I have received quite a few e-mails and phone calls asking about NFPA 652: Standard on the Fundamentals of Combustible Dust, 2016 Edition and what it means to those it applies to. This article will try and break down the basic requirements which can be put into four (4) categories. PLEASE NOTE, this article assumes that you already KNOW YOUR DUST is COMBUSTIBLE.
The owner/operator of a facility with potentially combustible dust shall be responsible for the following activities:
- Determining the combustibility and explosibility hazards of materials in accordance with Chapter 5
- Identifying and assessing any fire, flash fire, and explosion hazards in accordance with Chapter 7
- Managing the identified fire, flash fire, and explosion hazards in accordance with 4.2.4
- Communicating the hazards to affected personnel in accordance with Section 9.5
Chapter 5 Hazard Identification
5.1 Responsibility
The owner/operator of a facility with potentially combustible dusts shall be responsible for determining whether the materials are combustible or explosible, and, if so, for characterizing their properties as required to support the DHA.
5.1.1 Where dusts are determined to be combustible or explosible, the hazards associated with the dusts shall be assessed in accordance with Chapter 7.
5.1.2 Where dusts are determined to be combustible or explosible, controls to address the hazards associated with the dusts shall be identified and implemented in accordance with 4.2.4.
5.2* Screening for Combustibility or Explosibility
5.2.1 The determination of combustibility or explosibility shall be permitted to be based upon either of the following:
(1) Historical facility data or published data that are deemed to be representative of current materials and process conditions
(2) Analysis of representative samples in accordance with the requirements of 5.4.1 and 5.4.3
5.2.2* Test results, historical data, and published data shall be documented and, when requested, provided to the authority having jurisdiction (AHJ).
5.2.3 The absence of previous incidents shall not be used as the basis for deeming a particulate to not be combustible or explosible.
5.2.4 Where dusts are determined to not be combustible or explosible, the owner/operator shall maintain documentation to demonstrate that the dusts are NOT combustible or explosible.
5.3* Self-Heating and Reactivity Hazards.
5.4 Combustibility and Explosibility Tests. Where combustibility or explosibility screening tests are required, they shall be conducted on representative samples obtained in accordance with Section 5.5.
5.4.1 Determination of Combustibility.
5.4.1.1 Where the combustibility is not known, determination of combustibility shall be determined by one of the following tests:
(1) A screening test based on the UN Recommendations on the Transport of Dangerous Goods: Model Regulations — Manual of Tests and Criteria, Part III, Subsection 33.2.1, Test N.1, “Test Method for Readily Combustible Solids”
(2) Other equivalent fire exposure test methods
5.4.1.2* For the purposes of determining combustibility, if the dust in the form tested ignites and propagates combustion or ejects sparks from the heated zone after the heat source is removed, the material shall be considered combustible.
5.4.1.3 If the dust is known to be explosible, it shall be permitted to assume that the dust is combustible and the requirements of 5.4.1.1 shall not apply.
5.4.2 Determination of Flash-Fire Hazard. (Reserved)
5.4.3 Determination of Explosibility.
5.4.3.1 Where the explosibility is not known, determination of explosibility of dusts shall be determined according to one of the following tests:
(1) The “Go/No-Go” screening test methodology described in ASTM E1226, Standard Test Method for Explosibility of Dust Clouds
(2) ASTM E1515, Standard Test Method for Minimum Explosible Concentration of Combustible Dusts
(3) An equivalent test methodology
5.4.3.2* When determining explosibility, it shall be permitted to test a sample sieved to less than 200 mesh (75 μm).
5.4.3.3* When determining explosibility, it shall be permitted to test the as-received sample.
5.4.3.4 It shall be permitted to assume a material is explosible, forgoing the requirements of 5.4.3.1.
5.4.3.5* When the representative sample has a characteristic particle size smaller than 0.5 μm, the explosibility screening test method shall account for possible ignitions in the sample injection apparatus.
5.4.4 Quantification of Combustibility and Explosibility Characteristics.
5.4.4.1* Where dusts are determined to be combustible or explosible, additional testing shall be performed, as required, to acquire the data necessary to support the performance-based design method described in Chapter 6; the DHA described in Chapter 7; the risk assessments described in Chapter 8; or specification of the hazard mitigation and prevention described in Chapter 8.
5.4.4.2 The owner/operator shall be permitted to use the worst-case characteristics of the various materials being handled as a basis for design.
5.5 Sampling.
5.5.1 Sampling Plan.
5.5.1.1 A sampling plan shall be developed and documented to provide data as needed to comply with the requirements of this chapter.
5.5.1.2 Representative samples of dusts shall be identified and collected for testing according to the sampling plan.
5.5.1.3 The sampling plan shall include the following:
(1) Identification of locations where fine particulates and dust are present
(2) Identification of representative samples
(3) Collection of representative samples
(4)* Preservation of sample integrity
(5) Communication with the test laboratory regarding sample handling
(6) Documentation of samples taken
(7) Safe sample collection practices
5.5.2* Mixtures. If the dust sample is a mixture, the approximate proportions of each general category of particulate solid shall be determined and documented on the basis of available information and shall be used to assist in determining representative samples.
5.5.3* Representative Samples. Samples collected from each location shall be representative of material used in the process or equipment or found on surfaces at that location.
5.5.4* Sample Collection. Dust samples shall be collected in a safe manner without introducing an ignition source, dispersing dust, or creating or increasing the risk of injury to workers.
5.5.4.1* Samples shall be uniquely identified using identifiers such as lot, origin, composition (pure, mixture), process, age, location, and date collected.
Chapter 7 Dust Hazards Analysis (DHA)
7.1* General Requirements
7.1.1 Responsibility. The owner/operator of a facility where materials that have been determined to be combustible or explosible in accordance with Chapter 5 are present in an enclosure shall be responsible to ensure a DHA is completed in accordance with the requirements of this chapter.
7.1.2* The requirements of Chapter 7 shall apply retroactively in accordance with 7.1.2.1 through 7.1.2.3.
7.1.2.1 For existing processes and facility compartments that are undergoing material modification, the owner/operator shall complete DHAs as part of the project.
7.1.2.2* For existing processes and facility compartments that are not undergoing material modification, the owner/operator shall schedule and complete DHAs of existing processes and facility compartments within a 3-year period from the effective date of the standard. The owner/operator shall demonstrate reasonable progress in each of the 3 years.
7.1.2.3 For the purposes of applying the provisions of 7.1.2, material modification shall include modifications or maintenance and repair activities that exceed 25 percent of the original cost.
7.2 Criteria.
7.2.1* Overview. The DHA shall evaluate the fire, deflagration, and explosion hazards and provide recommendations to manage the hazards in accordance with Section 4.2.
7.2.2* Qualifications. The DHA shall be performed or led by a qualified person.
7.2.3 Documentation. The results of the DHA review shall be documented, including any necessary action items requiring change to the process materials, physical process, process operations, or facilities associated with the process.
7.3 Methodology.
7.3.1 General. The DHA shall include the following:
(1) Identification and evaluation of the process or facility areas where fire, flash fire, and explosion hazards exist
(2) Where such a hazard exists, identification and evaluation of specific fire and deflagration scenarios shall include the following:
(a) Identification of safe operating ranges
(b) * Identification of the safeguards that are in place to manage fire, deflagration, and explosion events
(c) Recommendation of additional safeguards where warranted, including a plan for implementation
7.3.2 Material Evaluation.
7.3.2.1 The DHA shall be based on data obtained in accordance with Chapter 5 for material that is representative of the dust present.
7.3.3 Process Systems.
7.3.3.1* Each part of the process system where combustible dust is present or where combustible particulate solids could cause combustible dust to be present shall be evaluated, and the evaluation shall address the following:
(1) Potential intended and unintended combustible dust transport between parts of the process system
(2) Potential fugitive combustible dust emissions into a building or building compartments
(3) Potential deflagration propagation between parts of the process system
7.3.3.2 Each part of the process that contains a combustible particulate solid and that can potentially include both of the following conditions shall be considered a fire hazard and shall be documented as such:
(1) Oxidizing atmosphere
(2) Credible ignition source
7.3.3.3* Each part of the process that contains a sufficient quantity of combustible dust to propagate a deflagration and that can potentially include all the following conditions shall be considered a dust deflagration hazard and shall be documented as such:
(1) Oxidizing atmosphere
(2) Credible ignition source
(3) Credible suspension mechanism
7.3.4 Building or Building Compartments.
7.3.4.1 Each building or building compartment where combustible dust is present shall be evaluated.
7.3.4.1.1 Where multiple buildings or building compartments present essentially the same hazard, a single evaluation shall be permitted to be conducted as representative of all similar buildings or building compartments.
7.3.4.1.2 The evaluation shall address potential combustible dust migration between buildings or building compartment
7.3.4.1.3 The evaluation shall address potential deflagration propagation between buildings or building compartments.
7.3.4.2* Each building or building compartment that contains a combustible particulate solid and that can potentially include both of the following conditions shall be considered a fire hazard and shall be documented as such:
(1) Oxidizing atmosphere
(2) Credible ignition source
7.3.4.2.1* The evaluation of dust deflagration hazard in a building or building compartment shall include a comparison of actual or intended dust accumulation to the threshold housekeeping dust accumulation that would present a potential for flash-fire exposure to personnel or compartment failure due to explosive overpressure.
7.3.4.2.2 Threshold housekeeping dust accumulation levels and nonroutine dust accumulation levels (e.g., from a process upset) shall be in accordance with relevant industry- or commodity-specific NFPA standards.
7.3.4.3 Each building or building compartment that contains a sufficient quantity of combustible dust to propagate a deflagration and that can potentially include all of the following conditions shall be considered a dust deflagration hazard and shall be documented as such:
(1) Oxidizing atmosphere
(2) Credible ignition source
(3) Credible suspension mechanism
4.2.4* Compliance Options. The objectives in Section 4.2 shall be achieved by either of the following means:
(1) A prescriptive approach in accordance with Chapters 5, 7, 8, and 9 in conjunction with any prescriptive provisions of applicable commodity-specific NFPA standards
(2) A performance-based approach in accordance with Chapter 6
4.2.5 Where a dust fire, deflagration, or explosion hazard exists within a process system, the hazards shall be managed in accordance with this standard.
4.2.6 Where a dust fire, deflagration, or explosion hazard exists within a building or building compartment, the effects of the fire, deflagration, or explosion shall be managed in accordance with this standard.
9.5 Training and Hazard Awareness.
9.5.1* Employees, contractors, temporary workers, and visitors shall be included in a training program according to the potential exposure to combustible dust hazards and the potential risks to which they might be exposed or could cause.
9.5.2* General safety training and hazard awareness training for combustible dusts and solids shall be provided to all affected employees.
9.5.2.1* Job-specific training shall ensure that employees are knowledgeable about fire and explosion hazards of combustible dusts and particulate solids in their work environment.
9.5.2.2 Employees shall be trained before taking responsibility for a task.
9.5.2.3* Where explosion protection systems are installed, training of affected personnel shall include the operations and potential hazards presented by such systems.
9.5.3 Refresher training shall be provided as required by the AHJ and as required by other relevant industry- or commodity-specific NFPA standards.
9.5.4 The training shall be documented.