What is a Dust Ignition Protected Vacuum System?
A dust ignition protected vacuum system is a vacuum system that is enclosed in a manner that excludes dusts and does not permit arcs, sparks or heat otherwise generated or liberated inside of the enclosure to cause ignition of exterior accumulations or atmospheric suspensions of a specified dust on, or in the vicinity of, the vacuum system. To be considered as being dust ignition protected, a vacuum system must be certified by a Nationally Recognized Testing Lab (NRTL).
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 cleaner 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 cleaner. 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. ATEX 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.
How to choose the right Hazloc Vacuum System for the recovery of combustible dust?
To choose the right Hazloc 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.
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 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 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. 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.
Material Groups (Dust)
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.
NFPA Standards used by Tiger-Vac
Tiger-Vac uses several NFPA standards as guidelines for the design and fabrication of its vacuum systems for combustible dust recovery. 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 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 outlined in NFPA 652 Section 8.4.2.2.1.7.
The standard identifies 7 specific requirements. Tiger-Vac Division 2 Industrial Vacuum Systems meet or exceed all of these 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.