Pulse jet baghouse is the most common dust collection system. In these systems, bags and cages are installed from the clean air plenum, located above the tubesheet. Here are the step-by-step filter bag installation procedures:
1. Identify the Bag’s Top
Begin by orienting the filter bag to locate its top section, which contains the rigid internal metal ring known as the snap band. You’ll typically find a seam or a reinforced area where this snap band is sewn into the fabric; recognizing this helps with proper handling and orientation during installation.
2. Guide the Bag Body into the Tubesheet Hole
- Prepare with a Protective Sleeve: It is highly recommended to use a protective sleeve for this step. This is critical for bag protection, especially for delicate membrane bags, as it prevents tears, punctures, and abrasions from sharp edges on the tubesheet during insertion. Position the protective sleeve on top of the tubesheet hole.
- Insert and Orient the Bag: Carefully slide the filter bag through the protective sleeve and into the tubesheet hole. As you feed the main body of the bag downwards, ensure that the bag’s seam line is positioned in the opposite direction of the airflow from the inlet. This specific orientation helps prevent premature wear and tear on the bag’s seam as it avoids direct impingement from dust-laden air.
- Position for Snap Band: Continue to gently push the bag downwards until the snap band itself is positioned just above the tubesheet hole.
- Remove Sleeve: Once the snap band is correctly positioned, carefully remove the protective sleeve by pulling it upwards over the snap band and off the bag.
3. Deform, Align, and Secure the Snap Band:
- Deform the Band: Gently squeeze or deform the snap band by applying pressure on the side opposite the bag’s seam. This critical alignment is to prevent wrinkles and ensure a proper seal between the snap band and the tubesheet hole. The deformation temporarily reduces its diameter, allowing it to pass into the tubesheet hole. It’s critical to avoid over-bending or kinking the snap band, as this can permanently distort its shape and compromise its ability to form a proper seal.
- Align and Insert: With the band compressed, carefully push it through the tubesheet hole. Meticulously align the snap band’s specific groove with the edge of the tubesheet hole. This precise alignment is essential for a secure fit and helps prevent wrinkles.
- Release and Secure: Once the alignment is perfect, release the pressure on the snap band. Its inherent spring tension will cause it to expand and firmly “snap” into place, creating an airtight seal against the tubesheet.
4. Verify the Seal
After the bag has snapped into place, it’s crucial to confirm its secure installation. Remember, a poor seal allows unfiltered dust to bypass the bag, leading to higher emissions and reduced system efficiency.
- Audible Check: Listen for a distinct “pop” or “snap” sound during the release, which often confirms correct seating.
- Visual Inspection: Visually inspect the bag’s top where it meets the tubesheet from all angles. Ensure there are no visible gaps, wrinkles in the fabric around the band, or any signs of improper seating. The bag should stand perfectly upright and feel securely held by the tubesheet.
- Rotation Test: Gently grasp the snap band and attempt to rotate the bag. If the bag turns or shifts, it indicates that the snap band is not properly seated and the seal is loose, allowing for potential dust bypass. A correctly installed bag will not rotate.