It’s safe to say that these ruined products won’t make it to the shelf, which is why it’s important that every valve is designed to handle each different combustible dust in order to properly prevent deflagration.
But how do you find out the combustibility of your material?
Watch this video to find out what you need to know about DHAs and NFPA 652—then read our tips listed below.
What is NFPA 652: Standard on the Fundamentals of Combustible Dust?
This is your starting point to evaluate your particulate being handled and the safety in your whole system and facility. It outlines the mandatory requirement for owners and operators in a facility to have a Dust Hazard Analysis.
The Dust Hazard Analysis
DHAs help determine how combustible your particulate dust is and which measures you will need to take to protect your facility and prevent explosions in your systems.
To stay compliant with NFPA 652, plant owners and operators must complete DHAs for existing processes and facilities within three years of the release of the standard, in October 2015.
Here is a list of testing methods you can apply for your DHA:
- Hazard Operability Analysis (HAZOP)
- Checklist analysis
- Failure Mode Effects Analysis (FMEA)
- Layers of Protection Analysis
- United Nations: Transport of Dangerous Goods Manual of Tests & Criteria—Test method for Readily Combustible Solids
- ASTEM E1226: Standard Test Method for Explosibility of Dust Clouds
- ASTM E1515: Standard Test method for Minimum Explosible Concentration of Combustible Dusts
Once your DHA is complete, your dust will be given a KST Value. There are four classes for KST values, as seen in the chart below.
Zero Explosion Value: Rock dust would fall into this category
Class One: One to 200
Class Two: 200 to 300
Class Three: 300 to 400
Reduced Pressure (P-Red) is the maximum pressure developed in a vented enclosure during a vented deflagration.
The P-Red and KST value of your dusts determine the pressure rating required of your rotary valve. It’s important to make sure that your rotary airlock housing, endplates and rotor are the right strength, and are maintained well to handle the P-Red.
Keeping a proper record of when your rotor needs replacing will help keep your valves compliant with NFPA. For easy replacements, drop-in replacement rotors are available when you need them.
More information on NFPA 652 and Deflagration
Check out some more of our resources below:
- Everything you need to know about NFPA 652
- ACS deconstructs deflagration
- What you need to know about isolation devices
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ACS Valves designs, engineers, and manufactures high-quality, high-performance rotary valves for metering, feeding, and airlock in bulk material processing and pneumatic conveying applications.ACS Valves products are sold through a global network of sales engineers and supported by a corporate staff of applications engineers and customer services ...