- Applications
- Industrial Filtration
Industrial Filtration: Technologies, Applications & Selection
Industrial filtration is not one technology or one product category. It is a broad discipline focused on controlling contaminants within air, gas, hydraulic, dust-collection and liquid systems so equipment and processes can operate as intended.
For industrial distributors, that breadth creates both an opportunity and a challenge.
A customer asking for a replacement filter may appear to have a simple product need. But the real problem could involve contamination levels, filter media, pressure drop, operating temperature, fluid compatibility, system location, airflow or flow rate, required efficiency, maintenance intervals or an application that has changed since the original filter was specified.
Understanding those variables helps move the conversation beyond simply matching a part number.
The better question is: What is the filtration system supposed to accomplish?
That question applies whether the customer is filtering compressed air, hydraulic fluid, airborne dust or process liquid.
What Is Industrial Filtration?
Industrial filtration is the removal or control of unwanted particles, liquids, aerosols, vapors or other contaminants from a process stream or operating environment.
The exact objective depends on the system. A compressed-air filter may help remove solid particles, condensed water or oil aerosols. A hydraulic filter may be used to control particulate contamination circulating through a fluid-power system. Dust-collection filtration separates airborne particulate from an air stream. Liquid filtration may remove suspended solids from process fluids.
Although the equipment and filter designs can be very different, the underlying selection process has common elements:
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What contaminant must be controlled?
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What size is the contaminant?
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How efficiently must it be removed?
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What flow must the system handle?
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What pressure and temperature will the filter experience?
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What media is compatible with the application?
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How much pressure drop is acceptable?
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What happens as the filter loads?
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How will the filter be monitored and changed?
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What would happen if filtration performance deteriorated?
These are application questions—not simply catalog questions.
Four Major Areas of Industrial Filtration
KELTEC's expanding filtration focus can be understood through four major industrial filtration disciplines.
Compressed-Air Filtration
Compressed air can contain solid particles, liquid water, water aerosols, lubricant aerosols and, depending on the system and application, hydrocarbon vapor.
Different contaminants require different treatment technologies. Particulate filters are designed around solid-particle removal. Coalescing filters are commonly used to capture liquid aerosols by bringing fine droplets together so they can be separated and drained. Additional treatment may be required where oil vapor or especially demanding air-quality requirements are involved.
The filtration system also has to work with the rest of the compressed-air treatment train, including separators, dryers and drains.
Pressure drop is especially important because restrictions in a compressed-air system can increase the pressure the compressor must produce and therefore affect energy consumption.
For a distributor, recommending a compressed-air filter therefore requires more information than pipe size alone.
Hydraulic Filtration
Hydraulic systems rely on fluid to transmit power while also lubricating and protecting system components.
Contamination can enter during manufacturing, maintenance, component wear, fluid addition or through exposure to the operating environment. Once present, particles can circulate throughout the system.
Hydraulic filtration strategies can involve different filter locations depending on the system design, including pressure, return, suction and offline or kidney-loop filtration.
The right approach depends on equipment sensitivity, contamination-control requirements, system flow, operating pressure, fluid characteristics, operating environment, filter location, desired cleanliness and maintenance strategy.
A filter that physically fits is not automatically the right filter for the hydraulic system. That distinction is critical when distributors are helping customers replace an element, troubleshoot shortened filter life or address recurring contamination.
Dust Filtration
Industrial dust collection deals with particulate suspended in an air stream.
Applications vary widely - from relatively coarse material to much finer particulate - and filtration requirements depend on the characteristics of the dust, equipment, process and operating environment.
Common technologies may incorporate bags, cartridges or other filter-media configurations. Key considerations can include dust characteristics, particle loading, airflow, media selection, collection efficiency, differential pressure, cleaning method, temperature, moisture, process conditions and filter life.
A replacement dust collector filter therefore should not be selected solely because its dimensions resemble the existing filter. Media and application conditions matter.
Liquid Filtration
Industrial liquid filtration covers an equally broad range of applications.
Depending on the process, filtration may be used to protect downstream equipment, improve fluid cleanliness, remove suspended contaminants, recover material or help maintain process quality.
Bag and cartridge filtration are common approaches, but neither is universally better. Selection depends on factors such as contaminant type and loading, desired retention, viscosity, flow, pressure, temperature, fluid compatibility and changeout requirements.
Pressure drop is again part of the equation. Filter characteristics, flow and fluid properties all affect the resistance created by the filtration system.
That is why liquid filtration should be specified around the actual application rather than a filter dimension alone.
The Filtration Principles Connecting All Four Systems
1. Identify the Contaminant
Start with what needs to be removed: solid particulate, liquid water, oil aerosol, hydrocarbon vapor, wear debris, process solids, airborne dust or another contaminant. Without understanding the contaminant, micron rating alone provides very little context.
2. Understand Particle or Droplet Size
Particle size matters, but a micron number does not fully describe filter performance. Two filters displaying the same nominal micron rating may perform differently because of their media, construction, efficiency definitions and test methods.
3. Determine Required Efficiency
The relevant question is not simply, “What micron is the filter?” It is, “How efficiently does the filter capture the contaminant size that matters to this system?”
4. Account for Flow
Filters create resistance. A filter must provide the required contaminant control while handling the application's airflow or liquid flow without creating unacceptable restriction.
5. Evaluate Pressure and Temperature
Filter housings, seals, media and elements must all be appropriate for the application's operating conditions. Pressure, temperature and chemical compatibility cannot be assumed from physical dimensions.
6. Consider Differential Pressure
As contamination accumulates, resistance generally increases. Differential pressure can therefore provide valuable information about filter condition, but its significance depends on the type of system and filter involved.
7. Think Beyond Initial Purchase Price
The lowest-cost filter is not always the lowest-cost filtration solution. A useful evaluation can include expected service life, energy implications, equipment protection, maintenance frequency, downtime, disposal, labor, replacement availability and system reliability.
Questions Distributors Should Ask Before Recommending a Filter
Before selecting or cross-referencing an industrial filter, obtain as much application information as possible.
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What equipment or system is the filter used in?
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What is being filtered?
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What contaminant needs to be removed?
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What is the required flow?
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What are the normal and maximum operating pressures?
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What are the operating temperatures?
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What filtration efficiency or cleanliness level is required?
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What is the existing filter or housing?
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Why is the filter being replaced?
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Has the application changed?
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Is the customer experiencing abnormal pressure differential or unusually short filter life?
A recurring filtration problem may indicate that replacing the existing element with another identical element will not solve the customer's underlying problem.
When the Application Requires More Than a Standard Filter
Standard filtration products solve a large number of industrial applications. Others require something different.
Examples may include unusual dimensions, uncommon media requirements, challenging operating conditions, unique end configurations, legacy equipment or a filtration requirement that cannot be adequately addressed with an existing catalog product.
