Ventilation systems are crucial in chemical plants, ensuring clean air and safe working conditions. However, they can also be very noisy, which can affect employee health and productivity. Too much noise can cause hearing problems, stress, and make it hard to focus. In this blog post, we’ll discuss why controlling noise is important, different ways to reduce it, and smart design choices to make your facility quieter.
If you want expert help in designing ventilation system noise control for your facility, reach out to Eldridge – we have the experience and technical know-how to make a real difference.
Noise Levels of Common Ventilation System Components
Understanding the noise contribution of individual components is crucial when designing and troubleshooting ventilation systems in chemical production facilities. Here are some common components and their typical associated noise levels:
Fans: Arguably the most prominent noise source. Centrifugal fans generally produce a broad-band noise with dominant frequencies related to blade passage frequency and motor speed. Depending on size, design, and operating conditions, noise levels can range from 75 dBA to over 100 dBA. Axial fans, often used for high airflow requirements, can also generate substantial noise, typically in the 80-95 dBA range.
Motors: Electric motors driving fans and other equipment produce noise primarily from electromagnetic forces and bearing friction. Noise levels usually fall within the 70-90 dBA range, influenced by motor size, speed, and load.
Air Handling Units (AHUs): These central components house fans, filters, heating/cooling coils, and dampers, collectively contributing to noise generation. AHU noise levels vary widely depending on the configuration and internal components, typically ranging from 75 dBA to 90 dBA.
Ductwork: While not a primary noise source, ducts can transmit and radiate noise generated by fans and other equipment. Airflow turbulence within ducts can also create additional noise. Duct-borne noise levels depend on factors like airflow velocity, duct size, material, and presence of bends or obstructions.
Dampers and Louvers: These airflow control devices can generate noise due to flow turbulence and mechanical vibration. Noise levels typically range from 60 dBA to 80 dBA, influenced by damper type, size, and operating position.
Terminal Devices (Diffusers, Grilles): While relatively quieter, terminal devices can contribute to overall noise levels, especially in close proximity to occupants. Noise levels typically range from 30 dBA to 50 dBA, depending on design, airflow velocity, and throw pattern.
These are approximate noise levels, and actual values can vary significantly based on your specific equipment and system configuration.
Health and Safety Impact of Long-Term Noise Exposure
In chemical plants, loud ventilation systems can be a big problem. Over time, too much noise can seriously damage employees’ hearing. This is called noise-induced hearing loss (NIHL), and it is a major workplace hazard. Studies show that workers in noisy industries are much more likely to develop hearing problems than those in quieter jobs. In fact, the National Institute for Occupational Safety and Health estimates that around 22 million U.S. workers are exposed to hazardous noise levels each year.
Long-term exposure to loud noises is a major cause of hearing loss. Experts agree that any sound above 85 decibels can be harmful if you’re exposed to it for long periods. To put that in perspective, a busy city street is around 80 decibels, and a lawnmower is around 90. In a chemical plant, ventilation systems, pumps, and other machinery can easily reach these dangerous levels. It is also not just about how loud the noise is; it’s also about how long someone is exposed to it. Even lower levels, like 75 decibels, can cause damage for employees hearing these sounds for 8 hours a day, every day.
Hearing loss doesn’t happen overnight, it builds up gradually. However, if the noise exposure continues, the damage can become permanent. Besides hearing loss, noise can also cause other health problems. It can increase stress levels, raise blood pressure, and even disrupt sleep, which can impact employees’ ability to focus and concentrate at work. This can impact overall productivity as well as safety. In addition, if employees are not able to hear warning signals or alarms, they are more likely to get injured.
Noise Control Options for Ventilation Systems
Ventilation systems often generate significant noise due to the powerful fans, motors, and airflow involved. To mitigate this, we can strategically implement or recommend various noise control measures categorized into source control, path control, and receiver control.
Source Control
- Fan Selection: Opting for quieter fans with lower sound power levels or employing variable speed drives to reduce fan speed when full capacity isn’t necessary.
- Vibration Isolation: Implementing vibration isolators (spring mounts, rubber pads) between the fan/motor assembly and its supporting structure to minimize vibration transmission and subsequent noise radiation.
- Equipment Maintenance: Regularly inspecting and maintaining fans, motors, and bearings to ensure they’re operating optimally and not generating excessive noise due to wear or imbalance.
Path Control
- Silencers: Installing silencers (absorptive, reactive, or combination) in the ductwork to attenuate noise propagation. The selection of silencer type and size depends on the frequency spectrum of the noise and desired insertion loss.
- Duct Lining: Applying sound-absorbing materials (fiberglass, mineral wool) to the interior of ductwork to dampen sound transmission within the system.
- Sound Enclosures: Enclosing noisy equipment (fans, compressors) within soundproof enclosures constructed from dense materials and incorporating sound-absorbing linings.
- Lagging: Wrapping pipes and ducts with sound-absorbing materials to reduce noise radiation from their surfaces.
Receiver Control
- Hearing Protection: Providing workers with appropriate hearing protection devices (earplugs, earmuffs) to reduce noise exposure at their ears.
- Acoustic Barriers: Strategically placing acoustic barriers (panels, walls) between noise sources and personnel to create a “shadow zone” of reduced noise levels.
- Soundproof Control Rooms: Designing control rooms with soundproofing elements (double-glazed windows, sound-isolating doors, acoustic ceiling tiles) to provide a quiet workspace.
- Worker Rotation: Limiting the duration of worker exposure to high noise levels by implementing job rotation schemes.
Additional Considerations
- Aerodynamic Noise: Addressing airflow-related noise through proper duct design (smooth bends, gradual transitions), airflow control devices (dampers, turning vanes), and selecting appropriate air velocities.
- Structural-Borne Noise: Minimizing noise transmission through building structures by using resilient mounts, flexible connections, and vibration-damping materials.
Implementing a comprehensive ventilation system noise control strategy requires careful analysis of the noise sources, transmission paths, and receiver locations within your facility.
Experienced Design for Ventilation System Noise Control
Don’t let noise disrupt your chemical production facility. Eldridge offers expert technical assessments and experienced design solutions to improve the noise control of your ventilation system. Our team will analyze your current setup, identify noise sources, and implement tailored strategies to create a quieter, safer, and more productive work environment. Contact us today to book an initial consultation.