ARE ROTARY VALVES EXPLOSION PROOF? “HERE COMES THE BOOM”

“You turn me out, you turn me on,  you turned me loose, then you turned me wrong,

You dropped a bomb on me, baby You dropped a bomb on me.” - The Gap Band’s 1982 hit “You Dropped a Bomb on Me”

Explosions can be a scary thing to even contemplate. In the dry bulk material handling world, they are a fact of life that we often have to design around. NFPA 69 is the standard used to regulate explosion suppression or containment. One of the methods that this regulation allows for to discharge material out of a filter or bin, is a rotary valve.

Rotary valves can be used in this service if they meet 1 of 2 criteria: Either they are designed with close tolerances (<0.2 mm) OR they are insured to always have a head of material above the inlet. Most customers choose to go the close tolerances route, as monitoring the depth of material above a valve is harder than keeping track of a teenager with a car on a Saturday night.

At Smoot Company, all of our valves meet the criteria required as long as:
1. They are not supplied with flex tips
2. They are not going into high temperature (> 180˚ F) service
3. The Pmax of the dust is not > 14.9 PSIG

That being said, once the valve is placed into service many customers may not realize that there are additionally 2 requirements placed on to them to keep the valves in compliance:
1. The motor has to be interlocked so that if an explosion starts, the rotary valve is stopped from spinning.
2. While the tolerances are in compliance when they leave our shop, they must be regularly monitored to make sure they STAY in compliance, and clearances don’t widen due to wear.

Nobody wants an explosion to happen on their watch. And to paraphrase former ESPN Sports Center host

Dan Patrick “You can’t stop a (dry bulk material explosion), you can only hope to contain him”. With a properly applied rotary valve, containment just became a whole lot easier, so you won’t be “en feugo.

For more information on Rotary Valves Click Here.

Submitted by: Larry Eagan | Regional Sales Manager