Optimizing Filtration Surface Area – how much is too much?



We have been monitoring the recent ‘competition’ in the filtration industry regarding who can put the most surface area into a single Gas Turbine (GT) inlet air filter with great concern.​


Because most customers may not understand the potential negative consequences of adding filtration surface area beyond a certain limit.

When is too much, too much?

In general, we can say that the benefits of adding filtration surface area to a filter element are typically considered to be:

Longer lifetime; and
Reduced dp (pressure drop)

While in general it is true that increasing filtration media surface will enable the filter lifetime to be longer but when adding filtration surface beyond a certain point, it will start affecting the free air flow and will actually start to increase the dp, thus reducing the operational lifetime of a filter.

If we look at filter optimization only from the dp optimization point, we can note that adding the surface area is decreasing the dp value of the filter, as long as the open area between pleats is not restricting the flow. The initial reduction of dp is caused by the reduction of air velocity through the filtration media. At some point the filtration media surface reaches the point where the narrow open area of pleats is restricting the flow more than the added area will reduce the dp , then further adding the surface will only cause an increase in the dp.

Sweet spot for filtration - lowest dp with highest filtration area maximizing the filter lifetime

When trying to find a GT inlet air filter´s optimum dp with maximizing the lifetime, it is the ‘sweet spot’ you want to go for – lowest dp with the highest filtration area.

It has to be noted that each filtration media has different properties which are affected also by the air flow so it is impossible to say the general value for a sweet spot as it will vary between filtration classes and different brands making the comparison very difficult.

For us the sweet spot for optimum large surface MAGNUM E12 is currently at 54m2 (580ft2) per filter, which is providing the solution for locations with high levels of small dust concentration or for inlet air houses with only prefilter + EPA filter possibilities – and still remaining on a reasonable dp level.

MAGNUM E12 with 54m2

It is hard to aim for the optimum solution as all materials have different properties, but you can always contact your ‘Friendly Filter Guy’ to hear about Eagle Filters’ optimum filtration solution!


William Ruthin katu 1 / 48600 Kotka / Finland