Liquid filters get a reboot

Engineering tackles flow capacity, operating life and researchers have worked to address liquid filtration challenges such as throughput volume, integrity, and the availability of replacement filters.


Tapered pores improve throughput while providing an optimal cutoff range for sterilization. Image courtesy: Donaldson Inc.The global beverage industry is undergoing a growth boom. A recent forecast predicts that combined sales of alcoholic and non-alcoholic beverages will grow 3% a year, reaching $1.9 trillion by 2021. Key drivers are growing urbanization, changing lifestyles, and disposable income. The bonanza puts heavy production demands on the processors of bottled water, carbonated drinks, juices, coffee and tea, beer, wine, and spirits. 

As beverage processors function at top speed, they’re requiring more from system components in terms of speed, performance, and cost of operation. One area ripe for improvement has been liquid filtration. Traditional technology—generally melt-blown polypropylene media inside a linear cage—has changed very little over the past three decades. Filtration is critical to removing dirt, debris, and bacteria from ingredient water, concentrates, flavorings, and other liquids; yet the harsh conditions of processing and sterilizing have historically worn out filters quickly and raised concerns about integrity. To solve this challenge, a team of 40 materials scientists and engineers collaborated with major beer and soft drink brands on two years of development and testing. The user-manufacturer group tackled three historic liquid filtration challenges: 

  • Throughput volume
  • Integrity and lifecycle
  • Availability of replacement filters.

In 2016, full-scale manufacturing got underway in a clean-room facility in Haan, Germany. The result of the venture is a complete reset of the media, cage structure, and production process in liquid filtration. These elements now are available commercially. Here is how the engineering team addressed longstanding liquid filtration challenges with new technology.

Throughput volume 

A filter unable to keep up with high-volume flow causes pressure loss, which slows production and wastes energy. How well a filter handles a high flow rate is driven primarily by the volume of media in the cartridge, along with the media’s pore size and length. Because the industry standard for liquid filter vessels is to use cartridges of 2.75 in. diameter with length increments of 10 in., there has been a limited ability to increase media volume within this defined physical space. 

A clean manufacturing facility in Haan, Germany produces a new generation of filters using a single-flow process. Image courtesy: Donaldson Inc.To solve this space problem, materials scientists on the project chose a unique polyethersulfone (PES) media with asymmetric, tapered pores. The pores graduate in diameter to a microscopic size at the clean side of the process, providing the optimal cutoff range necessary for liquid sterilization while minimizing restriction to flow. 

In addition, the development team was able to pack 20% more of this new material into a standard 2.75 in. diameter cartridge, in part through redesigning the cage structure. Using a rhombus pattern, every pleat in the filter has equal exposure along the filter length, opening up 10% more free space than previous configurations. This extra space optimizes flow, reduces pressure drop, and creates more consistent loading characteristics.

Together these changes make the new elements capable of processing more fluid without increasing assembly size or pumping pressure, which translates to energy savings and increased production. 

Integrity and lifecycle 

Filter media is a delicate, precision material, so the cage around it needs to resist collapse. Structural failure is a risk in food and beverage plants that process highly viscous fluids, use high operating temperatures, or practice steam sterilization, all which tend to soften filter cages over time and through repeated use. (Steam exposure often occurs in non-ideal process design, as well.) Any cage twisting during filter replacement also can change the shape of the PES membrane and reduce its effectiveness 

For these reasons, cage strength was a key goal in the engineering project. The same structure that created greater flow space—triangulations similar to bridge supports—was confirmed to deliver greater stability as well. This support cage resists deformation and stands up better to pressure differential during high volumes of fluid processing. The result is improved food safety, lifecycle, and overall cost savings.

Filter replacement 

The third challenge for liquid processors has been enduring long wait times for compatible filter parts. Processing applications vary so widely that thousands of unique components exist in various lengths, media, micron ratings, elastomer types, and end connections. Waiting for a supplier to manufacturer and ship a one-off part can cost weeks of downtime.

To address this problem, engineers working on the new filter technology developed single-flow manufacturing. Components in each 10 in. element module, including a specific length or end-cap style, can be quickly custom-manufactured one at a time with a choice of media. 

Colter Marcks is in the engineering manager for Donaldson Company’s Process Filtration Division. 


Top Plant
The Top Plant program honors outstanding manufacturing facilities in North America.
Product of the Year
The Product of the Year program recognizes products newly released in the manufacturing industries.
System Integrator of the Year
Each year, a panel of Control Engineering and Plant Engineering editors and industry expert judges select the System Integrator of the Year Award winners in three categories.
October 2018
Tools vs. sensors, functional safety, compressor rental, an operational network of maintenance and safety
September 2018
2018 Engineering Leaders under 40, Women in Engineering, Six ways to reduce waste in manufacturing, and Four robot implementation challenges.
GAMS preview, 2018 Mid-Year Report, EAM and Safety
October 2018
2018 Product of the Year; Subsurface data methodologies; Digital twins; Well lifecycle data
August 2018
SCADA standardization, capital expenditures, data-driven drilling and execution
June 2018
Machine learning, produced water benefits, programming cavity pumps
Spring 2018
Burners for heat-treating furnaces, CHP, dryers, gas humidification, and more
October 2018
Complex upgrades for system integrators; Process control safety and compliance
September 2018
Effective process analytics; Four reasons why LTE networks are not IIoT ready

Annual Salary Survey

After two years of economic concerns, manufacturing leaders once again have homed in on the single biggest issue facing their operations:

It's the workers—or more specifically, the lack of workers.

The 2017 Plant Engineering Salary Survey looks at not just what plant managers make, but what they think. As they look across their plants today, plant managers say they don’t have the operational depth to take on the new technologies and new challenges of global manufacturing.

Read more: 2017 Salary Survey

The Maintenance and Reliability Coach's blog
Maintenance and reliability tips and best practices from the maintenance and reliability coaches at Allied Reliability Group.
One Voice for Manufacturing
The One Voice for Manufacturing blog reports on federal public policy issues impacting the manufacturing sector. One Voice is a joint effort by the National Tooling and Machining...
The Maintenance and Reliability Professionals Blog
The Society for Maintenance and Reliability Professionals an organization devoted...
Machine Safety
Join this ongoing discussion of machine guarding topics, including solutions assessments, regulatory compliance, gap analysis...
Research Analyst Blog
IMS Research, recently acquired by IHS Inc., is a leading independent supplier of market research and consultancy to the global electronics industry.
Marshall on Maintenance
Maintenance is not optional in manufacturing. It’s a profit center, driving productivity and uptime while reducing overall repair costs.
Lachance on CMMS
The Lachance on CMMS blog is about current maintenance topics. Blogger Paul Lachance is president and chief technology officer for Smartware Group.
Material Handling
This digital report explains how everything from conveyors and robots to automatic picking systems and digital orders have evolved to keep pace with the speed of change in the supply chain.
Electrical Safety Update
This digital report explains how plant engineers need to take greater care when it comes to electrical safety incidents on the plant floor.
IIoT: Machines, Equipment, & Asset Management
Articles in this digital report highlight technologies that enable Industrial Internet of Things, IIoT-related products and strategies.
Randy Steele
Maintenance Manager; California Oils Corp.
Matthew J. Woo, PE, RCDD, LEED AP BD+C
Associate, Electrical Engineering; Wood Harbinger
Randy Oliver
Control Systems Engineer; Robert Bosch Corp.
Data Centers: Impacts of Climate and Cooling Technology
This course focuses on climate analysis, appropriateness of cooling system selection, and combining cooling systems.
Safety First: Arc Flash 101
This course will help identify and reveal electrical hazards and identify the solutions to implementing and maintaining a safe work environment.
Critical Power: Hospital Electrical Systems
This course explains how maintaining power and communication systems through emergency power-generation systems is critical.
Design of Safe and Reliable Hydraulic Systems for Subsea Applications
This eGuide explains how the operation of hydraulic systems for subsea applications requires the user to consider additional aspects because of the unique conditions that apply to the setting
click me