Pleated filters: the great problem solver

Undersized dust collectors, differential pressure limiting production and overworked workers encumbered by long maintenance: the dust bag filter has no shortage of problems. Before scrapping a dust collection system and rebuilding expensive infrastructure, it’s worth considering a simple filter replacement with a pleated style filter to solve some of these headaches.

While pleated filters have a higher initial cost than bags and cages, the savings in operating costs can be significant over time in many applications. By packing three to four times as much filter area in a shorter package, pleated filters can often cost-effectively reduce dust emissions, pressure drops, and filter durability issues.

Some filter elements and pleated cartridges have already solved these problems, saving downtime in the food, pharmaceutical, wood, aluminum, energy, cement and other industries, with gas temperatures ranging from -20 to 400 ° F. Application engineers can help evaluate individual applications and determine if dust type and performance parameters are worth considering pleated filter options.

Compact size and increased filtration area, lower pressure drop

Since the folded media of a pleated filter contains a larger surface area than a bag of the same diameter and length, it reduces the filtration speed and, therefore, often reduces the pressure drop across the filter media. filtration. While this can lead to lower energy bills, the real savings often come from increased production.

The strategic placement of the pleated filters reduces the speed of the box. When the speed of the box is too high, it prevents dust from falling from the filter during cleaning. The released dust remains in suspension and re-adheres to the surface of the filter. Pleated elements can solve this problem by reducing the total number of filters without sacrificing the total filtration area. This creates more free space between the filters and therefore reduces the speed of the gearbox.

Depending on the diameter of the filter, a traditional filter bag can be replaced with a pleated filter one-third the length and with the same filter surface.

Better durability reduces downtime

The difference in filter length between bags and pleated filters is also factored into filter wear and frequency of replacement. If the filter bags wear out at the bottom, replacing them with shorter pleated elements pushes the filters out of the abrasion area (see Figure 1). An added benefit: Unlike filter bags, pleated filters have a protective urethane or metal tip at their base which provides additional protection against abrasion. This function increases the life of the filter.

Image courtesy of Parker Hannifin

Figure 1: The pleats provide more surface area while pushing the filters out of the abrasion area.

When the pleated filters eventually need to be changed, the process is faster and less labor-intensive than bag and cage types, reducing downtime and labor costs. A pleated filter element is a one-piece unit and does not require the often cumbersome removal of a cage stuck in a long filter bag. Since the environment is often hot and dusty when removing bags, maintenance personnel generally prefer to change pleated elements rather than filter bags and cages.

Image courtesy of Parker HannifinFilters_Pliss_PARKER_HANNIFIN.png

Pleated filters have a protective urethane or metal tip at their base that provides additional protection against abrasion.

Rugged, forgiving design maintains filtration efficiency

The more often a filter is cleaned, the faster it wears out. As filter bags wear out, particulate emissions increase. Today’s stringent emissions standards often determine the life of the filter.
Typically, most emissions are released during pulse cleaning. A pleated filter with a larger surface area and permeable dust cake will pulse less frequently than a filter bag. This lengthens its life cycle based on emissions. When pulsing, an iPlas strap (see Figure 2) holds the pleats firmly in place and maintains pleat spacing.

Image courtesy of Parker HannifinFigure_2_PARKER_HANNIFIN.jpg

iPLAS uses a thermoplastic polymer creating a rigid integrated band providing excellent strength and durability while maintaining flexibility

Another point for folds: a more tolerant installation approach. A number of pleated filters include a soft rubber or molded urethane top that creates an effective seal at the tubesheet and accommodates certain variations in the holes in the tubesheet. Metal-topped options use a simple felted cuff in the installation process. The bags, on the other hand, must be perfectly adjusted to create a seal.

Pleated filters can be a cost effective alternative to replacing aging dust collectors often deemed necessary to meet more stringent emissions standards. A filter exchange can alter performance, seal better, and reduce the number of pulse cycles required. Dust conditions and media surface can influence performance and efficiency when passing bags and cages to pleated filter elements. Parker engineers are available to discuss specific applications and in some cases run simulations to determine how pleated filters can solve specific performance issues.

Dale Kadavy is Senior Product Engineer and Matthew Campbell is Technical Sales Director, Parker Hannifin. For more information, visit parker.com/bha.

When to consider a pleated filter

Generally, pleated filters offer advantages for applications with a current filter bag which is:
* Over 4 ” in diameter
* Less than 20 ft
* Handling of free flowing dust

Other situations, especially those with sticky dust, require individual assessment.

Folded filters: fact or fiction?

Pleated filters are often overlooked due to their modest appearance or initial cost. In truth, pleated filters are effective and versatile problem solvers.

Myth: Pleated filter elements don’t work in heavy industrial applications.
False. When properly selected and configured for the application, pleated elements perform well in most industries and have eliminated many filtration bottlenecks.

Myth: Creating space under the filter bags will cause performance issues.
Allowing more open space and a low air velocity area with pleated filters will result in a larger drop chamber and reduce potential abrasion issues.

Myth: Pleated filters are more expensive.
Yes, a pleated filter with comparable performance costs more upfront. The savings come from lower operating costs due to lower pressure drop, lower emissions, and faster, less labor-intensive replacements. In some applications, the life of the filter is considerably longer.

Myth: Pleated elements are for highly specialized applications.
False: Pleated elements are suitable for a wide range of dust collection applications including food, pharmaceutical, wood, aluminum, cement and steel processes.

Myth: It’s not long enough. It won’t work.
Appearances can be deceptive. The folded media design of the pleated filter packs a lot of area into a small space. It can match the performance of the bag with as little as a third of the length.

Myth: Pleated filters are not suitable for a bottom access design.
Not true. The one-piece pleated elements can be installed easily via bottom access in place of a bag and cage filter.

Image courtesy of Parker HannifinSection_Filtres_Plis_PARKER_HANNIFIN.jpg

Pleated filters

Fixed issue: maintenance and efficiency issues with the high efficiency separator

In addition to the high differential pressure and high compressed air consumption, the bag filters in the pulse jet bag filter of a high efficiency separator had to be replaced every two years or more often.

Replacing bags and cages with pleated elements increased the filtration area by 75%. This switch reduced the differential pressure by 55%. The pulse pressure increased from 100 to 60 psi, and the pulse cycles could be extended every 10 to 360 seconds. With less wear, the filter life has been extended to over five years.

Issue solved: Brewer’s high maintenance hot and humid bag filter

A brewer’s outdoor pulsed bag filter must withstand the elements and is particularly vulnerable to hot, humid and humid temperatures. As a result, crews had to check daily for malfunctions in baghouse operation and perform a complete bag change every six months, which involved skilled labor, significant downtime and material expense.

Replacing existing filter bags and cages with pleated filter elements increased airflow through the bag filter and reduced pressure drop, helping to extend filter life and minimize maintenance. Compressed air usage dropped from 95 to 60 psi, and specialist crews were no longer needed for simplified filter changes, which took 75% less time. Daily functional checks were no longer necessary and the installation immediately followed four months with no functional problems.

Note that compressed air consumption will vary across applications depending on pulse cleaning regimes and filter media specifications. Parker technical account managers and application engineers can assess the efficiency of compressed air for specific applications.