FAQ about spacers and Why ventilation between stacked layers is of importance

Why is airflow between stacked layers important?

Proper ventilation allows air to reach all product surfaces evenly. Without sufficient airflow-channels, parts of the batch will be more ventilated than others.

This may result in;

• dissimilar characteristics for the pallet stack or batch
• longer process times
• risk of quality degradation or even damaged products

Amongst others, research from The Danish Technological Institute confirms that airflow distribution is one of the most important factors affecting efficiency when blast freezing.

Key point: Airflow between product layers usually facilitates a faster and more even process.

What are ventilation spacers?

Ventilation- or pallet spacers are aucellery products specially designed to create air-flow channels between stacked product layers.
Spacers most often have same size as Euro and Industrial pallets and can be manufactured of wood, steel, plastics or cardboard.

Ventilation spacers are as such designed to facilitate air-flow and thereby ventilation between stacked product layers during freezing, thawing, tempering, storage or transport.

Spacers enables air-flow to come into contact with product surfaces also in the middle of the pallet stack instead of only the outside facing products on the pallet load.

As the use of spacers also creates a more free air flow throughout the entire compartment, further noticeable process-improvements are achieved.

Lear more about VentiTeq’s spacers here

What could be the consequence of insufficient airflow between product layers?

Simply put, air always chooses the way with least resistance.
When airflow is restricted, it bypasses the products and travels around the products or pallet stacks instead of through these. This results in poor and unventilated spots in the chamber or compartment.

The consequences may include damaged products and/or quality differences, longer process times  increased energy consumption.

To compensate, operators often increase fan speed, which of course has some effect but also significantly increases energy consumption.

Problem: Air bypasses the product.
Solution: Use ventilation spacers to create airflow channels.
Effect: More uniform and shorter processes and ultimatively reduced energy consumption.

Why is airflow distribution more important than airflow volume?

Simply increasing airflow volume does not guarantee better ventilation.

The key is to ensure, that the air reaches and ventilates all products in the batch.

Well-directed airflow through the product stack is often far more effective than using larger fans or higher air velocity.

What is meant by “air bypass?

“Air-bypass” occurs when air flows above, below, or around the pallet instead of through the spaces between products. This reduces heat transfer efficiency and wastes fan energy.

Minimizing bypass airflow is a key objective in efficient design of freezing-, thawing and other compartmentr with palletstacks the require ventilation

What characteristics define an effective airflow channel?

An effective airflow channel should:

• Maintain a consistent gap between product layers
• Minimize airflow resistance
• Ensure uniform air distribution across the pallet
• Direct air through the product stack
• Prevent blockage or collapse during handling
• Ensure good support of the stacked layers and thereby stable pallet stacks. 
  
  

How can operators identify poor airflow distribution?

Common indicators for poor air-flow include:

• Uneven product temperatures
• Long freezing or thawing cycles
• High fan energy consumption
• Products freezing or thawing faster in some areas than others
• Large temperature differences between pallets.
• Spoiled products, (completely or partially) in parts of the batch

These symptoms often indicate that airflow is not reaching all products effectively.

What role does product stacking play in performance?

Even the best equipment cannot perform efficiently if products are stacked or placed incorrectly.

Consistent spacing, stable pallet construction, and controled paths for airflow are essential for achieving uniform processes and minimizing energy consumption.

Why are traditional wooden spacers not always the best solution?

In many ways, wood is a brilliant and versatile material.

When it comes to spacers, however, wood has the disadvantage of being an insulating material. This is further reinforced by that wooden spacers must be relatively strong in order to withstand the loads that spacers often are exposed to.

Wooden spacers therefore can insulate and partially block airflow and thereby create unnecessary air-flow resistance.

Well designed spacers in materials such as High Density Polyethylene (HDPE) allows manufacturing in thinner and yet more rigid designs with open profiles or airflow channels. 

Key point: HDPE spacers as VentiTeq’s can be constructed both thinner and more open than wooden spacers, thereby facilitating better airflow in the compartment

Which are the main difference between various spacer-designs? 

Spacers differ mainly in height, design and material.

• Height
  typically varies between 30 and 65mm. Generally speaking, the higher the spacer, the better air-flow, although this is also very much influence by the design and openness of the spacer.
• Design
  In addition to the basic premise of allowing air flow, design is always a compromise between the spacers having the desired stiffness, load-bearing capacity, stackability, lightness, and not least production suitability.
• Material

1. Facilitating Air-flow
   As the main purpose of inserting spacers between the box-layers is to facilitate air-flow between these, the height and openness of the spacers are definable for an effective spacer.
   Although higher spacer as such are more effective, it is of course crucial that the blast-freezer has space for the extra height that the spacers add to the pallet stack.
2. Box-layer support 
   As the cardboard boxes used in the food industry are getting ever thinner, these often have a tendency to collapse, when stacked. When one carton collapses, this unevenness easily spreads to the box-layer and then to the entire pallet stack, which thus becomes unstable.

   The VentiTeq NVS-III spacer offers a unique, edge-to-edge support of the box-layers, and can be applied even during road-transport

3. Quality and durability
   As freezer spacers are used in rather harsh environments, spacer quality and life-time togehther with the achieved savings are crucial for the return on the investment in these

Key points: There are significant differences between spacers. Consider which factors are most important in your particular set-up.
With a height of 50mm, a sturdi yet open design, VentiTeq spacers offers exceptional efficiency. Together with the unique support of the box-layers and its long life-time, VentiTeq spacers contribute as such to a high return on the investment

How do ventilation spacers improve industrial blast freezing?

As the the air- or ventilation spacers create consistent gaps between the stacked product layers, this allows the air to circulate freely through the stack. First of all this improves a more equalized heat transfer between all the stacked boxes and the ventilated air whereby all products in the batch better reach the target temperature at the same rate.

Equally important is, that the cold air flows more freely in the entire freezing compartment, whereby fan speed often can be reduced. This again leads to noticable energy savings.

Problem: Stacked products in a freezing batch reach target temperature at very different  times
Solution: Use ventilation spacers to create airflow channels.
Effect: More uniform freezing, shorter freezing time and reduced energy costs.

Can ventilation spacers reduce energy consumption?

Yes. Better airflow distribution and less air-flow resistance between stacked product layers requires lower fan speeds. According to The Danish Technological Institute  significant energy reductions can  be achieved by optimizing airflow and reducing unnecessary air movement.

Ventilation spacers may reduce energy consumption by helping the freezer work more efficiently. If airflow reaches the product better, the required freezing or thawing time will be shortended. With less restricted, better airflow in the entire compartment, also fan speed may be reduced, leading to noticable energy savings. The exact energy savings depend on the individual equipment, fan control, loading pattern and process targets etz.

Problem: Slow,  uneven freezing of the batch load in blast freezer
Solution: Use pallet placements and spacers to create conditions for the cold air to reach all pallets and box surfaces
Effect: Faster and more uniform freezing in Industrial blast freezers

Can spacers be used also during transport?

As processing and storage is increasingly outsourced to external, specialized service providersit often makes sense to apply the spacers at the manufacturing site, so that the pallet stacks do not have to be repacked with spacers at the service facility.

Traditionally spacers have not been suitable during transport. Mainly because stacked boxes had a tendency to collapse, if spacers did not fully support the box layers. This lead to damaged boxes and unstable pallet stacks.

Ventiteq NVS-III spacers have an unique edge-to-edget support of the box-layers making these suitable to be applied also during transport, as they facilitate the integrity of pallet stacks even under rough handling.

Problem: Collapsing boxes and unstable pallet stacks during handling and transport
Solution: Use rigid spacers with full support of the box layers
Effect: Process savings, as the spacers can be applied at the production site, avoiding time consumable repacking before entering the blast freezer

When should you consider ventilation spacers?

Ventilation spacers should be considered as a possible solution when when inconsistencies occur in the product batch, affecting product quality or processing times

Typical situations include:

• Pallet stacks freeze or thaw unevenly
• Centre layers are not or poorly ventilated
• Operational cycles are longer than expected
• Energy consumption is high
• Process capacity is a bottleneck
• Product quality varies between pallet layers

What is the main benefit of using VentiTeq spacers?

VentiTeq spacers are engineered with optimal airflow geometry, high durability, and easy handling in mind.
Our design focuses on performance, hygiene, and sustainability, helping our clients to achieve better freezing results with lower operational costs.

The main benefit is improved airflow through stacked food products during blast freezing or thawing. Better airflow can reduce freezing time, lower energy consumption, improve temperature uniformity and support better product quality.

In short: VentiTeq spacers help air or gasses reach stacked products more effectively.

Problem: Airflow is blocked inside pallet stacks.
Solution: Insert open-profile freezer spacers between product layers.
Effect: Faster, more uniform and more energy-efficient blast freezing.

What are the main factors I should consider when choosing a spacer solution?

There can be multible objectives when considering choice of spacers – top decision parameters include:

• Issues with product quality due to uneven process?
• Reduction of process time?
• Energy savings?
• Will spacers be applied also during transport – now or in the future?
• Box quality – issues with collapsing boxes?
• Ease of handling and durability?
• Compliance with sustainability goals
• Life time and ROI?
  
  

Automated or manual insertion and removal of spacers

VentiTeq spacers are designed to work seamlessly with both manual and automated handling systems, improving operational efficiency without needing major infrastructure changes.

Clients handling a limited quantity of pallets, most often insert and retrieve the spacers manually.

Semi automation of this process can be acchieved with automated pallet inverters. Learn more about such here

In fully automated processes, spacers are applied and retrieved fully automatically with robots.

Lifetime and ROI

VentiTeq spacers are made of long-lasting, recyclable HDPE designed for years of repeated use even in rather harsh conditions

Obviously ROI is influenced by individual setups, but based on feedback from our clients, ROI of less than 6 month are not unusual.

Getting started with spacers

VentiTeq is happy to offer product samples so you can experience the design and quality of the spacers and not least how these support your cardboard-boxes. However – in order to experience the full effect the spacers must be applied all pallet-stacks in your process batch – only in this way you can exploit the full potential of spacers by improving the airflow throughout your entire process compartment.

You are always most welcome to contact us or to complete our short Client Discovery Questionnaire
With years of experience from a wide range of clients around the world, we will do our utmost to asses you current setup, and objectively identify solutions that maximizes your freezing performance.

All inquiries are of course completely non-binding