NFPA 652 and Bulk Solids Conveyors for Combustible Dust

The presence of combustible dust is a recognized hazard in many facilities. While most are aware of the dangers and take steps to manage them, publication of the National Fire Protection Association (NFPA) 652 standard in the USA has now brought combustible dust under regulatory control. The NFPA is also in the process of combining all combustible dust standards into one consolidated standard (NFPA 660 current planned name) in the near future. Here’s what you need to know.

WHAT IS THE NFPA COMBUSTIBLE DUST STANDARD?

In October 2015, NFPA published the 652 document: Standard on the Fundamentals of Combustible Dust (2019 is the current edition). In doing so, the NFPA sought to address the lack of appreciation and understanding of combustible dust hazards in industry. The NFPA 652 standard introduced a new term, Dust Hazard Analysis (DHA). DHA is aimed at facilities whose processes generate combustible dusts collected by simple dust collectors.

HOW DOES NFPA 652 DIFFER FROM PROCESS HAZARD ANALYSIS?

Within industries whose processes generate combustible dust — such as refining and chemical manufacturing — it’s common to conduct a Process Hazard Analysis (PHA) to analyze and manage the risk. The NFPA 652 standard provides a detailed guide for conducting a hazard analysis on a dust collection system in its appendix. The standard also contains retroactive requirements for implementing a DHA. Within the USA, existing systems were required to perform a DHA by September 7, 2020.

HOW DOES NFPA 652 DIFFER FROM OSHA REGULATIONS?

The term “Dust Hazard Analysis” in NFPA 652 can be distinguished from the more complex PHA, which is required by the OSHA Process Safety Management (PSM) program for the chemical process industry. NFPA 652 does not supplant existing OSHA regulations. The purpose of NFPA 652 is to provide personnel with a single source of information on the fundamentals of safely handling combustible dust and powders in an industrial setting.

HOW CAN COMPANIES USE BULK SOLIDS CONVEYORS TO HELP MANAGE THE RISK OF COMBUSTIBLE DUST?

OSHA regulations contain valuable guidance on controlling the presence of fuel (dust) which could lead to a combustible incident. OSHA guidance centers on controlling three factors:

1. Capturing dust before it escapes into a work area. This involves the use of approved and properly designed and installed dust collection systems.
2. Containing dust within equipment and systems that are built and operated to safely handle combustible dust.
3. Thoroughly cleaning work areas, surfaces and spaces using safe housekeeping methods to remove any combustible dust that cannot be captured or contained.

WHAT ARE THE EQUIPMENT OPTIONS FOR BULK SOLIDS CONVEYORS FOR COMBUSTIBLE DUST?

Handling combustible dust is a critical service application. Bulk solids conveyors for combustible dust are especially designed to allow the dust to be capture or contained, preventing its release into the surrounding space.

At UniTrak, our equipment lineup includes the following bulk solids conveyors for combustible dust:

• TipTrak™ Monocoque bucket elevators. TipTrak™ Monocoque units are explosion-resistant and especially designed to service critical service applications involving combustible dust. TipTrak™ Monocoque units are fully sealed with gasketing to ensure zero fugitive emissions of combustible dust from inside the elevator. As with the PEC model described below, direct connection to a facility’s dust collection system is supported.
• TipTrak™ PEC bucket elevators. These fully enclosed elevators support direct connection to a plant’s dust collection system, allowing dust generated in conveying to be captured. The fully enclosed design helps to contain any uncaptured dust within the elevator.
• Powderflight™ aeromechanical conveyors. Aeromechanical conveyors work on the principle of a fluidized airstream. Because no additional air is required to convey material through the conveyor, there is no excess air at the conveyor outlet to filter for dust. However, careful consideration must be given to controlling dust that may arise from discharged material. In these applications, UniTrak can provide the appropriate solution to ensure that any combustible dust generated is safely controlled.

The presence of combustible dust should never be taken lightly. Current OSHA regulations and the NFPA 652 standard make it more important than ever for companies to ensure that they are actively managing the risks involved with critical service applications containing combustible dust. If you’re looking for proven conveying solutions for critical service applications involving combustible dust, UniTrak is your preferred equipment partner. To find out more about our bulk solids conveyors, contact our sales team directly.