full inflation can lead to premature plugging and cause baghouse operational issues.

    It’s important to monitor your baghouse’s differential pressure reading and take action when it deviates from its normal range for extended periods of time. Investing in regular maintenance and troubleshooting can reduce energy costs, prevent costly repairs, and ensure optimal performance of your baghouse.