15/09/2026
Baghouse Leak Detection: From Guesswork to Targeted Inspection
When a tiny leak becomes a big problem, how do you find it?
In a baghouse, hundreds or even thousands of filter bags may be working at the same time.
The challenge is not always detecting that something is wrong — it is finding exactly where the leak is.
A small pinhole, damaged seam, or poor sealing at the bag-to-tubesheet connection can allow dust to bypass the filtration system. By the time the problem becomes visible in emission data, the damage may already be significant.
One technique we find particularly useful for pinpointing these hidden leaks is fluorescent powder leak detection.
How does it work?
The principle is relatively simple:
Tracer powder → Airflow → Leak → Fluorescent signal
A controlled amount of fluorescent powder is introduced into the inlet of the baghouse. The powder follows the airflow and deposits on the filter bags.
Where there is a defect, some of the tracer particles pass through the damaged area and accumulate on the clean-air side.
Under a suitable UV inspection lamp, typically around 365 nm, these particles become highly visible, turning an otherwise invisible leak into a clearly identifiable fluorescent spot.
A typical inspection process
1️⃣ Introduce the tracer powder
Keep the filtration system operating under suitable conditions and distribute the powder evenly through the inlet airflow.
2️⃣ Allow sufficient circulation
Give the tracer time to reach and interact with the filter bags.
3️⃣ Inspect under UV light
With the clean-air chamber darkened, scan the tubesheet, bag openings and bag surfaces with a fluorescent inspection lamp.
4️⃣ Mark and repair
Once a fluorescent spot is identified, mark the location, document it, and repair or replace the affected filter bag.
The method can be especially useful for locating:
• Pinholes and small tears
• Damaged stitching
• Bag-to-tubesheet sealing problems
• Installation-related damage
• Localized leakage that conventional inspection may miss
Why does it matter?
Traditional inspection methods can tell us that a filtration system has a problem, but they don't always tell us which bag is responsible.
Fluorescent powder provides a visual tracer, making the leakage path much easier to identify.
This can help maintenance teams:
→ Reduce inspection time
→ Avoid unnecessary replacement of good filter bags
→ Identify problems at an early stage
→ Improve emission control
→ Build a more preventive maintenance routine
For large baghouses, the difference between “there is a leak” and “this is the exact bag and location” can mean a lot in terms of maintenance time and operating cost.
Fluorescent powder leak detection is also covered by DL/T 1829-2018, Technical Specification for Fluorescent Powder Leak Detection of Bag Filters in Thermal Power Plants, providing a standardized reference for its application in the power industry.
At Filmedia, we believe good filtration is not only about choosing the right filter media. Inspection, installation, sealing and maintenance all play a role in keeping a filtration system performing as designed.
Sometimes, the smallest leak deserves the closest attention.
