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. ATEX is an abbreviation/acronym of “ATmosphères EXplosibles” (Explosive Atmospheres). An ATEX vacuum cleaner 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.
What is an “intrinsically safe” vacuum system?
The term “intrinsically safe vacuum system” commonly refers to vacuum cleaners that operate without electricity and have no moving parts. Tiger-Vac uses a venturi to transform compressed air into powerful suction. The compressed air cools the venturi as the vacuum system is running. Since there are no moving parts, the vacuum system can run continuously without any friction or wear. Tiger-Vac explosion proof vacuum systems are also designed to be grounded during use. Any statically electricity that is produced while vacuum is dissipated through the vacuum system and is discharged to ground.
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 Flammable Liquids
Flammable Liquid. A flammable liquid having a flash point below 38°C (100°F), or a flammable liquid whose temperature is above its flash point, or a Class II combustible liquid that has a vapor pressure not exceeding 276 kPa (40 psia) at 38°C (100°F) and whose temperature is above its flash point.
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 I Locations
Class I locations are those in which flammable gases, flammable liquid–produced vapors, or combustible liquid–produced vapors are or may be present in the air in quantities sufficient to produce explosive or ignitable mixtures. Class I locations shall include those specified in 500.5(B)(1) and (B)(2).
Class I, Division 1, Hazardous Locations
A Class I, Division 1, hazardous locations is a location in which ignitable concentrations of flammable gases, flammable liquid–produced vapors, or combustible liquid–produced vapors can exist under normal operating conditions. Or, in which ignitable concentrations of such flammable gases, flammable liquid–produced vapors, or combustible liquids above their flash points may exist frequently because of repair or maintenance operations or because of leakage. It also includes locations in which breakdown or faulty operation of equipment or processes might release ignitable concentrations of flammable gases, flammable liquid–produced vapors, or combustible liquid–produced vapors and might also cause simultaneous failure of electrical equipment in such a way as to directly cause the electrical equipment to become a source of ignition.
Examples of Class I, Division 1 Hazardous Locations
Class I, Division 1 Hazardous Locations usually include the following locations:
- Where volatile flammable liquids or liquefied flammable gases are transferred from one container to another.
- Interiors of spray booths, and areas in the vicinity of spraying and painting operations where volatile flammable solvents are used.
- Locations containing open tanks or vats of volatile flammable liquids.
- Drying rooms or compartments for the evaporation of flammable solvents.
- Locations containing fat- and oil-extraction equipment using volatile flammable solvents
- Portions of cleaning and dyeing plants where flammable liquids are used.
- Gas generator rooms and other portions of gas manufacturing plants where flammable gas may escape.
- Inadequately ventilated pump rooms for flammable gas or for volatile flammable liquids.
- The interiors of refrigerators and freezers in which volatile flammable materials are stored in open, lightly stoppered, or easily ruptured containers.
- All other locations where ignitable concentrations of flammable vapors or gases are likely to occur during normal operations
Class I, Division 2 Hazardous Locations
A Class I, Division 2 location is a location:
- In which volatile flammable gases, flammable vapors, or combustible vapors are handled, processed, or used, but in which the liquids, vapors, or gases will normally be confined within closed containers or closed systems from which they can escape only in case of accidental rupture or breakdown of such containers or systems or in case of abnormal operation of equipment.
- In which ignitable concentrations of flammable gases, flammable liquid–produced vapors, or combustible liquid–produced vapors are normally prevented by positive mechanical ventilation and which might become hazardous through failure or abnormal operation of the ventilating equipment, or
- That is adjacent to a Class I, Division 1 location, and to which ignitable concentrations of flammable gases, flammable liquid–produced vapors, or combustible liquid–produced vapors above their flash points might occasionally be communicated unless such communication is prevented by adequate positive-pressure ventilation from a source of clean air and effective safeguards against ventilation failure are provided.
The Class I, Division 2 classification usually includes locations where volatile flammable liquids or flammable gases or vapors are used but that, in the judgment of the authority having jurisdiction, would become hazardous only in case of an accident or of some unusual operating condition. The quantity of flammable material that might escape in case of accident, the adequacy of ventilating equipment, the total area involved, and the record of the industry or business with respect to explosions or fires are all factors that merit consideration in determining the classification and extent of each location.
Material Groups (Gas)
Class I Group Classifications
Class I, Group A Atmospheres containing acetylene.
Class I, Group B Atmospheres containing hydrogen.
Class I, Group C Atmospheres containing ethylene.
Class I, Group D
Atmospheres containing acetone, benzene, butane, ethane, ethanol, ether, gasoline, heptane, hexane, isoprene, liquified petroleum gas, methyl ethyl ketone, octane, propane, styrene, toluene, vinyl chloride, xylenes.
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.
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 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.
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.
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.