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Ordinary nanofibre proven inferior to Ultra-Web®

Supplier: Donaldson Filters By: Written by Petra Meinke, senior product manager, Mark Belcher, media engineering manager and Debbie Olson, aftermarket product manager.
20 March, 2014

Recent technical analysis has uncovered significant performance differences between ordinary nanofibre cartridge filters and cartridge filters with proven Ultra-Web technology.

Tests show that ordinary nanofibre filters are measurably less effective than Ultra-Web filters: the tests conducted on the most recent introduction to the nanofibre filter field reveal high susceptibility to moderate heat and normal humidity.

In these typical ambient conditions, tests showed that ordinary nanofibres degrade - essentially melt away - and dramatically decrease the performance and life of the cartridge filter. The bottom line: the only assurance of cleaner plant air is proven Ultra-Web technology, truly advanced and perfected over 30 years in the field to perform in all ambient conditions.

When Donaldson first introduced Ultra-Web nanofibre cartridge filters for dust collection in manufacturing plants in 1982, it was a breakthrough technology compared to the industrial air filters then available (commodity cellulose media for cartridge collectors and woven fabrics for baghouses.) Engineered with a fine, continuous nanofibre layer that captured submicron dust particles on the surface of the media, Ultra-Web introduced the concept of a filter that allowed dust to be more easily released through pulse cleaning and promoted self-cleaning in the collector. Ultra-Web cleaned better and therefore lasted longer than commodity filters. This was truly a paradigm shift in industrial dust collection. 

Early refinements

However, today’s proven Ultra-Web technology is not the same Ultra-Web introduced in the early 80’s– and for good reason. There are typically refinements made to any new technology and Ultra-Web was no exception. The first generation of Ultra-Web filters developed by Donaldson 30 years ago encountered similar issues now facing new, ordinary nanofibre filters.

The nanofibre layer of ordinary nanofibre filters degrades in moderate heat and humidity because the fibres are fragile. While in principle smaller is better, these ordinary nanofibres have been taken too far and are less than 25 per cent of the cross-sectional area of Ultra-Web fibres today, making the nanofibres too delicate to withstand the rigors of a wide range of operating conditions.

While marketed as a comparable product, ordinary nanofibre filters have actually only caught up to where Ultra-Web was 30 years ago with the first generation of nanofibre technology.

In the early 1990's, another filter media comprised of a blend of 80 per cent synthetic and 20 per cent cellulose fibres came to market in an effort to simulate Ultra-Web technology. While Ultra-Web is a layered media comprised of a cellulose substrate and synthetics nanofibres, the 80/20 blends are made of cellulose and synthetic fibres blended together.

It is a depth-loading media, whereas the layers of Ultra-Web enable the surface-loading capacities.

Ordinary nanofibre tested in heat and humidity

In numerous accelerate lab tests in a temperature/ humidity chamber, ordinary nanofibre filters degraded rapidly by as much as 83 per cent in a matter of hours when subjected to temperatures ranging from 32°C to 71°C and various levels of relative humidity. It’s reasonable to assume that in industrial environments at high temperatures and humidity, degradation will occur.

Beyond season or region

While a 32°C temperature might initially trigger thoughts of potential problems in warmer climates or the height of Summer, many manufacturing environments, including those that are temperature controlled, can experience 32°C+ ambient conditions in any season because processing equipment can generate heat and moisture. Heat is one factor that can degrade the ordinary nanofibre layer – but humidity is actually the bigger culprit, since 40 per cent relative humidity is normal for most environments in any region, at any time of the year.

Ordinary nanofibre - DO.A.

Since ordinary nanofibre filters are susceptible to warm conditions and humidity, whether in the plant or during transit, there's also the likelihood that the nanofibre layer will degrade even before the filters reach their final installation destination. Moderate heat and humidity experienced during shipment could potentially remove the nanofibres from ordinary nanofibre filters.

That means users are likely to receive the equivalent of commodity type filters with little to no remaining nanofibre. And depending on the storage heat and humidity conditions at the plant, the nanofibres could disintegrate while sitting on the shelf before the filters are installed in the cartridge dust collector.

Degraded nanofibre = degraded performance 

Once the ordinary nanofibre layer has deteriorated the media effectively reverts to being a commodity cellulose depth-loading media.

Two consequences could result:

  1. The protection against sub-micron particulate would be gone. The cellulose media will, of course, continue to filter out the larger particulate by capturing it in the depth of the media mat, but the nanofibre layer that collects the very fine particles would be absent.
  2. Without the surface loading qualities of the nanofibre layers, the pulse mechanism in the dust collector will have to pulse more often to clean the filters. More pulsing means more compressed air usage and more energy consumption.

Ultra-Web - proven and protected

Precisely how is Ultra-Web superior to ordinary nanofibre filters? Ultra-Web began more than 30 years ago just like ordinary nanofibre has today - with 50 per cent finer fibres that were more fragile and delicate than today’s more robust Ultra-Web fibres. During the last 30 years, Donaldson has advanced and perfected Ultra-Web technology to optimise fibre structure and fibre diameter so that it is stronger and lasts longer in all environmental conditions. Ultra-Web performs in conditions ranging from -29°C to 82°C.

By extensively testing and enlisting our more than 90 years of filtration expertise, Donaldson developed better subsequent generations of Ultra-Web filters with the right size fibres that provide the best combination of longer filter life, cleaner air and lower pressure drop. This superior generation of Ultra-Web technology is backed by 80 issued and pending patents worldwide and proven in the field for more than two decades.

Today's Ultra-Web technology is made with an electrospinning process that applies a continuous strand of microscopic polymer of 0.2-0.3um in diameter. This forms a web-like net, with very fine interfibre spaces, that keeps dust on the filter surface so it can be easily pulsed off during cleaning.

By comparison, today's commodity cellulose and blended media have fibres at least 10 microns in diameter and large pores between fibres (up to 60 microns) that allow dust to penetrate deep into the media, quickly plugging and reducing filter life.

Are you paying nanofibre prices for commodity filter performance?

Ordinary nanofibre filters claim a higher MERV 15 rating (Minimum Efficiency Reporting Value) than standard Ultra-Web MERV 13 filters, although variations of Ultra-Web filters come with MERV 13, 14 and 15 efficiency ratings depending on the application needs. In theory a higher MERV rating indicates higher efficiency in capturing submicron dust particles in the 0.3 to 0.1 micron range; however, there is a substantial difference in efficiency in the ordinary nanofibre layer degrades during shipping, storage or use in heat and humidity.

In warm, humid, ambient conditions, ordinary nanofibres melt away leaving the commodity type depth-loading cellulose media underneath, unable to effectively capture submicron particles. Cellulose media typically ranges in efficiency from MERV 8 to MERV 10, which is not rated to filter submicron dust particles. In short, you’ll experience higher pressure drop, shorter filter life, greater compressed air use to clean the filters, and higher energy consumption - all at a higher nanofibre filter price.

Think extraordinary, not ordinary

Ultra-Web is often imitated but never replicated. Backed by 80 issued and pending patents, Ultra-Web technology is only available from Donaldson. Don’t be confused by ordinary nanofibre filters that claim to offer the same performance advantages as Ultra-Web.

Only Ultra-Web is proven and perfected to provide high filtration efficiency, longer life and greater energy savings.