Is Your Plant At Risk?


When a rotary valve needs repair or maintenance, resulting issues can create a fire risk.

Leaking material, for instance, is a source of combustible dust. Strange noises can indicate

product buildup or increased rotor clearance — a vital sign of a noncompliant valve.

Worn-out or damaged parts can increase the risk of fires, deflagrations, or explosions in a

plant. Keep a close eye on the following valve parts and equipment:

Rotor Vanes: Rotors should have a minimum of eight vanes. To keep flames contained

within the rotor pockets, at least two vanes must stay in contact with the housing at all times.

That means a six-vane rotor won’t do. The vanes must be at least 3 mm thick.


Rotor Tips: Rubber or plastic rotor vanes can’t withstand the heat of a deflagration, so make

sure your rotor is equipped with steel vanes.

(ie. Rubber Tipped Dust Collectors ARE NOT NFPA Compliant)


Shaft Seals: Worn-down shaft seals often cause leaks, which increase the risk of fire as a

source of combustible dust. Replace shaft seals and packing regularly to prevent the issue.


Dust Collector Filters: To prevent clogs and minimize issues with your dust collectors,

including the buildup of combustible dust, keep extra filter bags or cartridges handy.


Long Radius Elbows: Conveying long radius elbows degrade faster than most other parts, and wear can lead to a drop of pressure and leaking material. It’s useful to keep extra elbows in stock to fix the problem.


Rotor-To-Housing Tolerance: Proper clearances are imperative in an NFPA-compliant valve. You must regularly check your valve’s rotor-to-housing clearances, or tolerances, to make sure they stay at 0.0079in. or below. If they get any larger than that, it’s time to replace the valve.

Staying Safe: Precautions For Your Plant

Aside from regular repair and maintenance, you can take several precautions to ensure your rotary valves and conveying system comply with NFPA regulations.

On the valve side, the right outboard bearings will reduce material buildup (a fuel source) and prevent friction (a source of ignition). Specify metal bearings with temperature switches to detect excessive heat. The proper shaft seal assemblies should reduce heat and static electricity.​

It’s worth stocking up on the valve parts mentioned above to ensure you can quickly replace them when the time comes.

If you need an entirely new rotary valve, you should be looking at options that are NFPA-compliant as a standard. 

NFPA 652 requires all facilities that process combustible dust to perform a Dust Hazard Analysis (DHA). Based on the plant and the material being conveyed, the DHA assesses the risks for fires and explosions in a plant, defines prevention methods, and provides training recommendations to keep staff safe from workplace hazards.

Always transport heat-sensitive bulk materials under appropriate temperature, humidity, and conveying gas conditions. Besides that, proper ventilation and regular plant housekeeping are critical. Make sure to stay on top of your preventative maintenance schedule and keep historical logs of everything you do.

Rotary valves help or hinder your fire safety efforts, depending on how they’re made and maintained. It’s essential to understand how fires and deflagrations start in a manufacturing facility.

Manufacturing and processing properties tend to be more prone to structural fires, and conveying systems are rife with combustible materials. Fires start when fuel, an oxidizer, and an ignition source come into contact with each other. Deflagrations are more complicated — and more dangerous.

When a heat source moves over and ignites cold materials, it creates a form of combustion called deflagration. This is a fast-moving fire that can spread across manufacturing lines and consume more material as it progresses, creating a chain reaction that is difficult to contain.​

5 Key Conditions that start a plant deflagration:

     1. Fuel, which comes in the form of combustible dust

     2. An oxidizer, which often means too much oxygen in your system
     3. An ignition source, such as friction or overheated material
     4. Dust particles concentrated in one area
     5. Dust particles confined to a small space

The latter two may take the form of dust clouds in the air or on your machinery.

Rotary valves play a big part in controlling these conditions. They manage fuel and ignition sources and limit the amount of oxygen feeding the flames. In other words, when a fire breaks out, valves act as isolation devices to stop the spread of fire along your conveying line. That said, an NFPA-compliant rotary valve has specific design and construction elements. It also needs regular maintenance and repair to keep it operating safely. To stay compliant, make sure your valve is outfitted with the right parts and watch for signs that your system needs attention.

If you have any questions or concerns with your valves and NFPA compliance give us a CALL or TEXT at (815) 564-1729 or send us a message.

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The NFPA broadcasts their guidelines in book or .pdf format for purchase. These are really wordy with a ton of peoples names that are useless to you and full of legal jargon. Worse yet you have to pay for it.


We have provided a FREE guideline of ALL of the DIRECT measures to make sure you're airlocks are operating with-in the NFPAs Code.


How do I know if my valves are NFPA Compliant?

If you find that you are not in compliance not to worry.


We have the knowledge & expertise to reconstruct your existing airlocks to comply with NFPA-69 guidelines or fabricate a completely new custom airlock for your system that fits within those guidelines.


What If I'm Not In Compliance?

Absolutely Not! Rotary Airlock can, and has, engineered and reconstructed ALL makes & models of airlocks to be NFPA compliant across all industries.


So you'll get YOUR airlock, the way YOU deserve without gouging your budget.


Do I Really Have To Buy Whole New Airlocks?

Last year in the US alone large-loss fires (those with over $10 Million in losses) resulted in 52 deaths, 233 injuries, and an estimated $12.5 billion in direct property losses.


Don't let the loss of those dollar signs and, more importantly, the loss of those human lives land at your feet.


Why Do I Need To Be NFPA Compliant?