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Maintenance and Inspections

Schust provides customers with the most comprehensive preventative maintenance and inspection services to keep air pollution control (APC) systems running as they are intended.  Customers trust Schust because with over 30 years of experience, they know services are performed by knowledgeable technicians.

With our extensive technical and application experience, Schust provides world-class turnkey services you can’t find anywhere else.  Your APC system is thoroughly inspected and if any repairs are needed, Schust can also supply the parts and installation per the final written report.  Preventative maintenance and inspection services can be scheduled to fit your time frame.

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Request a preventative maintenance and inspection service appointment today.

A Preventative Maintenance Inspection Typically Includes:

  • Conduct system air volume measurements and calculations to determine operating performance.
  • Inspect collector discharge hopper, augers, and rotary valves.
  • Check Photohelic and Magnehelic pressure gauges for proper zero function. Re-set, as needed.
  • Verify and record pressure drop across the filters.
  • Measure and record fan inlet static and RPM.
  • Visual inspection on the general condition of the system(s).
  • Ultraviolet leak inspection to locate any leaking filter media.
  • Visual inspection of tube sheets, venturis, and blowpipes.
  • Inspect cleaning system, including pulse valves, solenoid valves, compressed air pressure, and timer settings.
  • Inspect fans including housings, bearings, and drives.
  • Inspect access door seals for leaks.
  • OSHA Confined Space Entry program, air monitoring equipment, and attendant.
  • A written report of each inspection including the following information:
    • Current physical condition of collector(s) and system components.
    • Tubesheet layout drawings indicating location of repaired or defective pulse valves, blowpipes, leaking filter media, and venturies on all baghouse units.
    • Tracking of the system air volume, static and velocity pressure, filter pressure drop, and current test data.
    • A list of recommended repairs.

Hood lacks suction (airborne emissions escaping the existing hood)

This is usually caused by poorly designed hood and/or insufficient airflow in the system. Excessive cross-draft may also reduce the efficiency of a canopy-style hooding.

For a good capture efficiency, the hood shall be designed to achieve the appropriate capture velocity. The capture velocity (ranges from 50 to 2,000 ft/min) is determined based on the type of contaminant and how it is released into the surrounding air. If the contaminant is released at high initial velocity, for example grinding and shake-out, a high capture velocity would be needed to maintain control of the contaminant until it reaches the hood.

Additionally, the design of canopy hooding for hot processes, for example metal pouring and melting furnace, shall take into consideration the effects of thermal draft. This usually means oversizing the hood to account for the increasing air column diameter as it rises from the hot source.

Insufficient airflow in the ductwork may be caused by poor system air balance, excessive static pressure drop in the system, inapt exhaust fans, or issues with the dust collection filter cleaning system.

Visible particulate emissions at exhaust stack

Such condition is usually contributed to the diminishing efficiency of the air cleaning device and it shall be addressed immediately as required by the operating air permit at the plant.

In a dry collector such as a baghouse, visible particulate emissions at the exhaust stack is typically caused by bag/cartridge failure due to (not in any particular order):

  • Normal wear (the end of bag life)
  • Filter material and/or installation defects
  • Other rapid failure modes caused by excessive cleaning frequency or high entry velocity at the collector inlet (known as “can velocity”). Such rapid failure modes can be prevented by implementing “clean-on-demand” and a better inlet distribution baffle.

In the case of cyclone and wet scrubber, the condition can be contributed to (not in any particular order):

  • Decreasing filtering efficiency due to internal mechanical wear caused by abrasion
  • Various abnormal operating conditions such as a higher than normal dust loading in the incoming gas stream
  • Air cleaning device does not match its intended application.

Short filter bag life (high ΔP across the collector)

Although the effect of short filter bag life can be readily noticeable from the rapid rise in the pressure drop across the collector, the cause of such condition can be difficult to diagnose and remedy.

The life of filter varies quite significantly depending on:

  • Material (e.g. fiberglass, polyester, Nomex)
  • Construction (e.g. dual-density, spun/spun)
  • Additional fabric treatments (e.g. Teflon)
  • Field application factors (e.g. grain loading, particulate abrasiveness, temperature, humidity, etc.)
  • The effectiveness of the filter cleaning mechanism

A systematic troubleshooting approach needs to first ensure that the filter cleaning mechanism is operating as intended. This includes checking for proper timing, leaky or plugged blow pipes, correct reversed air volume/pressure, as applicable.

Condensation

Condensation in an air pollution control system most often occurs during cold winter months. It takes place when the warmer gas stream from the process is cooled past its dew point temperature upon contact with the colder duct and equipment surfaces.

In a dry collector, condensation can cause severe blinding and premature bag failure, in addition to bridging in the hopper. Provisions such as insulation, operating at an elevated temperature must be incorporated when there is a potential for condensation in the system.

Excessive noise and vibration at the fan

All fans generate some noise and vibration. It is only when they reach certain amplitude that we consider them “bad” or excessive. Although it is difficult to find the source, the solution to the noise and vibration problems is often obvious.

Some of the more common sources of abnormal noise are (not in any particular order):

  • Fan wheel unbalance
  • Failing, misaligned, or contaminated bearings
  • Rotating components rubbing on stationary parts
  • Belt slipping
  • Operation in surge or stall

Some of the more common sources of excessive vibration are (not in any particular order):

  • Misaligned sheaves
  • V-belt drive deterioration
  • Bearing deterioration
  • Loosening of hardware on the fan and support structure
  • Fan wheel imbalance
  • Material buildup on the fan blade

Complete filter change-out service:

  • Supply of the replacement filters
  • Removal of old filters and staging for disposal
  • Cleaning of the filter mounting mechanism and/or tube sheet
  • Installation of new filters
  • Ultraviolet leak testing using fluorescent indicator

Replacement Worn Duct & Fittings

  • Standard elbows
  • Flat back elbows
  • Ducting
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