What happens when smoke starts to fill a building? It’s not the flames that usually cause the most harm – it’s the smoke. Thick, toxic, disorienting. This is where AOV systems come in. They do one crucial job: they help keep people alive when every second counts.
Let’s break down what AOV systems actually are, how they work, and why they’re such a critical part of building safety.
What is an AOV System?
AOV stands for Automatic Opening Vent. It’s a life-saving component of a building’s fire safety strategy. When a fire breaks out and smoke is detected, these vents automatically open to let smoke and heat escape. The goal is to keep escape routes – stairwells, corridors, lobbies – clearer for longer, so people can evacuate safely and firefighters can get in without being overwhelmed by smoke.
The system is mechanical, but intelligent. It links up with fire detection systems and responds instantly, without waiting for human intervention. Depending on the building design, Surespan AOVs can be fitted into walls, ceilings, windows, or roofs.
Why Smoke Control is Vital
In a fire, smoke spreads fast. It can block exits, reduce visibility, and create a highly toxic environment. Most fatalities in fires aren’t caused by flames – they’re the result of inhaling smoke. This is especially dangerous in multi-storey buildings where people need to move quickly through shared spaces.
AOV systems help:
- Protect escape routes by removing smoke, visibility is maintained and routes stay usable
- Reduce toxic exposure by venting harmful gases out of the building
- Prevent flashovers by releasing heat and lowering internal temperatures
- Assist fire crews by making it safer and easier for them to enter and control the fire
In short, they give people a better chance of getting out safely, and give emergency services a better chance of doing their job effectively.
How AOV Systems Work in Practice
When a fire starts and smoke is detected by alarms or sensors, the AOV system springs into action. The exact sequence depends on how the building is set up, but generally, it works like this:
- Detection – A smoke detector triggers the system.
- Signal sent – The control panel receives the signal and decides which vents need to open.
- Vents open – Actuators (small motor mechanisms) automatically open the right vents.
- Airflow created – As smoke is drawn out, cooler air enters through other openings, helping push smoke upwards and out.
It’s a bit like creating a controlled draft. The key is to get smoke moving in the right direction and out of the building. Some systems also include manual overrides so fire crews can control the vents as needed.
Where You’ll Find AOVs
These systems are most commonly used in buildings with shared corridors and stairwells. Think residential flats, hotels, office buildings, and even some schools or hospitals. Anywhere that people need to evacuate through common areas, AOVs are likely part of the fire strategy.
They’re especially important in buildings that rely on a ‘stay put’ fire policy, where not everyone is expected to evacuate immediately. In these cases, keeping communal areas clear of smoke becomes even more critical.
Natural vs Mechanical Smoke Ventilation
There are two main types of AOV systems:
Natural smoke ventilation uses openings in the building (like roof vents or windows) to let smoke out using natural airflow and pressure differences.
Mechanical smoke ventilation uses fans and ductwork to extract smoke more forcefully.
Each type has its own advantages. Natural systems are simpler and use fewer moving parts, so they tend to be more reliable and easier to maintain. Mechanical systems, on the other hand, offer more control and are better for taller or more complex buildings where airflow needs to be actively managed.
The choice depends on the building’s design, size, and fire safety requirements. But both systems aim to achieve the same result – smoke-free escape routes and better visibility during evacuation.
Maintenance Isn’t Optional
Once installed, AOV systems can’t just be forgotten about. They’re part of the fire safety system and need to be maintained regularly. This means:
- Routine testing to check sensors, actuators, and control panels
- Cleaning vents to make sure there’s no debris or blockages
- Ensuring power supplies (especially for systems with battery back-up) are fully functional
Regular checks aren’t just about ticking boxes. If a vent fails to open in an emergency, the consequences can be fatal. That’s why regulations require routine inspections and testing – usually every six months, and more frequently in high-risk buildings.
How AOVs Fit Into the Bigger Picture
AOVs aren’t standalone systems. They’re part of a much broader fire strategy that includes alarms, sprinklers, fire doors, evacuation plans, and passive fire protection like compartmentation.
In fact, they often work with other systems. For example, they may be triggered by the same detectors that sound the fire alarm. Or, they may interact with fire doors or dampers to create a managed smoke path. Getting this integration right is essential for the system to do its job properly.
Fire safety engineers usually design these systems as part of a whole-building fire plan, making sure everything works together in the right sequence. That way, if a fire breaks out, the building responds in a coordinated and reliable way.
The Bottom Line on AOVs
When smoke is the biggest threat in a fire, you need a system that can deal with it automatically, immediately, and reliably. That’s what AOV systems do.
They may not be as visible as alarms or sprinklers, but they are just as important. By removing smoke from escape routes, they buy precious time for people to get out, for help to get in, and for damage to be contained.
