Can I Retrofit An Air Knife? Will It Fit My Line?

Why Retrofitting Air Knives Makes Good Sense

Most definitely, “yes” – you can retrofit an air knife. In fact, most air knives tend to be retrofitted to existing production lines. However, sometimes they are installed on brand-new lines from day one.

Air knives tend to be added to existing lines to deal with specific technical issues that have arisen – usually relating to moisture, static or quality control. Industry relies on air knives to:

enhance product quality and consistency
cut drying times – increasing line speeds, boosting output efficiently and cost-effectively
slash energy bills by reducing dependence on costly compressed air.

Is My Production Line Suitable For A Retrofitted Air Knife System?

Today’s new generation of ACI air knives includes advanced features to ensure they fit most production lines. There are three main considerations that will determine how well an air knife system will integrate with your line:

space availability
power capacity
noise constraints.

Certain sectors – such as food and beverage – are particularly well suited to retrofitted air knives. These systems are used to:

remove surface contaminants and keep food clean
blow off excess enrobing coatings (such as batter or chocolate) to improve product appearance and reduce waste.

Breweries specify air knives to dry cans and bottles to:

stop transgranular stress corrosion – ensuring cans do not burst open and damage packaging and other products
prevent coding and labelling issues – ensuring legal compliance and good product aesthetics.

Automotive plants specify retrofit air knife systems for drying and deionisation – to help provide the perfect finish for car and truck bodies, engine components, bumpers, internal trim, rubber and plastic extrusions.

In all these sectors, there are generally fewer variables, so projects can be delivered more quickly.

See the full range of industry sectors that ACI serves.

Space – Will A Retrofitted Air Knife Fit My Production Line?

ACI air knives are designed to be more compact – enabling them to replace existing systems more easily. And to provide an efficient solution where competitors’ air knives may be too big and bulky to fit. Air knife systems tend to be larger than their compressed air counterparts. This is because air knives operate at much lower pressures (so they can save energy):

Compressed air systems deliver high-pressure air at low volumes through 8 mm pipes.
Air knives use less energy because they deliver low-pressure, blower-driven air in high volumes. This means using 50, 76 or 102 mm diameter tubing, which needs more space.

But the compact design of ACI air knives means you can now replace old and expensive compressed air systems where previously this may not have been possible.

Power – Do I Have Enough Capacity For A Retrofitted Air Knife?

This is a vital consideration. Virtually all ACI air knife systems run on three-phase power.

But significantly, it’s not uncommon for operators to call in ACI because they’re running out of power. They need to replace wasteful compressed air or DIY systems with energy-saving air knives to free up power for use elsewhere in the factory.

For optimum performance and maximum energy savings, it is important that each air knife plenum, nozzle or reciprocator delivers true laminar airflow – an even stream of air. This airflow must be balanced, with no underperforming low spots, no wasteful high spots and no air turbulence.

This is why some factories’ DIY air systems perform so badly and waste money: they have not been configured correctly to meet the precise requirements of the application. Most of these DIY systems we’re called in to replace are little more than plastic or metal tubes with hastily drilled air holes. There has been little or no consideration of:

the precise pressure required to achieve the desired result
how the air will flow under pressure
how to maximise air entrainment, how to draw more ‘free’ air into the path of the powered airflow (improving performance in a more cost-effective way)
the Coanda effect – the tendency of air to follow the path of a convex surface
how turbulence created elsewhere in the factory can interfere with the airflow
environmental factors such as climate and altitude (which affect air pressure).

Chart showing cost savings of Blower System vs Compressed Air

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Noise – Can A Retrofitted Air Knife Reduce Decibel Levels?

Noise reduction is often part of the remit when ACI is called in to solve air delivery challenges. Moving air creates noise. And this noise increases on a logarithmic – rather than linear – progression. So it does not take much for noise levels to rise rapidly. This is why air knives tend to be installed within designated ear protection zones. Low-pressure air knives are much quieter than high-pressure compressed air systems. However, we recommend specifying acoustic enclosures:

Fully enclosed systems – ACI’s LNL (Low Noise Level) air knives – with 304 stainless steel acoustic enclosures and optional pre-fitted conveyor plates. Choose from Mini, Standard or XL. Noise levels are well below 85dB(A).
Partial enclosures – ACI’s EL (Eye Level) Drying System – the blower is housed in a 304 stainless steel acoustic enclosure. Noise levels are around 98dB(A).

It’s also worth noting that air knives are much safer than compressed air. They also produce clean airflows with none of the oily contaminants sometimes found in compressed air.

Requirements For Retrofitted Air Knives

ACI air knives are custom-configured to ensure they suit your precise requirements and perform as specified and tested. Furthermore, they are also based on standard components to speed up delivery and installation times – and to give you the best possible return on investment. These are some of the questions our technical team will ask you before designing and configuring your retrofit air knife system:

What do you need it for? What is the process you need to optimise?
What do you need to achieve? What is your goal – to improve quality, boost output, save energy, or all three?
Do you already have an existing system? If so, does it use blower-driven or compressed air technology?
Do you to need to comply with particular standards or legislation?
What is your budget? With 50+ years of experience, we can forecast very accurately how soon your new air knife system will pay for itself.
Why now? What are the factors precipitating your need for a new air knife system?

Discover How ACI Has Helped Businesses Like Yours

It pays to partner with a world-class air knife specialist like ACI. Browse our case studies to see how we helped these companies.

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Get expert technical advice

Never specify an air knife straight from a website or brochure. There is a wide range of variables that can affect performance – including geographical/environmental factors. So we recommend that you always get specialist technical advice before embarking on your air knife project.

Contact ACI for specialist technical advice