If your air quality isn’t quite where you want it to be, there are plenty of possible solutions to choose from: ambient push-pull systems, standalone dust collectors, and source capture options in all shapes and sizes. But how do you know which combination of equipment is best for your facility?
For small shops with industry-standard welding, cutting or grinding equipment, the selection may be easy. Experienced air-quality engineers can apply simple rules of thumb to determine how many dust collectors are needed and where they should be placed. But for larger or more complicated operations, a more scientific approach may be called for. Sophisticated computer modeling programs can help system engineers design the most effective and efficient solution for an individual facility.
By examining all the variables and running different scenarios, these models can help business owners find the most cost-effective solution to meet air-quality goals.
Many variables impact the ultimate efficacy of an air-quality remedy, including the type of processes being run, the location of fume-generating equipment and existing airflow patterns in the building. The larger and more complex the operation, the more variables come into play and the harder it is to predict the impact of a specific solution.
That’s where computer modeling comes in. Using sophisticated analytical engines, system designers can build a mathematical model of a facility that allows them to see how all of the variables interact. Then, they can virtually try out potential mitigation solutions and more accurately predict the impact of different system designs on air-quality outcomes.
Computer modeling allows a fabricator to avoid over- or under-engineering an air-quality solution to get the most effective system for the money. With modeling, it’s possible to optimize placement of source and ambient capture equipment to get the most utility out of each piece.
Instead of simply throwing “more and better” dust collectors at the problem, engineers can now analyze dozens of potential remedy options in virtual space. For example, facilities may be able to minimize the number of dust collection units they need to buy by taking measures such as changing locations of fans or blowers, repositioning equipment or ductwork, or adding room dividers. Engineers can analyze these options and test the impact of different equipment options and placements to find the most cost-effective design to meet the company’s goals.
To build an accurate predictive computer model, engineers need to take into account:
- The current particulate levels throughout the facility
- The facility layout and existing airflow patterns
- The company’s air-quality goals and objectives
Establishing the baseline
Before a facility can build a computer model, it’s important to establish a baseline of the current state. That means gathering quantitative readings of particulate levels throughout a facility. Dust concentration meters can give a business owner the data that’s needed.
It’s not enough, however, to just take readings near the dust-producing activities. In order to understand how dust and fumes propagate and gather throughout a facility, it’s necessary to measure particulate concentrations far from the source, especially in aisles, workstations and other places where people gather. To get the most accurate results, take readings in a grid pattern throughout the facility. Meters should be set up in the “breathing zone,” about 5 ft. off the ground.
If a fabricator’s processes are continuous and regular over time, a few snapshot readings in each location may be enough. However, if processes are irregular (such as manual welding or cutting operations that stop and start frequently, or cyclical processes that produce more fumes at some times than at others), meters can be set to take incremental readings over a longer time period. These meters can provide peak readings and a time-weighted average (TWA) over the course of an 8-hour shift.
If any welding processes produce toxic particulates such as hexavalent chromium, beryllium or manganese, it’s also recommended to collect particulate samples for lab analysis to get an accurate characterization of the chemical makeup of the dust. It’s entirely possible to be within regulations for overall particulate exposure but out of regulations for exposure to a particular element or compound of concern. If processes, base materials and consumables are well understood, it may be possible to estimate these levels from the total particulate levels. However, lab analysis gives the most accurate results.
Mapping airflow patterns
Every facility has it’s own unique airflow patterns, which influence how weld fumes propagate through the facility, where they end up and where they linger. The dust concentration meter readings at different locations provide important data. But designing an effective remedy also requires a more in-depth evaluation of the existing airflow patterns.
Airflow is influenced by many factors, including the type and location of existing ventilation and HVAC equipment; the location of building elements such as walls, windows and doors; temperature variations throughout the building; and thermal or wind currents generated by the equipment itself. These elements set up natural air currents throughout the building that can carry dust and fumes far from their original source.
To be efficient and effective, an air-quality remedy should be designed to work with the existing airflow patterns, not against them. Building an accurate computer model requires mapping out the unique airflow patterns throughout the facility. The model needs to take into account the precise interior measurements of the facility, including the type and placement of all equipment as well as window, door and wall configurations that impact air movement.
Before anyone can begin designing a solution, it’s key to define the ultimate air-quality goals. Do you simply want to make sure that you are meeting all national and federal regulations? Or do you want to establish stricter internal guidelines for indoor air quality (IAQ)?
If the state of existing air quality is poor, it’s natural to start thinking in terms of simply bringing a facility into compliance with OSHA and EPA regulations. However, as more research is conducted on the potential health impacts of weld fumes and other toxic particulates, these regulations are likely to be tightened. Forward-thinking companies are preparing themselves for the future by instituting their own tighter IAQ guidelines now.
Many companies are turning to the American Conference of Governmental Industrial Hygienists (ACGIH) for guidance on particulate exposure levels. These voluntary standards tend to be more stringent than current OSHA standards, both for total particulate levels and for exposure limits for individual elements and compounds. ACGIH standards have been adopted as best practice by a number of large global manufacturing companies.
Some companies are going beyond even these standards and setting their own internal guidelines for IAQ, often motivated by concerns related to productivity, recruiting and retention. Increasingly, work environment – including air quality – is an important factor in attracting and retaining the best talent.
With the U.S. manufacturing sector anticipating a shortage of two million skilled workers by 2025, companies wanting to set themselves apart are taking steps to make their workplaces more comfortable and attractive to current and prospective employees. Clean air tells employees that their employer cares about their health and wellbeing, increasing job satisfaction and loyalty. Better air quality is also linked to higher productivity, fewer manufacturing errors and reduced absenteeism. Many companies are finding that these benefits are well worth an additional investment in air quality.
The future of air-quality design
No matter what a business’s goals are, there is an air-quality solution that can help achieve them. Designing the best solution requires carefully balancing desired outcomes against cost, time and space considerations. Computer modeling allows a business owner to more easily see the tradeoffs.
However, the model is only as good as its underlying algorithms and inputs. If a business owner is interested in computer modeling, it’s important to work with system engineers who understand how the model works, what kind of data it needs and how to collect that data.
Effective virtual design programs must be based on accurate mathematical modeling of the variables that impact air quality and how they all work together. It also depends on having complete and accurate data to input into the program. If the underlying mathematics are not correct, the software will not provide reliable predictions of outcomes. RoboVent’s VentMapping program was based on four years of research and development to ensure that the resulting models would be highly accurate and predictive.
With tightening air-quality regulations and increased pressure for cost control, it’s more important than ever for manufacturing companies to select the remedy that provides the best outcomes for the money. Computer modeling can help fabricators find it.