Tag Archives: oil mist filtration

Industrial manufacturing processes generate different types of airborne contaminants, from coarse dust and fine particulate to welding fumes, oil mist, smoke, and vapours. Because these contaminants behave differently in an air stream, no single filtration technology is suitable for every industrial application.

Choosing the right industrial air filtration systems requires understanding the contaminant, particle characteristics, concentration, airflow, temperature, process conditions, and required level of filtration.

This guide explains the major industrial air filters, fume filtration systems, and dust filtration systems, and where each technology is typically used.

Key Takeaways

1. Different industrial contaminants require different filtration technologies.
2. Baghouse and cartridge collectors are commonly used for industrial dust collection.
3. Fume filtration systems are designed for fine particulate generated by processes such as welding.
4. Oil and coolant mist require mist-specific filtration rather than conventional dry dust filters.
5. HEPA filtration can provide high-efficiency particulate filtration when the application requires it.
6. Wet scrubbers can be suitable for certain particulate and gaseous contaminants.
7. Filter selection should consider both filtration efficiency and the complete extraction system.

What Are Industrial Air Filtration Systems?

Industrial air filtration systems are engineered systems designed to remove airborne contaminants generated by manufacturing and industrial processes.

A typical system may include:

1. Capture hood or enclosure
2. Ductwork
3. Pre-filtration or separation
4. Main filtration stage
5. Blower
6. Dust or contaminant collection
7. Control and monitoring equipment

The filtration equipment is only one part of the overall system. If contaminants are not captured effectively at the source or the airflow is inadequate, even a high-efficiency filter may not provide the expected results.

Why Filter Selection Matters

Industrial contaminants can vary significantly.

For example, grinding may generate relatively heavy metal particles, while welding can produce much finer fumes. CNC machining may generate an aerosol of oil or coolant droplets rather than dry particulate.

The filtration technology therefore needs to match the contaminant.

Important selection factors include:

1. Particle size
2. Dust loading
3. Contaminant concentration
4. Airflow
5. Temperature
6. Moisture
7. Chemical characteristics
8. Filter media compatibility
9. Required filtration efficiency
10. Pressure drop
11. Operating hours
12. Maintenance requirements

Major Industrial Air Filtration Technologies

1. Baghouse Dust Collectors

Baghouse collectors use fabric filter bags to separate particulate from an air stream.

Contaminated air enters the collector and passes through the filter bags. Dust accumulates on the filter surface while cleaner air passes through.

Baghouse systems are commonly used for applications involving:

1. Grinding
2. Material handling
3. Foundries
4. Mineral processing
5. Wood processing
6. Heavy manufacturing
7. High dust loading

Their ability to handle substantial dust loads makes them an important category of industrial dust filtration systems.

2. Cartridge Dust Collectors

Cartridge collectors use pleated filter elements.

The pleated construction provides a large filtration area within a relatively compact housing, making cartridge systems suitable where installation space is limited.

They are commonly considered for:

1. Fine dry dust
2. Metalworking
3. Grinding
4. Cutting
5. Welding
6. Powder handling

Cartridge collectors can also incorporate automatic cleaning systems to remove accumulated dust from the filter surface.

3. Welding Fume Filtration Systems

Welding generates fine particulate that can remain airborne for extended periods.

Fume filtration systems are designed specifically for applications such as:

1. MIG/MAG welding
2. TIG welding
3. Arc welding
4. Robotic welding
5. Plasma cutting
6. Thermal cutting

Source capture is particularly important for welding because capturing the fume close to the welding operation prevents it from dispersing throughout the workspace.

Depending on the application, systems may use extraction arms, hoods, enclosures, portable extractors, or centralized extraction.

4. Oil and Coolant Mist Filtration

Oil mist and coolant mist generated during CNC machining are aerosols rather than conventional dry dust.

These applications require filtration technologies designed to separate liquid droplets from the air stream.

Mist collectors are commonly used for:

1. CNC turning
2. Milling
3. Grinding
4. Drilling
5. High-speed machining
6. Metalworking

The collector may incorporate multiple filtration stages to capture progressively finer droplets.

Using a dust collector designed for dry particulate does not automatically make it suitable for oil or coolant mist.

5. HEPA Filtration

HEPA filters are designed for high-efficiency removal of very small airborne particles.

They can be incorporated into industrial air filtration systems when the application requires a high level of particulate filtration.

Potential applications include:

1. Fine particulate control
2. Final filtration
3. Controlled production environments
4. Specialized manufacturing processes
5. Supplementary filtration stages

However, HEPA filters are not automatically the best choice for every industrial dust application.

A heavily loaded process may require a pre-filter or primary dust collector upstream to prevent excessive loading of the HEPA stage.

6. Electrostatic Filtration

Electrostatic precipitators use electrical charges to collect particles from an air stream.

They can be used in certain applications involving:

1. Smoke
2. Fine particulate
3. Oil mist
4. Process emissions

Electrostatic systems can be attractive where specific contaminant characteristics and operating conditions make them appropriate.

However, their suitability depends on the application and the properties of the contaminant.

7. Wet Scrubbers

Wet scrubbers use a liquid to capture or absorb contaminants from an air stream.

Depending on their design, scrubbers can be used for certain:

1. Dust
2. Chemical contaminants
3. Acid gases
4. Process emissions
5. Hot or moisture-laden streams

Wet scrubbers can be particularly useful where dry filtration is unsuitable because of contaminant characteristics or process conditions.

They also introduce additional considerations such as wastewater handling, corrosion, liquid management, and maintenance.

8. Activated Carbon Filtration

Activated carbon is primarily used to adsorb certain gases, vapours, and odorous compounds.

It can be incorporated into a multi-stage filtration system when the process produces contaminants that cannot be adequately controlled through particulate filtration alone.

Activated carbon is therefore fundamentally different from a conventional dust filter.

Comparing Industrial Air Filters

Technology	Typical Contaminant	Common Application
Baghouse	Dry particulate, high dust loading	Grinding, material handling
Cartridge	Fine dry dust and particulate	Metalworking, powder processing
Fume filtration	Welding and process fumes	Welding and thermal processes
Mist collector	Oil and coolant aerosols	CNC machining
HEPA	Very fine particulate	Final/high-efficiency filtration
Electrostatic	Fine particulate, smoke, some mist	Process emissions
Wet scrubber	Particulate and selected gases	Chemical/process applications
Activated carbon	Vapours and certain gases	Odour and VOC-related applications

Dust Filtration Systems

Dust filtration systems are primarily designed to remove solid particulate from industrial air.

The appropriate technology depends heavily on the characteristics of the dust.

Coarse Dust

Coarser particles may be relatively easy to separate using appropriate mechanical filtration or pre-separation.

Fine Dust

Fine particles require appropriately selected filter media and sufficient filtration area.

High Dust Loading

Processes producing large quantities of dust may require robust baghouse or cartridge collection systems with effective filter cleaning.

Abrasive Dust

Abrasive particles may require attention to collector construction, duct velocity, wear protection, and filter selection.

Fume Filtration Systems

Fumes are generally finer than conventional dust and can be generated through thermal processes.

Examples include:

1. Welding
2. Cutting
3. Brazing
4. Soldering
5. Thermal processing

For these applications, the capture method is just as important as the filter.

A welding fume extractor positioned close to the source can prevent the fume from entering the surrounding workplace before filtration occurs.

Filtration Efficiency vs System Performance

A common mistake is to select filtration equipment based only on the filter’s efficiency rating.

Actual system performance also depends on:

Capture Efficiency

Can the system capture the contaminant before it escapes the source?

Airflow

Is sufficient airflow maintained at the extraction point?

Ductwork

Does the duct system transport contaminated air effectively?

Filter Loading

Does accumulated material cause excessive pressure drop?

Cleaning

Can the filter be cleaned effectively during operation?

Maintenance

Are filters, seals, blowers, and other components maintained properly?

A highly efficient filter cannot compensate for poor source capture or inadequate airflow.

Understanding Pressure Drop

As dust accumulates on a filter, resistance to airflow generally increases.

This resistance is commonly monitored through differential pressure.

Increasing pressure drop can indicate:

1. Filter loading
2. Poor filter cleaning
3. Excessive dust loading
4. Blocked airflow paths
5. Filter deterioration

Monitoring pressure drop helps maintenance teams determine when investigation, cleaning, or filter replacement may be required.

How to Select the Right Industrial Air Filter

A practical selection process begins with the contaminant rather than the equipment.

Step 1: Identify the Contaminant

Determine whether the process produces:

1. Dust
2. Fume
3. Oil mist
4. Coolant mist
5. Smoke
6. Vapour
7. Gas

Step 2: Understand Its Characteristics

Evaluate:

1. Particle size
2. Concentration
3. Temperature
4. Moisture
5. Chemical composition
6. Combustibility
7. Stickiness
8. Abrasiveness

Step 3: Determine Required Airflow

Calculate the airflow required to capture and transport the contaminant effectively.

Step 4: Select the Capture Method

Consider:

1. Enclosures
2. Extraction arms
3. Hoods
4. Downdraft tables
5. Machine-integrated extraction
6. Centralized extraction

Step 5: Select Filtration Technology

Match the filter to the contaminant and process conditions.

Step 6: Evaluate Pressure Drop

The filter and complete extraction system should be evaluated for pressure loss and blower requirements.

Step 7: Plan Maintenance

Consider filter cleaning, replacement, dust discharge, access, inspection, and service requirements before finalizing the system.

Centralized vs Point-of-Use Filtration

Industrial air filtration can be configured in different ways.

Point-of-Use Filtration

A collector is installed directly at or near an individual machine or workstation.

This approach can be useful for:

1. Individual CNC machines
2. Welding stations
3. Small production areas
4. Mobile operations

Centralized Filtration

Multiple extraction points are connected to a common filtration system.

This can be suitable for:

1. Large manufacturing plants
2. Multiple fixed machines
3. Production lines
4. Facilities requiring centralized dust collection

The choice depends on the number of sources, plant layout, operating schedules, and airflow requirements.

Common Filtration Selection Mistakes

Choosing a Filter Before Identifying the Contaminant

The filter should be selected based on the material being captured, not simply on the desired equipment category.

Focusing Only on Filtration Efficiency

A filter with excellent laboratory efficiency may still perform poorly if source capture and airflow are inadequate.

Ignoring Pressure Drop

Higher resistance increases the workload on the extraction blower and can reduce system performance.

Using the Same Filter for Dust and Mist

Oil and coolant mist behave differently from dry dust and require application-specific filtration.

Undersizing the Collector

Insufficient filtration area or airflow can lead to rapid filter loading and poor extraction.

Ignoring Maintenance

Even the correct filtration technology will lose effectiveness if filters and mechanical components are not maintained properly.

Powertech’s Industrial Filtration Solutions

Powertech develops industrial pollution control systems around the characteristics of the process and contaminant.

Its product categories include:

DustBag

Industrial dust collection systems for applications generating dry particulate and process dust.

FumeKiller

Welding fume extraction and filtration systems designed for source capture of welding and thermal process fumes. Also serves as an oil mist collector for CNC manufacturing processes.

MistKiller

Water-based coolant mist collection systems for CNC machining and metalworking applications.

The appropriate system depends on the contaminant, required airflow, capture arrangement, plant layout, and operating conditions.