How to maintain your dust collector
The inception of the
dust collector has allowed companies to effectively capture airborne
particulate from an air stream. This has become more important for several
reasons. First, containing particulate — toxic or not — is
necessary to provide a healthy and clean work environment. Second, increasing
local and global awareness of air pollution, containment and the process dust
in industrial applications has emphasized the importance of dust collectors. Finally,
expanding regulations have pressured companies to properly design, install,
operate and maintain dust collection equipment.
To ensure a dust
collector is functioning properly, you need to perform periodic inspections, as
well as repair and replace damaged or malfunctioning equipment. A routine
inspection and maintenance program will boost your equipment's performance and
life. To maintain the health and effectiveness of your dust collector, follow
our helpful list of procedures.
1. Create an inspection/maintenance program — A
typical program consists of a schedule for periodic inspections that are
performed on a daily, weekly, monthly, semi-annual and annual basis. Failing to
periodically inspect the dust collector can hurt its performance. Subsequently,
the dust collector may not meet EPA outlet emissions standards.
2. Don't exceed recommended pressure drop — Sometimes
called differential pressure, it's the amount of static resistance across
filters when operating a positive- or negative-pressure dust collector.
Pressure drop, typically measured in inches of water column (in w.c.), is a
good indicator of the amount of dust that has collected on the filter media
and, if continually monitored, the condition of the filters.
New filters have the
lowest pressure drop because of the inherent permeability of the media. As the
bags develop a dust cake, some particulate embeds itself into the filter media,
increasing pressure drop accordingly. The filtering of the airstream through
this accumulated dust cake provides high-efficiency collection of fine
particulate. In fact, the highest efficiency a dust collector can offer is just
before the cleaning is initiated. However, high differential pressures can
cause filter media bleed-through or blinding. Therefore, do not to exceed the
manufacturer's recommended operating pressure drop.
3. Ensure cleaning system functions properly — Equipment use a variety of cleaning systems to dislodge accumulated
dust cake from the filter media. Systems include reverse air, shaker or pulse
clean. Regardless of the style of cleaning, it is imperative that this system
function properly at all times. Without an effective cleaning system, dust will
continue to build on the bags. The result will be an increased pressure drop
and reduced volume of ventilation air at the pick-up points. Further, airstream
velocities within the ductwork will decrease and cause dropout of dust in the
ducts. This may choke the entire system and render it ineffective.
4. Watch for visible emissions — This includes any particulate that can be seen discharging from the
exhaust stack. These emissions indicate a breach in a seal or a broken (torn)
filter. In either case, you must find and correct the leak immediately. Not
only will the emission cause a health concern and damage the property outside
the plant, but it may also bring about monetary fines imposed by local, state
and federal environmental agencies. Additionally, fans located downstream of
the collector can be damaged from abrasion or become imbalanced if you don't
correct this condition quickly.
Continually monitor exhaust
from the dust collector. Besides visual inspections, consider incorporating a
broken bag detector into the clean air ductwork. If a bag begins to fail, or
there's a leak in the bag seal, you'll detect the particles that bypass the
media. Typically, these detectors use triboelectric technology. These devices
can be wired to an alarm horn, siren or PLC.
5. Select the right exhaust fan — Dust collection systems require an exhaust fan to accelerate
ventilation air from the point of pick-up, through the ductwork and dust
collector filter media and out the exhaust stack. Fans are selected to
accommodate volume (SCFM) and pressure drop throughout the system. Calculate
the pressure drop by evaluating the static resistance of the dust collector,
ductwork and pick-up points/hoods.
6. Inspect the filter media — This is
the most important item in a dust collector because it accumulates and supports
a dust cake. This dust cake is what provides high filtering efficiencies during
operation. Inspect the clean-air side of the dust collector for leaks and the bags
for tears. If pressure-drop within a dust collector becomes extremely high
relative to historical data, it may be caused by excessive dust cake or
blinding of the filter bags.
Depending on the
application, differential pressure may take a number of hours or even days to develop.
It is essential that you keep filtering velocities low for new filter media.
Reducing the volume decreases the airstream's velocity, thus protecting the bags
from high-velocity impingement of dust. If you expose bags to the fan's full
volume, fine particles may embed themselves into the bags' inner fibers and
begin blinding. This can also reduce the life of the bags by damaging the
fibers of the media. So make sure to season a collector's filter bags.
This is not an
all-inclusive list. Each piece of equipment and application is different, and
each has its own unique components and features. But these simple procedures can
help you monitor and maintain your dust collector's heath, as well as prevent
shutdowns due to inefficiencies, prolong filter life and prevent costly EPA