1. NAFA Guide To Air Filtration
Fifth Edition
Industrial Contaminant Air
Filtration Control Systems
presented by the
National Air Filtration Association
Industrial contaminant control can be a large part of your filter business. Usually, you should partner with an experienced Equipment Manufacturer and or Contractor who is familiar with source capture Technology, hoods and industrial contaminants.

2. Metal Working Fluids Spinning chuck of a metalworking
Metal working machines – sometimes called CNC machines – are in use in many plants where machined parts are part of a production process. These machines use 4 different types of cooling oil to keep the temperature of cutting bits cool. Fluids can be straight, soluble, semi-synthetic or synthetic oils. Expansion of parts due to heat can destroy the accuracy of machining that has to fit with close tolerances. This cooling process evaporates the cooling fluid and turns it into an aerosol mist, vapor or smoke which must be captured.
Spinning chuck of a metalworking
machine aerosolizes cooling fluids

3. Reason for Capture Fluids may be hazardous to people
Fluids may damage interior of facility/machine parts
Exhausting to outside may be illegal
Fluids can be captured and
reused
There are many reason to capture the aerosolized metalworking fluid including the hazard it posses to plant workers. Some metalworking fluids cause skin irritation, asthma, hypersensitive pneumonitis, and they may be carcinogenic. In addition, these fluids can destroy computer equipment that are part of the metalworking machine and other plant equipment. Clean fluid can be reused when captured.

4. Challenges of Oil Mists and Smokes Collection
Page 15.2 details the sizes and challenges of collecting oil mists and smokes.

5. Mist Removal Equipment
Media-type mist removal equipment utilize several stages to remove oil mist. The first stage usually involves a simple change of air direction or bafffle filter to knock out larger particles that then drain into a sump on the bottom of the machine. The second stage usually involves a pocket filter specially designed to collect oil mist ( Oliophobic) and suspended in the vertical position so that coalesced particles drain back into the sump. Final stages may involve HEPA or carbon filters depending on whether the air is to be recirculated back into the facility or not. Centrifugal separators have rotating drums that cause the mist particles to impinge on the outer housing of the unit where they drain into a sump.
Media type
Centrifugal type

6. Mist and Smoke Removal
Electrostatic precipitation works well for smoke and mist removal
Just like ESP’s, industrial electrostatic precipitation involves ionizing particles and mist as they enter the unit and then collecting them on oppositely charged plates in the collector section. The only difference is the industrial mist and smoke collectors utilize special ionizers and plates that can process wet contaminants, and position the plates in the vertical position for oil drainage back into a sump. Do not use this type of collection system if Metal Particles are captured in the oil mist, otherwise you will cause the system to Short.) Also consult the MSDS Sheets for the “Oil Flash Point”, do not use this type of system where fluids have “Low Flash/ Explosive limits” or with less than 5% water misible content.

7. Welding Smoke Removal Welding smoke can be
completely removed with correct design of a source capture hood, then filtered through
Media or ESP air cleaners
Welding fumes contain many contaminants and dangerous compounds. Welding smoke removal requires a well-designed source capture hood like the one above attached to a ducted arm. Do not use ESP where grinding fines may be captured

8. Cyclone Dust Separator
Afterfilters – usually
placed back inside the
facility
Dust separators (formally called dust collectors) are used in many factories for the moving of process goods such as agricultural grains, or the removal of unwanted waste product such as sawdust in furniture factories. The size and type of dust separator used is determined by the type of substance moved/removed and the number of pickup points (source removal points) on the system. Traditionally, cyclone dust separators are used to remove wood chips and coarse dust from woodworking operations. Cyclone collectors cause larger particles to be spun to the bottom of the collector while clean air exits up through the center of the funnel and is either exhausted or sent through afterfilters and recirculated back into the plant air. As is the case with all dust separation equipment, makeup air must be used to replace air withdrawn from the facility by this equipment.
Many dust are Explosive by nature, careful precautions are necessary these applications with very strict Standards that must be complied with, therefore it is necessary to consult the equipment Manufacture, National Fire Codes, Building Codes and the local authority having Jurisdiction proceeding with any type of dust collector system.

9. Baghouse Separator
Baghouse dust separation equipment is an older technology utilizing the baghouse, a dust collection hopper, tubesheets which are round wire cages covered with a dust collection fabric, and a plenum to return the clean air. Baghouse separators come in either a shaker type, which has a manual shaking mechanism tht shakes the collected dust off of the outside of the bags, a reverse pulse baghouse that blows a blast of air back through the bags to removve collected dust, and reverse pulse collectors that use a synchronized reverse blast of compressed air while the collector remains running.

10. Jet Pulse Separator
Cartridge collectors are used when space is at a premium or when high efficiency particulate removal/ capture is desired. They are all jet pulse cleanable and utilize cartridge filters instead of bags. Cartridge collectors are good for material removal that is reusable such as powders, but do not use them on any viscous/ wet contaminants.

11. Summary Metal working fluids are used to cool the machining process
Fluids can be straight, soluble, semi-synthetic or synthetic oils.
Mists are generally larger particles than smokes
Mists and smokes can be collected by media, centrifugal or electrostatic means and returned to the machine for reuse.

12. Summary Welding smoke is a mixture of fine particles and gases
Source capture on collectors depends on properly designed capture hoods
Cyclone, shaker & reverse pulse and jet pulse are all styles of dust separation equipment
Cartridge collectors are popular where space is limited

13. Sample Questions Q. Metal Working Fluids are used to?
Answer: To cool, lubricate and clean production parts
Q. A typical Oil Mist electrostatic precipitator has what sections (inlet to outlet)?
Answer: Baffle section
Ionizer Section
Collecting Section
Fan section
Optional After filter

14. Sample Questions
Dust Separation is used for two objectives? Answer: 1. Recover valuable product from plant processes that generate dust 2. Clean air to stay in compliance with OSHA & EPA requirements A baghouse is composed of? Answer: house, hopper(s), tubesheet and plenum.

15. Thank you.
Other Questions?