Mann + Hummel launches high end air filter - industry news

Diesel Progress North American Edition, March, 2004

As a high end, higher performance complement to its well established Europiclon air filter for mobile and stationary engine-powered equipment, the Industrial Filters division of Mann + Hummel has launched its Picoflex compact air filter system.

"Where the Europiclon combines high performance air filtration with extremely comfortable, flexible installation, the Picoflex is designed to offer very high performance in a very compact package," noted Jens Hahn, product manager air filters. "It is our response to changes in mobile equipment design which have seen the use of. more and more turbocharged engines with their higher intake air demand and an ever greater number of devices all competing for space under the engine hood, like air conditioning pumps and condensers and charge-air coolers."

In fact, Hahn stated, the Picoflex achieves a 40% increase in filtration performance, or what might be termed "filtration density"--the ratio of particle retention to installation volume, making it ideal for mobile equipment working in high dust environments. "This gives OEMs of mobile equipment a very useful choice," he said. "Either the smile filtration performance can be packed into a 40% smaller space or 40% more filtration performance can be packed into the same space."

At the start of the development of the Picoflex, Hahn noted Mann + Hummel started with a clean sheet and used the QFD (quality function deployment) method to define needs of the markets. "There was strong input from OEMs via our marketing department and our field engineers, and of course from the technical functions, who used their long experience to select and execute the best solutions."

The result is an air filter featuring two particle separation stages with a simplified "in-at-one-end, out at the other" airflow path and featuring the most efficient cyclone stage yet offered by Mann + Hummel, Hahn stated. "The straight airflow patch allows us to insert the filter element radially into its housing--filter elements are traditionally an axial fit--to make it very easily accessible and removable. Depending on application, the main filter element can be backed-up by a secondary safety element, and the straight through air path greatly simplifies ducting. At one engine builder it has already been instrumental in the relocation of a turbocharger to a more compact location."

Mann + Hummel is especially proud of its high performance cyclone, for which patents are being sought. "It consists of 46 small, interlocking inlet and outlet ducts of rectangular section, with the inlet ducts integrated into the Picoflex's end cover," Hahn said. "Compared with the 85% particle pre-separation of the Europiclon's more traditional cyclone, the Picoflex's cyclone gives 95% preseparation. This 10% increase in preseparation actually results in a threefold increase in filtration effect since residual particles are 5% not 15% of the total intake."

The main filter element of the Picoflex filter is a new design called the CompacPlus element by Mann + Hummel. "The CompacPlus is a honeycomb depth filter in a new filter medium, and offers 50% higher filtration surface to the incoming air than radial pleated types," Hahn noted. "Because of the Picoflex's space-saving, flat sided oval housing of the Picoflex, we have used molded on axial foam seals on the CompacPlus element. It is inserted radially into the housing where the seals compress against the end of the bottom of the housing and the housing cover. It is clipped between the cover and compressed between a special flame and the clean air nipple.

"As such it can be readily removed for cleaning and is very tolerant of frequent removal for this purpose, although as a manufacturer we recommend, first and foremost, replacement of the element after life expiry, or cleaning as rarely as possible, i.e. only on the basis of the filter condition indicator."

The secondary element, where fitted, is a radial fit onto an oval extension on the clean air outlet flange. In contrast to the flat-sided housing profile, the flange extension features a rounded elliptical form to ensure radial pressure on the entire perimeter of its integral lip seal. It provides particle retention in the event of damage to the main element. "Especially as a result of overenthusiastic cleaning using compressed air," Hahn noted with a smile. "Due to its housing design, none of the Picoflex's air ducting needs to be removed to allow removal of the filter elements."

Overall, with its new cyclone and depth filtration using the special medium, the Picoflex achieves an overall separation efficiency of 99.98%.

Scavenging of the cyclone stage is by a suction pipe. Suction can be provided by an ejector in the engine exhaust, downstream of the silencer, by the engine cooling fan or by a dedicated fan. To avoid fouling the cooling Fan, we recommend either the exhaust ejector or the dedicated fan. "Obviously the exhaust ejector is an elegant low cost solution. It can be integral to the silencer or supplied by Mann + Hummel as a separate customized part," Hahn pointed out. "In any case, more and more radiator fans are thermostatic and operate only sporadically, which is not suitable for our cyclone's dust ejection needs."