Small But Mighty
In any laboratory clean room, fume cabinets—also known as chemical fume hoods—are a critical line of defence against hazardous airborne contaminants. They protect researchers, technicians, and the wider lab environment from exposure to volatile chemicals, ensuring work is carried out safely and effectively. But even the most advanced chemical fume hood can underperform if not properly maintained. So, how do you know if your system is working as it should? And what early warning signs should you be watching for?
Let’s dive into the subtle (and not-so-subtle) signs that your fume cabinets could be falling short—and how to fix issues before they become serious safety concerns.
1. Unusual Airflow Noises or Visual Disruptions
A properly functioning chemical fume hood should operate with a consistent and relatively quiet airflow. If you notice sudden whistling, buffeting, or vibration noises, that’s a red flag. These sounds can indicate turbulence or inconsistent airflow across the sash opening, both of which may compromise containment. Likewise, if visible smoke or vapour doesn’t draw smoothly into the hood during a smoke test, it’s time to investigate further.
2. Sash Position and Operator Habits
The position of the sash isn’t just about ergonomics—it’s about performance. Fume cabinets are designed to operate efficiently at specific sash heights. Operating the hood with the sash too high can disrupt the airflow balance and reduce face velocity, putting operators at risk. If personnel frequently bypass this guidance, it could be a training issue or a sign the cabinet’s design isn’t supporting best practice.
3. Face Velocity Below Standard
According to Safe Work Australia and AS/NZS 2243.8:2014, face velocity—the speed at which air is drawn into the fume cabinet—should typically sit between 0.5–0.6 m/s. Anything below that threshold may not adequately capture chemical vapours. Routine airflow testing should be performed, and any decline in velocity should be addressed immediately.
4. Poor Containment or Backdrafting
If odours are noticeable outside the hood, or if smoke during a containment test escapes into the room, the fume cabinet is not operating properly. This may be due to obstructions, overcrowding within the hood, poor room airflow, or a failing exhaust system. In a laboratory clean room setting, such failures can lead to cross-contamination—particularly problematic for sensitive or sterile applications.
5. Filter Saturation in Ductless Units
For ductless chemical fume hoods, filter performance is everything. Over time, activated carbon filters become saturated, reducing their effectiveness and allowing chemical vapours to escape. Relying on a time-based change schedule isn’t always sufficient. Instead, use filter saturation indicators or chemical sensors to monitor real-time air quality and performance, especially in high-usage labs.
6. Visible Dust, Residue, or Corrosion
Dust or chemical residue on the interior surfaces of your fume cabinet suggests poor airflow or inadequate cleaning procedures. Corrosion, especially around ducting or filter housing, may indicate chemical build-up from leaks or poor ventilation design. This not only signals a performance issue but could point to wider maintenance or design faults.
7. Outdated Certification or Lack of Testing
All fume cabinets in Australia must be tested and certified regularly under AS/NZS standards. If your unit hasn’t been tested within the last 12 months, or if documentation is incomplete or out of date, it’s a compliance issue. Regular maintenance and calibration by NATA-accredited technicians is essential to ensuring your equipment is up to standard.
Keep Your Fume Cabinets—and Your Team—Safe
Your fume cabinets are not a set-and-forget system. From the smallest benchtop chemical fume hood to the most complex installations in a laboratory clean room, performance issues can develop over time—and often without immediate, visible signs.
Staying proactive through regular certification, operator training, and awareness of warning signs like airflow changes, odours, and sash misuse can help you catch problems early. If you’re unsure whether your system is still compliant or performing at its best, speak to a NATA-accredited testing provider with experience in laboratory clean room environments. At the end of the day, your people, processes, and research deserve the highest level of protection—and that starts with ensuring your fume cabinets are up to standard.