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Optimal air quality results from solid planning

6 questions to ask before equipping your plant

Air quality systems’ designs should be blueprinted just like any other facility infrastructure.

Carpenters are well-acquainted with the old saw “measure twice, cut once.” It’s an adage that applies to air quality system design as well. Designing an effective system doesn’t have to be trial and error. To get the best results and avoid costly mistakes, you would do well to spend sufficient time evaluating and planning.

Evaluating the Current State

Different types of welding and manufacturing processes result in different indoor air quality issues. The makeup of the particulates that workers are exposed to, their quantity, and the way they travel through a plant determine exposure risks. It’s important for manufacturers to first understand current conditions before beginning a system design.

Six questions to ask are:

1. What processes am I using? The composition and volume of the fumes created vary depending on whether you are doing manual welding, robotic welding, or some other type of industrial process such as cutting or grinding.

2. What is the composition of the particulates? How fumes impact worker health and safety depends on the fumes’ chemical makeup. Weld fumes can contain many toxic elements and compounds, including manganese, hexavalent chromium, nickel, copper, vanadium, molybdenum, zinc, and beryllium (see Figure 1). Each of these carries its own health risks and regulatory guidelines for exposure. The exact nature of the fumes produced depends on the base materials and consumables you use in your welding process, as well as any coatings or lubricants that are on the material. Characterizing fumes allows you to understand exposure and safety risks such as combustibility.

3. What is the volume of particulates created? How much dust or fumes you generate depends on the process you are using. Robotic welding tends to create more fumes than manual welding. Cutting and grinding applications generate a much larger volume of particulates than welding. Continuous processes generate a higher volume over time than those that are sporadic.

4. Where are fumes generated, and where do they end up? Air quality can vary widely across a plant. It tends to be worst at the point of generation, such as your welding or grinding stations. However, dust and weld fumes can travel far from their origin and can affect workers who are not even involved in those operations.

Typically, fumes rise because of the thermal currents produced during the processes. Then air currents can carry particulates to other places in the plant where they will re-enter the “breathing zone” as they cool and ultimately settle on surfaces. That particulate can be toxic.

5. What are the airflow patterns in my facility? Every facility has its own unique airflow patterns that influence how weld fumes propagate throughout the plant, where they linger, where they end up. These patterns can create “microclimates” in different parts of the facility. The type and location of existing ventilation and HVAC equipment, locations of windows and doors, equipment position, temperature variations, and other factors influence these patterns. To be most efficient and effective, your remedy should be designed to work with your airflow patterns, not against them.

6. Which mitigation systems do I have in place already, and how are they working? Do you have source-capture systems in place? Roof ventilation? How do these systems influence airflow and air quality at different points in the building? Obviously, when designing a new air quality system, you should consider the condition and limitations of any existing equipment.

Figure 1
Weld fumes can contain many toxic elements and compounds, including manganese, hexavalent chromium, nickel, copper, vanadium, molybdenum, zinc, and beryllium. Photo at left was taken before an air quality system was designed and implemented.

Testing the building’s air quality will give systems engineers quantitative information about its current state so they can use a scientific approach to systems design instead of guesswork. It’s important to test the air at various key points in the facility, not just near the welding, grinding, and cutting stations.

Setting Your Goal

Once you have a firm grasp on your current air quality situation, you can start thinking about your air quality goals. Of course, you will want to make sure you are meeting all applicable national, state, and local regulations for worker health, safety, and environmental compliance to avoid getting expensive penalties and fines. Many forward-thinking companies are going beyond Occupational Safety and Health Administration (OSHA) minimums and setting their own more stringent air quality standards or using the more stringent American Conference of Governmental Industrial Hygienists (ACGIH) guidelines for particulate exposure levels. As research clarifies exposure risks, regulatory bodies are moving toward stricter limits. Preparing to meet these targets now will ensure that your facility will be prepared to meet changing regulations in the future.

Using Computer Modeling to Design a Better Air Quality System

An optimal way to proceed so that your plan takes everything into consideration and meets your goals is to use computer modeling (see Figure 2). Sophisticated computer models help you understand how different variables interact with each other so that you can design the most effective and efficient system for your plant.

The model must account for:

  • The precise interior measurements of the plant, including type and placement of all equipment, as well as window, door, and wall configurations that affect air movement.
  • Current data about the existing air quality state at different points in the facility.
  • Analysis of existing airflow patterns in the building.

Once the model is built, you can use it to virtually design and try different air quality technologies. This allows you to predict the impact different system designs have on the ultimate air quality outcomes. Computer modeling saves considerable time and money. You can test different placements of collectors and ductwork, compare the results of different types of equipment, and determine which options will best meet the facility’s air quality goals.

Effective virtual design programs must be based on accurate mathematical modeling of the different variables that affect air quality and how they all work together. If the underlying mathematics is not correct, the software will not be able to provide reliable outcome predictions. Models must be able to accurately and reliably determine how changing different variables will change the results, such as adding a collector, changing locations of fans or blowers, changing ductwork, or adding room dividers.

Done right, computer modeling allows you to avoid over- or underengineering your air quality solution. Often, companies install a few collectors and then, if they are not getting the results they wanted, add more until the air is clean enough. With modeling, you can optimize the placement of source- and ambient-capture equipment to make sure you are getting the most use out of each piece of equipment for the most efficient and cost-effective system.

Every manufacturing plant is unique. The best air quality system will be the one that is designed with your goals and facility in mind. A little advance planning will go a long way toward ensuring your ultimate satisfaction with your air quality system.

Good Air Quality’s Broad Effects

“Soft” benefits of implementing an air quality system may include:

Figure 2
Sophisticated computer models look at multiple variables to determine the most efficient strategy for air quality improvement. The top model depicts optimal airflow in a plant. The middle thermal model is the “before” diagram, and the diagram on the bottom is the redesigned air quality pattern

• Productivity. Better air quality is linked to higher productivity and fewer errors, according to facilitiesnet.com. It also can reduce absenteeism. Conversely, poor indoor air quality has been estimated to cause six additional lost workdays per year for every 10 employees.

• Worker Retention, Satisfaction. A pleasant working environment can go a long way toward improving workers’ attitudes about their jobs. Clean air tells employees that you care about their health and well-being, which is bound to increase job satisfaction and loyalty.

• Recruiting. Skilled manufacturing workers are in high demand. The Manufacturing Institute and Deloitte anticipate a shortage of 2 million skilled workers by 2025. Increasingly, a healthy work environment—including good air quality—is an important factor in attracting the best talent.