5 Reasons Why Air Knives Are Safer Than Compressed Air

Blower-driven air knives operate at such low pressure – they’re so safe – that they don’t need an emergency stop button.

That’s one less thing to specify, to have to maintain, to be inspected regularly or to worry about. It makes all the internal ‘politics’ of specifying extra equipment for your production line easier to negotiate (in both senses of the verb).

This simplicity and lower risk ensure it’s easier to comply with the stringent safety requirements outlined in the EU’s Machinery Directive and its equivalent UK legislation.

There’s an old saying in procurement: “Nobody ever got fired for buying Microsoft.” (The original version of this quote, referring to IBM, dates back to the 1970s). Nobody was ever handed a P45 for specifying the safe option.

And that’s precisely what an air knife is – safe, predictable and cost-effective.

Unlike other production line machinery, air knives have no outer moving parts that could trap or injure fingers or hands. The blower’s rotating impeller that creates the air pressure is tucked away safely inside the air knife housing. You’d have to take the machine apart to get to it.

And in some systems, the air blower may not even be in the same room as the plenum (blade) that delivers the airflow. So either way, the impeller is well away from the air knife operator or anyone else in the vicinity.

That’s no reason to be complacent though. At ACI, we take air knife performance and safety very seriously so we’re always looking for new ways to minimise noise and displacement of water or debris (such as breadcrumbs during a food coating process).

Air knife systems such as our premium LNL are fully enclosed to reduce noise levels. There are noise attenuation guards around the EP10A blower, and baffle plates on both the entry and exit points.

Air that is pressurised quickly heats up – and conversely, air that is suddenly depressurised then cools rapidly. In thermodynamics, this is called adiabatic cooling. It explains why the airflow discharged from a compressed air nozzle feels very cold…unpleasantly so.

As you have read, air knives operate at low pressure. So the air inside the blower is not heated up as much as the air inside a compressor. (This is another safety advantage in favour of air knives.)

Consequently, the low-pressure airflow from an air knife plenum is not as cold as compressed air. This is significant – not just for safety – but also because very cold air may not be suitable for your application. This is an important consideration for sectors such as food processing and aerospace.

Air discharged from an air knife blade will be around 30-40°C. That’s about the temperature of bath water.

Air temperature (and how it is affected by altitude) is one of the many factors we consider when creating a customised air delivery solution to suit your exact requirements.