"BLACK LIGHT TEST" - LEAK DETECTION
PURPOSE: The purpose of the "Black Light Test" is to locate air/dust leaks in a baghouse between the clean and dirty
DESCRIPTION: A bright fluorescent powder is fed into the inlet duct work of the baghouse where the particles are
dispersed uniformly in the airstream. The fluorescent powder is collected on the bags in the same manner as the dust
particles. Should there be a leak in any of the bags, the connection of the bag to the tubesheet, or in the seams of the
tubesheet, the powder will pass through to the clean side where it can be detected with the use of a ultraviolet lamp.
- Ultraviolet lamp
- Fluorescent powder, green
- Fluorescent powder, orange
Test at night (or in a darkened condition)
Start induced draft fan.
Slowly feed one color of powder into the inlet duct at the hood, a duct clean out door, or any convenient location
upstream of the baghouse.
Dirty baghouse: 1 lb./1000 sq. ft. cloth area
Clean baghouse: 1/2 lb./1000 sq. ft. cloth area
Shut down fan.
Use proper LOCKOUT/TAGOUT devices on all energy sources before entering the baghouse.
Enter the clean air side of the baghouse with the ultraviolet lamp turned on and search for signs of the fluorescent
powder which will glow either green or orange where the powder has leaked through.
around the perimeter of the tubesheet where it attaches to the wall.
at each seam of the tubesheet where it is made in multiple sections.
around the perimeter at the top of each bag where it attaches to the tubesheet.
down inside the bag.
If fluorescent powder is found, determine the cause of the leakage, and correct by;
welding or caulking the tubesheet.
removing the bag and reattaching to the tubesheet properly.
replacing any bags found to be leaking through holes.
Note: New bags have a higher porosity than used bags. It is not uncommon for dust or the
fluorescent powder to bleed through the fabric or needle holes of new bags in small quantities.
This condition is only temporary and should cease after a few hours of operation.
Repeat steps #1 - 7 with a different color of powder until all leaks are eliminated.