How to Compare Filter Data Sheets Like an Engineer

If you are comparing air filters for a plant room, office building or industrial site, the datasheet should help you make a clear decision, not create more questions. The trick is knowing which fields tell you how the filter will perform in your system, and which ones only matter in context.

At Total Air Filtration, we work with mechanical contractors, facility managers and procurement teams every day, so we know the same datasheet can look very different depending on the application. Here is how to read the key details like an engineer.

Start with the efficiency class

The efficiency rating is usually the first place to look, but it should never be the only field you check. It tells you what size and type of particles the filter is designed to capture, but the meaning depends on the test standard used.

Common rating systems you will see

• •EN 779 classes such as G3, G4, F5 to F9 are still widely used in Australia, although the standard has been superseded by ISO 16890.
• •ISO 16890 ratings describe performance against particulate matter fractions and are now common on newer datasheets.
• •MERV ratings are used in some markets, but they do not convert directly to EN 779 or ISO 16890 classes.
• •HEPA filters are rated differently again. Under EN 1822, H13 is at least 99.95% efficient and H14 is at least 99.995% efficient at the most penetrating particle size, or MPPS.

A good datasheet will show the rating clearly and name the test standard behind it. If it does not, you may be comparing different systems as if they were the same thing.

Ask what the rating means in your system

A high efficiency class is not automatically the right choice for every installation. In a commercial HVAC system, the filter needs to suit the fan capacity, the ductwork, the air handling unit and the maintenance access available.

For that reason, always check whether the rating is being used for:

• •pre-filtration
• •general comfort conditioning
• •higher efficiency filtration in sensitive areas
• •terminal filtration in specialised applications

If you are unsure what standard or class your site should be using, confirm the requirement with the mechanical services engineer or building owner. For some projects, AS 1668.2:2024 may be relevant to the ventilation design, but the site requirements still need to be confirmed for the actual installation.

Read the pressure drop carefully

Pressure drop is one of the most practical numbers on the page. It shows how much resistance the filter adds to airflow. Engineers look at this because a filter that performs well on paper may still be a poor fit if it loads too quickly or creates too much resistance for the system.

What to look for on the datasheet

• •Initial resistance or initial pressure drop: the resistance of a new filter when first installed.
• •Final resistance or recommended terminal pressure drop: the point at which the filter should usually be considered for replacement.
• •Airflow range: the pressure drop should be read at the airflow your system actually uses, not just at a generic test point.

If the datasheet only gives one pressure drop figure without context, check whether it is based on a specific airflow or face velocity. The number can change significantly once the filter is put into a real system.

Why it matters for maintenance planning

Pressure drop is often the best way to decide when a filter needs attention. If gauges are fitted, monitor them as part of normal site checks. Inspection frequency depends on the system, site conditions and dust load, and you should follow the filter and equipment manufacturer instructions rather than rely on a fixed calendar.

For sites with variable dust loading, such as workshops, kitchens, loading docks or plant rooms, pressure drop trends are often more useful than visual inspection alone. If you need help planning a maintenance approach, our filter servicing and commercial filter servicing pages may help.

Check the media type and construction

The media type tells you what the filter is made from and how it is likely to behave in service. This is where datasheets can reveal a lot more than the rating line alone.

Typical media details to compare

• •Synthetic media: common in many pleated filters and often used where consistent performance and moisture resistance are important.
• •Fibreglass media: often seen in specific high efficiency or speciality applications.
• •Pleated media: increases surface area and can help manage pressure drop.
• •Bag or pocket construction: provides greater media area and is often used where longer service life is needed.
• •Rigid or panel construction: common where space is limited or a compact filter is needed.

Also look at how the filter is built:

• •frame material
• •seal type
• •separator design, if applicable
• •whether the filter is supported for the airflow direction in your system

These details matter because two filters with the same nominal rating can behave differently once installed. A strong frame and good sealing can help reduce bypass, while a poor fit can undermine the whole installation.

Washable or not?

Some filters are designed to be washable - check the product instructions. Do not assume a filter can be cleaned and reused just because it looks sturdy. If a datasheet is unclear on cleaning or reuse, ask before ordering.

If you need a non-standard size or a specific construction, our custom air filters service may be a better fit than forcing a close enough option into place.

Confirm the test standard behind the data

A datasheet is only useful if you know how the numbers were measured. The standard defines the testing method, so it gives context to the efficiency and pressure drop claims.

Standards you may encounter

• •ISO 16890 for general ventilation filters
• •EN 1822 for HEPA and ULPA filters
• •EN 779 on older datasheets, still commonly referenced in Australia for legacy systems

The key point is that rating systems do not convert neatly from one to another. If one supplier gives an EN 779 class and another gives ISO 16890 or MERV, you should not assume they are interchangeable without checking the test basis.

What to check beyond the standard name

• •whether the test was done at the airflow relevant to your application
• •whether the efficiency is listed as an average, minimum or initial value
• •whether the data applies to the whole filter or only the media sample
• •whether the product has been tested as supplied, not just as a material sample

If the datasheet is vague, ask for the full test reference or a product sheet with clearer details. Procurement teams often focus on the headline rating, but engineers will also want to know how the test was conducted.

Compare the practical details, not just the headline number

Once you understand the rating, pressure drop, media and standard, compare the rest of the sheet with the site in mind. This is often where the right choice becomes obvious.

Useful questions to ask

• •Will the filter fit the existing frame, rack or housing?
• •Is the available depth enough for the selected filter type?
• •Can the system handle the initial pressure drop?
• •Is the media appropriate for the dust load and operating environment?
• •Does the product suit the maintenance access on site?
• •Are there any special requirements from the equipment manufacturer?

For contractors and facility teams, it also helps to keep records of what is already installed. If you are unsure about dimensions or you need help matching an existing unit, our guide on how to measure an air filter is a useful place to start.

A simple way to compare two datasheets

When two filters look similar on paper, compare them in this order:

• •confirm the rating system and test standard
• •check the initial pressure drop at the actual airflow
• •review the media type and construction
• •verify dimensions, frame and sealing details
• •look for any installation or maintenance notes

This approach helps you avoid choosing on headline efficiency alone. In practice, the best filter is the one that fits the equipment, suits the site conditions and can be maintained properly over time.

Need a filter matched to your site?

Total Air Filtration is a family-owned air filter manufacturer and supplier in Hillcrest, Brisbane QLD, and we can help you compare datasheets, supply the right filter, or make a custom solution when standard sizes will not do. Call 07 3800 3448 or request a quote.

You can also browse our products or contact us if you want help choosing the right option for your application.