Explore new options to bring cleaner air to the plant floor

Indoor air quality is an increasingly important responsibility for plant managers. Fundamental concerns include fiscal responsibilities for energy conservation and waste minimization, and additional duties arise from the need to comply with workplace heath and safety standards.
By Mike Harris, Air Quality Engineering Inc. January 1, 2009

Indoor air quality is an increasingly important responsibility for plant managers. Fundamental concerns include fiscal responsibilities for energy conservation and waste minimization, and additional duties arise from the need to comply with workplace heath and safety standards.

Concerns over clean air in the workplace are well founded. Additionally, the energy costs of operating HVAC systems at less than optimum air flows due to dirty and expensive-to-replace filters continue to rise.

Choosing air cleaning solutions

These costs can be minimized by using air cleaning equipment at the source of the airborne contaminant and selecting an air cleaning technology that minimizes filter replacement costs and environmental costs. Consider the following factors when narrowing the choices for air cleaning equipment:

  • Type of contaminant generated

  • Concentration of the contaminant

  • Airflow to provide desired results

  • Ambient vs. source capture collection

  • Filtration/adsorption efficiency

  • Maintenance preference

  • Start-up costs and operating expenses.

    • One of the most common shop air contaminants is coolant mist. Control of this airborne contaminant is frequently associated with high maintenance costs due to the rapidity with which the filters tend to clog. Failure to control coolant mist in the plant air leads to elevated HVAC maintenance costs, slippery floors and increased employee health-related complaints.

      Using electrostatic precipitators

      A viable solution to consider for these circumstances is electrostatic precipitation (ESP). Two-stage electrostatic precipitators were invented by Gaylord Penney in the 1930s, and since that time they have been used extensively in industry for particulate removal down to 0.01 microns. With today’s emphasis on green manufacturing, the advantage of this well-known technique for controlling very fine contaminants is almost self-evident: there are no filters to replace.

      A novel way of applying ESP to coolant mist from CNCs has been recently developed. The new approach entails installing complete, self-contained systems rather than the old, traditional method of hanging big boxes from the ceiling and running ducts to each CNC. Self-contained systems can be implemented very quickly and facilitate easy modifications to manufacturing cells without the need for re-routing elaborate overhead duct systems.

      Also, only the systems for the CNCs in operation have to be drawing power. Vertical airflow designed into these machine-mounted systems allows the coolant to drain directly back into the CNC, expanding cleaning intervals to months.

      Modern machining technology requires the use of coolants for longer tool life, closer tolerances and superior surface finishes. These coolants create mists and smoke that are no longer tolerated in leading shops. Coolant is now being applied in small diameter, high-pressure streams rather than just flooding the tool with coolant.

      Keeping coolant mist and welding fume out of shop air reduces HVAC maintenance costs, regulatory liabilities and complaints.

      Author Information
      Mike Harris is a certified industrial hygienist and consultant with Hamlin & Harris Inc., Baton Rouge, LA.