Founded in 1896, the National Fire Protection Association (NFPA) created its Committee on Safety to Life, which used the lessons learned from the Triangle Shirtwaist fire to develop new guidelines for fire safety. The committee’s work eventually led to fire prevention codes that are in use globally. One of the standards is NFPA 69, the Standard on Explosion Prevention Systems.
What is NFPA 69?
Essentially, NFPA 69 looks at how systems meant to prevent explosions should be designed, installed, operated, maintained, and tested.
According to the NFPA:
“This standard provides requirements for installing systems to prevent and control explosions in enclosures containing flammable concentrations of gases, vapors, mists, dusts, or hybrid mixtures. It is intended for use by design engineers, operating personnel, and AHJs” (authorities having jurisdiction).
In short, NFPA 69 looks at several fire safety issues, which include:
- Active isolation systems that utilize either or both mechanical or chemical solutions for isolating fire
- Controlling concentrations of oxidants that can directly cause or contribute to a fire
- Ensuring combustible material isn’t concentrated to pose a fire hazard
- Passive isolation devices like rotary valves, which keep flames from spreading by reducing oxygen availability or physically preventing their spread
- Promoting spark extinguishing systems that detect and eliminate sources of ignition to prevent fire or dust explosions
- Suppressing and containing explosions should they occur.
The NFPA’s standards have been adopted by many international, federal, state, and local regulatory bodies to protect manufacturing facilities from fires, explosions, and other hazards. According to data compiled by the NFPA and NFIRS (National Fire Incident Reporting System), over 5300 fires occur annually at US processing and manufacturing plants. Yet the costs of these fires go beyond factory infrastructure, which is replaceable and usually insured, to the health and safety of a company’s workforce.
Rotary Airlocks & NFPA 69 Compliance
As noted above, rotary airlocks are passive isolation devices. Yet rotary valves can either hinder or help with fire safety, depending on their design and maintenance. To understand how rotary airlocks work, it’s important first to understand how and why fires and explosions occur in industrial settings.
Manufacturing and processing facilities tend to be more apt to experience structural fires, partly because of the combustible materials often conveyed along production lines. It takes three main things to start a fire: fuel, oxidant, and a source of ignition. Deflagrations are even more complex to deal with than fires. They occur when a heat source ignites material near it, creating a deflagration. These fires move quickly along production lines, consuming ever more material, leading to a domino effect that makes it very difficult to contain.
Deflagration requires the following to be present:
- Fuel, which in many facilities includes combustible dust
- Oxidizer to keep the fire going
- Ignition sources, such as hot material or heat from friction
- Concentrated dust particles confined within an area
Rotary valves play a significant role in keeping these conditions in check. By managing ignition and fuel sources, they limit the oxygen supply to the fire. Acting as isolation devices, they stop flames from spreading along the production line.
To comply with NFPA 69, rotary airlocks must have certain design specifications and be made from certain materials. They also must be regularly maintained to ensure safety, including using the correct replacement parts. For this reason, inspection also plays a big part in NFPA 69 compliance.
Prater Airlocks for Maintaining NFPA 69 Compliance
Prater Industries makes rotary airlocks designed to comply with NFPA 69 standards. Our airlocks have been tested in a third-party testing facility to go beyond merely complying with these guidelines. Prater’s airlocks are certified to comply with NFPA 69 requirements and exceed them. Our airlocks underwent rigorous testing to be certified and can successfully isolate fires and keep them from spreading. With the many years we’ve spent manufacturing and engineering rotary airlocks, Prater has several proven designs available for our customers.
Prater’s rotary airlocks include:
- Abrasion-resistant airlocks that are specially treated to ensure durability when working with abrasive and corrosive products and processes.
- Blow-Thru airlocks are designed specifically for use with pneumatic conveyancing systems.
- Dust Collector Series airlocks made for general use and to work with cyclones, dust collectors, and hoppers.
- Heavy-Duty PAV Series airlocks prove ideal for handling free-flowing, dry powdered material in applications with pressure differentials, such as production lines that utilize pneumatic conveyancing.
- Quick Take-Apart airlocks with rails offer a means for quick disassembly while also protecting the rotor during maintenance.
- Quick Take-Apart airlocks work well for applications where the airlock requires frequent removal or quick cleaning.
Prater understands how pressure, temperature, and airlock construction, play an important part in how rotary airlocks operate. Each of our airlocks is designed for specific applications and can be customized to meet a customer’s unique prerequisites. To determine the size needed for your rotary airlock’s specific application, we also encourage you to try Prater’s airlock calculator tool. For more information on our rotary airlocks and how they help our customers achieve NFPA 69 compliance or any other equipment, we invite you to contact one of Prater’s expert technicians.
