What does a safe valve look like?

Posted by Megan Thompson on Sep 16, 2015
Picture of fire extinguisher

How to keep your plant at low risk for fires

We’ve talked a lot about dealing with unavoidable air leakage recently, but we haven’t discussed the safety factor, which is really the number-one reason to get in front of the air leakage issue.

Without proper ventilation in a pressure conveying system, air will travel back up into the hopper, where it can release material dust into your workplace atmosphere.

On its own, the dust from tiny particles of flour, sugar or metal is harmless. When too many of these particles float up into the air, or land on the surfaces of your plant, however, it can to major problems, such as explosion hazards and fires.

Between 2006-2010, there were 42,800 fires in or at industrial or manufacturing properties in the United States—this amounted to $951 million in property damage, along with 22 lives lost, and 300 workplace injuries, according to the National Fire Protection Association (NFPA).

Tiny particles of dust that make their way through improperly vented systems? Twelve per cent of those fires—5,136 of them—were caused by dust, fiber, or lint catching fire or combusting in these facilities.

As we all know, prevention is the best way to manage risk, so we’ve compiled a safety checklist for specifying and maintaining the safest rotary valves.

  • Keep rotor-to-housing and rotor-to-endplate clearances tight
    • .004” – .006” is a good range
  • Specify outboard bearings and a shaft seal assembly that eliminates bearing failure and frictional heat
  • Ensure at least two vanes are in contact with each side of the valve housing at all times
    • We suggest an 8-vane rotor
  • Specify rotor blade standard thickness is 3/8”
  • Run valves at low tip speed to prevent possible ignition source
  • Avoid rubber rotor tips, use adjustable/replaceable steel rotor tips instead
  • Perform required preventative maintenance, especially to ensure tight clearances
  • Ensure your airlock is properly vented
  • Specify NFPA compliant valves (68, 69, 8503)
  • Keep good housekeeping practices

On top of choosing the safest equipment options in preventing fire hazards in your plant, make sure everyone knows all plant emergency escape procedures and have the ability to account for all of your employees.

Categories: NFPA