Stop the Lack of Air from Destroying your Plant and your Bottom Line Signs that you have a make-up air problem and what to do about it

January – February 2002

By Claire B. Lang
Industrial Ventilation, Inc.
Greenville, WI

It begins with worker draft complaints and outside plant doors that are hard to open. Soon, you notice excessive dirt and dust accumulations, debris at the threshold of the door, odors that drift from one plant to another, pilot lights that don’t stay lit or back drafting that causes a carbon monoxide hazard not visible to the human eye. It’s subtle at first but, before you are even aware that there is a problem, paint begins chipping and small cracks and rot begin to appear in walls and under wall coverings. Walls in your plant can literally become cold and begin to sweat. Employee absenteeism with colds and sore throats begin and complaints from unhappy workers increase. Finally, as your plant begins to literally gasp for fresh make-up air, your bottom line takes a nosedive.

It may sound a bit far fetched, but it’s not. As exhaust fans compete with each other for available air within a building, attempting to move air that is not there, they pull air from anywhere they can, even sucking it through walls, bringing water from rain and other sources through. “Appropriate air supply is absolutely essential to the bottom line in manufacturing and avoids a serious condition called ‘negative pressure’ within your plant” explains Gerald Auler, the president of Industrial Ventilation, Inc. in Greenville, WI, one of the industry’s foremost practitioners in the design, manufacture and installation of air systems for manufacturing plants. Auler says the signs that your plant has a problem are relatively simple to spot:

  • Dust collection and local exhaust systems are impaired
  • Poor paint finishing due to dust, moisture or fumes
  • Walls have moisture being pulled through
  • Smoke, haze and dust floating in the air
  • When walking through the plant, odors seem to linger
  • Locker room, bathroom and other odors seem to creep through the plant and office
  • People’s clothes smell like the production line
  • Stacks and exhaust fans take up a large portion or your roof
  • Fan motors work harder than they are required to
  • Doors are hard to open or will not shut on their own
  • Cracks under the doors collect leaves, dirt or other debris
  • Shutters on exhaust fans are not 100% open
  • Fume hoods seen to have a downdraft rather than the normal updraft
  • Cold walls
  • Pilot lights go out and the area smells of flue gasses

“You should be able to see from one area of the plant to another without the area being blocked by haze and smoke” Auler explains. “If an area clears when a window or door is opened it is starved for air and you have a make-up air problem.” He advises you to look on the roof of your plant to see if exhaust fans take up a large portion of it. The area of inlet air should be equal to or greater than the area of exhaust air.

It’s best to take a sensible, calculated approach to solving the problem. “First, check to see that proper maintenance procedures are followed on your ventilation system and consult with the original suppliers and manuals to see if your current system can be adjusted to bring performance up”, Auler says. In most states, the Occupational Health and Safety Administration (OSHA) has a free consultation service at where you can get initial advice. Auler further advises to check for experience within your specific industry before hiring a ventilation contractor. “Design-build contractors are the most cost effective because they don’t have to let out projects to subcontrators which costs valuable time and money.” He suggests getting a specific time deadline from contractors and researching a contractors track record. See if the contractor is experienced enough to provide innovative solutions such as retro-fitting existing equipment with upgrades or laying out a long-term, step-by-step plan to bring your company up to air standards.

Don’t let the plant door hit you on your way out. Negative pressure will not only create a condition where outside doors are hard to open and “slam” shut – the condition could be so severe that it eventually leaves you literally, out in the cold.

January – February 2002