Asphalt Pavement Magazine – May/June 2020 • 53

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By Bill Dempsey, P.E., Lakeside Industries Inc.

Baghouse Do’s and Don’ts

If you see visible emissions, as in this photo, your plant’s baghouse inspection is long overdue.

Baghouses became the prevalent dust collection system for asphalt plant facilities in the 1970s. There are different makes and models of baghouses, but the same basic principles of proper operation, maintenance, and inspection apply at every plant site.

Operation BasicsProper operation of the baghouse is important to help

ensure plant efficiency, emissions compliance, and safety. Some basic principles of baghouse operation we should always DO are:• Break in new bags by “caking” the bags.• Run within the manufacturer’s suggested pressure drop

readings. Too low a reading indicates a leak or no “cake” on the bags, which can lead to accelerated bag wear. Too high a reading and the bags may be “mudded” or plugged, which can starve the dryer of air.

• Operate with the baghouse exit exhaust temperature above the dew point. This will prevent the mudding of bags and premature corrosion on the baghouse structure.

• Always run the baghouse fan for the burner purge cycle and heat up the baghouse before introducing aggregate

to the dryer. The exit exhaust temp should be above the dew point.When operating the asphalt plant, we want to avoid

baghouse practices that will negatively impact safety, emissions, and the plant’s ability to run. That said, DON’T:• Leave dust in the baghouse when shutting down for the

evening since the dust could consolidate and make the dust system inoperable.

• Ignore visible emissions.• Overheat the inlet side of the baghouse.

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54 • View past issues online at www.naylornetwork.com/nap-nxt

MEMBER-TO-MEMBER

This publication is designed to provide information of interest to the asphalt pavement industry and is not to be considered a publication of standards or regulations.

ReferencesBrock, J.D., Brown, J., and Fricks, G. (rev. 2018). BAGHOUSE FINES AND DUST CONTROL OPTIONS (Technical Paper T-121). Astec Inc., Chattanooga, Tennessee.

Kandhal, P.S. (1999). Evaluation of Baghouse Fines for Hot Mix Asphalt (IS 127). National Asphalt Pavement Association, Lanham, MD.

Gunkel, K. O’C. (1986). THE FUNDAMENTALS OF THE OPERATION AND MAINTENANCE OF THE EXHAUST GAS SYSTEM IN A HOT MIX ASPHALT FACILITY (IS-52). National Asphalt Pavement Association. Lanham, MD.

NAPA (1999) Lockout/tagout Plan Guidance (HS-12). National Asphalt Pavement Association. Lanham, MD.

This is an example of good, clean baghouse operations.

Inspection and Maintenance Basics

In addition to properly operating the baghouse, we also need to inspect and maintain the asphalt plant’s baghouse. Inspection and maintenance will help ensure proper operation, equipment longevity, breakdown avoidance, and safety. Basic principles of baghouse inspection and maintenance we should always DO are:• Lock out/tag out baghouse power when performing

inspection and maintenance. • Wear the proper PPE and follow company procedures

when performing inspection and maintenance.• Check for leaks at baghouse access points, duct

work, and the baghouse structure itself.• Clean air lines on pressure drop gauges to ensure

accurate pressure readings.• Inspect clean side of baghouse whenever visible

emissions are present, or monthly.• Perform scheduled dye tests or some other leak

detection of the baghouse.

As part of proper inspection and maintenance of the asphalt plant’s baghouse, we want to ensure that we DON’T:• Let dust build up in exhaust ductwork. The build-up

of dust pinches air flow and increases air velocity, which can lead to ductwork wear.

• Use damaged cages when replacing bags. Damaged cages can accelerate bag wear.

• Ignore fan vibration, since this often indicates at least one of the following: fan wear, bad bearings, and/or loose drive belts. AP

ImpactsThe baghouse on an asphalt plant directly relates to the efficiency of the asphalt plant. Understanding proper operation and maintenance of a filter

baghouse system will keep your plant running at a lower cost and higher production rate.

Overheating could cause a baghouse fire. Proper employee training, PPE, best practices, and following the manufacturer’s instructions are key to safe

baghouse operations and inspections.

Visible emissions likely indicate bag failure or leakage. Reducing material losses reduces the consumption of natural resources.

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