How to Compare Two Air Filters with the Same ISO 16890 Rating

When two air filters carry the same ISO 16890 rating, it is easy to assume they will perform the same in the real world. In practice, that rating only tells part of the story. To compare products properly, you need to look beyond the headline classification and check the data sheet details that affect airflow, resistance, service life and how the filter is built.

Why the ISO 16890 rating is only the starting point

ISO 16890 is a useful standard because it describes how a filter performs against airborne particle sizes that matter in ventilation systems. It helps buyers compare filters on a common basis, but it does not tell you everything about how two products will behave once installed.

Two filters may both be rated for the same ePM class, yet differ in:

• •how much filter media they contain
• •their initial pressure drop
• •how much dust they can hold before loading up
• •how evenly they are constructed and sealed

For facility managers, buyers and contractors, the practical question is not just “What is the rating?” but “How will this filter run in this system, on this site, with this dust load?”

If you are working to a ventilation specification or reviewing plant room options, it is also worth confirming the site requirements with the mechanical services engineer or building owner, especially where AS 1668.2:2024 is involved.

Compare the media area, not just the face size

A common mistake is to assume that two filters with the same nominal dimensions must contain the same amount of media. They do not.

The effective media area is one of the most important clues on a data sheet. More pleated media generally means more surface area for air to pass through, which can lower resistance and help the filter load more gradually. Less media area can mean the filter reaches a higher resistance sooner, even if the rating is the same.

When comparing products, check for:

• •pleat depth and pleat count
• •whether the media is tightly packed or more open
• •usable media area versus outer dimensions
• •whether the filter has spacers or separators that keep pleats open

A filter with more media area may not always be the right choice for every application, but it is a strong indicator that the product may have more room to hold dust before airflow becomes restricted. That is especially important in systems where access is awkward or maintenance is disruptive.

Look closely at initial pressure drop

Pressure drop shows how much resistance the filter adds to the air stream. On a data sheet, you will usually see initial pressure drop at a stated airflow. This figure is important because it affects how hard the system must work to move air through the filter.

Two filters with the same ISO 16890 rating can have very different initial pressure drop values. That difference often comes down to media choice, pleat design and how open the filter is across its full face.

When reviewing pressure drop, ask:

• •Is the value stated at the same airflow for both filters?
• •Is the test condition clearly shown on the data sheet?
• •Does the filter maintain even airflow across the whole surface, or does it appear prone to loading in one area first?

A lower initial pressure drop is not automatically better if the filter has less media area or poorer dust capacity. The better comparison is the balance between resistance, dust loading and construction quality.

If you are reviewing existing plant performance, filter servicing or commercial filter servicing can help you assess what is actually happening on site rather than relying on the nameplate alone.

Dust holding capacity matters in real service

Dust holding capacity is one of the clearest ways to tell whether two filters with the same rating will deliver the same service life. This figure tells you how much dust the filter can retain before reaching a stated terminal resistance in the test.

A filter that holds more dust can often stay in service longer before replacement is needed, depending on the site conditions and operating hours. But the number only makes sense when you compare like with like:

• •the same test method
• •the same airflow
• •the same terminal pressure drop basis
• •the same particle loading conditions

If the data sheet does not explain the test basis clearly, be cautious about direct comparisons. Some products may present impressive figures that are not easy to compare fairly with another manufacturer’s data.

For buyers, this means the best value is not always the cheapest unit price. A product with better dust holding capacity may suit a dirty plant room, a workshop environment or a site with variable dust loads more effectively than a lighter-duty option.

Build quality affects performance more than many buyers expect

Even when ratings and test figures look similar, build quality can make a major difference to how a filter performs in service. Poor construction can allow bypass, collapse under load or uneven dust distribution across the media.

On the data sheet and in the product images, look for signs of sound construction such as:

• •a rigid frame that holds its shape
• •even pleating and consistent spacing
• •secure bonding between media and frame
• •good sealing at the frame edges
• •sturdy separators, if used

A filter that looks neat on paper but is weak at the frame or seal may not perform consistently in the field. Likewise, if the media is poorly supported, it may sag or distort as resistance builds, which can shorten usable life.

This is why contractors often prefer to compare not only the rating, but also the overall design and supplier support. If the application needs a non-standard size or a specific configuration, custom air filters may be a better fit than forcing a near-match into a demanding frame.

What to check on the data sheet before you buy

When you are comparing two filters with the same ISO 16890 rating, use the data sheet to build a clearer picture of real performance.

Useful items to compare include:

• •ISO 16890 classification and test basis
• •media area or pleat details
• •initial pressure drop at the stated airflow
• •dust holding capacity and terminal resistance basis
• •construction details such as frame material and seal type
• •dimensions and depth, including any tolerances
• •recommended installation orientation, if stated

It also helps to confirm whether the filter is intended for general HVAC use, pre-filtration, finer particulate capture, or a particular system layout. Some filters are designed to be washable - check the product instructions rather than assuming the same cleaning method applies to every product.

If you need help measuring the existing filter correctly before ordering, how to measure an air filter is a practical place to start.

Make the comparison match the application

The best filter is not always the one with the highest number on the page. It is the one that suits the system, the maintenance access and the dust conditions on site.

A sensible comparison should ask:

• •Will this filter maintain acceptable airflow in the existing system?
• •Is there enough media area for the expected dust load?
• •Does the construction look robust enough for the installation environment?
• •Is the data sheet transparent and comparable?
• •Does the filter size and frame style match the equipment properly?

For some projects, a standard product from our products may be suitable. For others, a tailored option from custom air filters may be the better choice, particularly where dimensions or performance needs are unusual.

Inspection frequency depends on the system, site conditions and dust load. Follow the filter and equipment manufacturer instructions, and monitor pressure drop where gauges are fitted so you can judge when service is actually needed.

Talk to Total Air Filtration

Total Air Filtration is a family-owned air filter manufacturer and supplier in Hillcrest, Brisbane QLD, established 2009. We can help you compare product data, supply the right filter for the job, or make a custom solution when standard sizes are not the best fit.

Call 07 3800 3448 or request a quote. You can also contact us or view the industries we supply if you want to see where our filters are commonly used.