Vacuum Systems for Additive Manufacturing and 3D printing
Additive Manufacturing, more commonly known as 3D Printing, is also referred to as Rapid Prototyping (RP), Direct Digital Manufacturing (DDM) and Additive Fabrication (AF).
It is a revolutionary manufacturing method for producing parts with complex geometries, low-volume manufacturing runs and prototypes. This method replaces traditional and typically more labor-intensive manufacturing methods, including subtractive manufacturing (cutting away and removing unneeded material) and forming and casting.
The additive manufacturing process generally involves adding thin layers of powdered material and using devices such as high-powered lasers to sinter or melt each layer to fuse it to the part being constructed. This process is based on CAD 3D models that are used as a guide or map for the process. The materials used in additive manufacturing can range from starch to photopolymer resins (polymer) changes properties when exposed to light) to thermoplastics to metals, such as aluminum, titanium, stainless steel, Inconel alloys, and others.
The importance of a Dust Hazard Analysis (DHA):
Whether the powders or materials used are metal or nonmetal, it is imperative that anyone considering using additive manufacturing perform a dust hazards analysis (DHA) on the process to determine the hazards involved and how those hazards will be managed. This analysis is a requirement for any combustible dusts used in the manufacturing process. The 3D printers used in additive manufacturing usually require cleaning after the process is completed. Control of fugitive dust emissions and housekeeping outside of (and around) the 3D printing equipment must also be considered.
There are many approaches to conducting a DHA, and the Annex of NFPA 652 provides one example. A main focal point of NFPA 652 is the requirement for facilities processing or handling particulate solids to perform a dust hazard assessment (DHA). NFPA will also be addressing the fire, flash-fire, and explosion hazards associated with additive manufacturing using metal powders. NFPA 484: Standard for Combustible Metals (2015) is currently being revised, and it is expected that the next edition will include a section on additive manufacturing involving metal powders
Vacuum systems for use in Additive Manufacturing and 3D Printing:
The 3D printers used in additive manufacturing usually require cleaning after the process is completed. Most cleaning protocols include vacuuming with a portable vacuum system. Vacuum cleaning is also required to handle fugitive dust and for housekeeping near the additive manufacturing process.
Tiger-Vac manufactures a complete line of Mini Immersion “Wet Mix” separators for additive manufacturing and 3D Printing. Our Mini Immersion systems are available in electrically operated or pneumatic (air operated) versions. We offer several equipment protection levels such as Dust Ignition Protected as well as Explosion Proof / Dust Ignition Proof (Hazloc).
Our Mini Immersion “Wet Mix” vacuum systems are designed for the recovery and neutralization of combustible metal dusts in a liquid bath. This includes: aluminum, magnesium, tantalum, titanium and zirconium. These immersion systems comply with NFPA Standard 484 and meet NFPA requirements for the recovery of combustible metal dusts.
NFPA Standards used by Tiger-Vac
Tiger-Vac uses several NFPA standards as guidelines for the design and fabrication of its explosion proof / dust ignition proof vacuum systems. It is true that compliance with NFPA standards is voluntary. However, OSHA relies heavily on the NFPA when developing its own standards. And both courts of appeals and the Occupational Safety and Health Review Commission have ruled that OSHA’s main housekeeping standard, 1910.22, applies to combustible dust hazards.
NFPA 484: Standard for Combustible Metals
This standard applies to the production, processing, finishing, handling, recycling, storage, and use of all metals and alloys that are in a form that is capable of combustion or explosion, as well as to operations where metal or metal alloys are subjected to processing or finishing operations that produce combustible powder or dust. Particluar attention is needed for aluminum, magnesium, tantalum, titanium and zirconium and other commercial alloys.
Important note for Vacuum Systems Intended for the Recovery of Metal Dust
In addition to NRTL certification for use in Class II, Group E hazardous locations, the recovery of metal dust may require a dust ignition proof vacuum with additional safeguards. Certain metal dusts may have characteristics that require safeguards beyond those required for atmospheres containing the dusts of aluminum, magnesium, and their commercial alloys. For the recovery of metal dust in quantities greater than 5 lbs. (2.2 Kg), Tiger-Vac recommends an immersion (wet mix) separator to neutralize the metal dust.
NFPA 652: Standard on the Fundamentals of Combustible Dust
Every year, destructive and deadly dust-related fires and explosions affect a wide range of industries around the globe. In the United States alone, 50 combustible dust accidents occurred between 2008 and 2012. To manage the dust-related fire, flash fire, and explosion hazards in industries that use dust collection and handling equipment, or have processes that may generate combustible dust, NFPA introduces the first-time NFPA 652: Standard on the Fundamentals of Combustible Dust. This important new Standard serves a wide variety of industries including chemical, wood processing, metals, and agricultural.
In addition to providing new general requirements for managing combustible dust fire and explosion hazards, NFPA 652 directs users to NFPA's appropriate industry- or commodity-specific standards, such as NFPA 61: Prevention of Fires and Dust Explosions in Agricultural and Food Processing Facilities; NFPA 484: Combustible Metals; NFPA 654: Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids; and NFPA 664: Prevention of Fires and Explosions in Wood Processing and Woodworking Facilities.
What does it mean for a vacuum system to be NFPA-652 compliant?
NFPA 652 requires all facilities handling combustible dust, even in NON-Classified environments, to use vacuum systems that meet very specific design requirements as laid out in NFPA 652 Section 8.4.2.2.
The standard identifies 7 specific requirements:
The materials of construction must be conductive, except in a few specific circumstances.
Hoses must be conductive or static dissipative.
All conductive components, including wands and attachments, must be bonded and grounded.
Dust-laden air must not pass through the fan or blower.
Electrical motors must not be in the dust-laden air stream unless listed for Class II, Division I, locations.
Paper filter elements aren’t allowed for picking up liquids or wet materials.
Vacuum systems used for metal dusts must meet the requirements of NFPA 484, which is the standard for combustible metals.
What is an Explosion Proof Vacuum System?
An explosion proof vacuum system is a vacuum system that is capable of preventing the ignition of a specified gas or vapor and that operates at such an external temperature that a surrounding flammable atmosphere will not be ignited. To be considered as being explosion proof, a vacuum system must be certified by a Nationally Recognized Testing Lab (NRTL).
What is a Dust Ignition Proof Vacuum System?
A dust ignition proof vacuum system is a vacuum system that is protected in a manner that excludes dusts and does not permit arcs, sparks, or heat otherwise generated or liberated inside of the electrical enclosure to cause ignition of exterior accumulations or atmospheric suspensions of a specified dust on or near the vacuum system. To be considered as being dust ignition proof, a vacuum system must be certified by a Nationally Recognized Testing Lab (NRTL).
Nationally Recognized Testing Lab (NRTL)
OSHA created the NRTL program to ensure that certain types of equipment be tested and certified for their safe use in the workplace. A Nationally Recognized Testing Laboratory (NRTL) is a private-sector organization that OSHA has recognized as meeting the legal requirements in 29 CFR 1910.7 to perform testing and certification of products using consensus-based test standards. An organization must have the necessary capability both as a product safety testing laboratory and as a product certification body to receive OSHA recognition as an NRTL. To find out more about the OSHA NRTL program, please follow this link to the OSHA website: https://www.osha.gov/dts/otpca/nrtl/nrtllist.html
What is an ATEX Vacuum System?
ATEX refers to the European safety standards. is an abbreviation/acronym of “ATmosphères EXplosibles” (Explosive Atmospheres). An ATEX vacuum system is a vacuum system which is specifically designed, built and certified for use in Potentially Explosive Atmospheres also known as Hazardous Areas. Hazardous Areas are working areas endangered by the presence of flammable gases, vapors, mists or dusts that have the potential to be explosive in presence of oxygen and a source of ignition.
The European Community (EC) has adopted two directives concerning Potentially Explosive Atmospheres called ATEX directives.
Directive 99/92/EC also known as ATEX 137 or the ATEX "Worker safety Directive", to classify the zones where the vacuum system is used based on the flammable materials present in the zone.
Directive 2014/34/EU, (also known as ATEX 94/9/EC, ATEX 95 or ATEX 100a or the ATEX "Equipment" Directive), to inform customers with regards to the vacuum system certification and level of protection.
How to choose the right Hazloc Vacuum System for your application?
To choose the right explosion proof / dust ignition proof vacuum system for your application, you will have to identify the material to be recovered and determine the classification of the hazardous location (Hazloc) where the vacuum system will be used.
Identifying the material to be recovered
The first step in selecting the correct Hazloc Vacuum System is to identify the material to be recovered. “Dry only” vacuum systems that are designed to recover dust or dry material only. “Wet and dry” vacuum systems that are designed to recover dry material or liquids. Vacuum systems are not designed to recover mud (mixture of liquid and soil). Mud would obstruct filters and decrease the performance of the vacuum system.
Flammable materials can be gaseous, liquid or solid. To work in hazardous locations where flammable materials are present, Tiger-Vac recommends an explosion proof vacuum system that is Legally Certified.
Tiger-Vac has developed Explosion Proof industrial vacuum systems to be able to recover specific materials such as flammable liquids (such as jet fuel and solvents) and Dust Ignition Proof vacuum systems for the recovery of combustible and conductive dust (such as metal powder and gun powder).
Definition of Combustible Dust
Combustible Dust. Dust particles that are 500 microns or smaller (material passing a U.S. No. 35 Standard Sieve as defined in ASTM E 11-09, Standard Specification for Wire Cloth and Sieves for Testing Purposes) and present a fire or explosion hazard when dispersed and ignited in air.
Classifications of Hazardous Locations According to NFPA 70
Locations shall be classified depending on the properties of the flammable gas, flammable liquid–produced vapor, combustible liquid–produced vapors, combustible dusts, or fibers/flyings that may be present, and the likelihood that a flammable or combustible concentration or quantity is present. Each room, section, or area shall be considered individually in determining its classification
Class II and Class III (Dust) locations
Class II Locations
Class II locations are those that are hazardous because of the presence of combustible dust.
Class II, Division 1
A Class II, Division 1 location is a location:
In which combustible dust is in the air under normal operating conditions in quantities sufficient to produce explosive or ignitable mixtures, or
Where mechanical failure or abnormal operation of machinery or equipment might cause such explosive or ignitable mixtures to be produced, and might also provide a source of ignition through simultaneous failure of electrical equipment, through operation of protection devices, or from other causes, or
In which Group E combustible (metal) dusts may be present in quantities sufficient to be hazardous. Dusts containing magnesium or aluminum are particularly hazardous, and the use of extreme precaution is necessary to avoid ignition and explosion.
Class II, Division 2
A Class II, Division 2 location is a location in which combustible dust due to abnormal operations may be present in the air in quantities sufficient to:
Produce explosive or ignitable mixtures; or
Where combustible dust accumulations are present but are normally insufficient to interfere with the normal operation of electrical equipment or other apparatus, but could as a result of infrequent malfunctioning of handling or processing equipment become suspended in the air; or
In which combustible dust accumulations on, in, or in the vicinity of the electrical equipment could be sufficient to interfere with the safe dissipation of heat from electrical equipment, or could be ignitable by abnormal operation or failure of electrical equipment.
Class III Locations
Class III locations are those that are hazardous because of the presence of easily ignitable fibers or where materials producing combustible flyings are handled, manufactured, or used, but in which such fibers/flyings are not likely to be in suspension in the air in quantities sufficient to produce ignitable mixtures.
Class III, Division 1
A Class III, Division 1 location is a location in which easily ignitable fibers/flyings are handled, manufactured, or used. Such locations usually include some parts of rayon, cotton, and other textile mills; combustible fibers/flyings manufacturing and processing plants; cotton gins and cotton-seed mills; flax-processing plants; clothing manufacturing plants; woodworking plants; and establishments and industries involving similar hazardous processes or conditions.
Class III, Division 2
A Class III, Division 2 location is a location in which easily ignitable fibers/flyings are stored or handled other than in the process of manufacture.
Material Groups (Dust)
Class II, Group E
Atmospheres containing combustible metal dusts, including aluminum, magnesium, and their commercial alloys, or other combustible dusts whose particle size, abrasiveness, and conductivity present similar hazards in the use of electrical equipment.
Class II, Group F
Atmospheres containing combustible carbonaceous dusts such as coal, carbon black, charcoal, and coke dusts.
Class II, Group G
Atmospheres containing combustible dusts not included in Group E or Group F, including flour, grain, wood, plastic, and chemicals.