Replies

1. 
   highfigh | Oct 29, 2005 05:42pm | #1

   You can use either of those, but if you use anything that's non-conductive, you need to run a bare wire through the dust, attached to each machine. This is to dissipate static buildup which can cause the dust particles and the air they're suspended in to become explosive. It also keeps you from getting static shocks when the air is dry enough.

   If you look around enough, you should be able to find metal ducting that isn't too much more $ than plastic and you wouldn't need to worry about the wire unless you use a flexible plastic hose to connect from the machine to the ducts.

   "I cut this piece four times and it's still too short."
1. 
   joepez | Oct 29, 2005 05:52pm | #2

   THANKS FOR THE HELP.

   I REMEMBER A TEST BEING CONDUCTED TO SEE HOW MUCH STATIC IT WOULD TAKE TO BLOW UP A PVC PIPE.

   THE FINDING OF THE TEST WAS IT WAS EXTREMELY UNLIKELY THAT A SMALL SHOP WOULD BE ABLE TO GENERATE THAT KIND OF BUILDUP.

   I AM REPLACING ALL THE FLEX HOSE I ORIGINALLY RAN WITH WIRE IN THE HOSE. I DID NOT CARE FOR THE FLEX HOSE SETUP.  TOO MUCH LOSS OF SUCTION AND TO MUCH INSIDE DIAMETER TURBULENCE WITH ALL THE SPRIALS.

   I AM ONLY RUNNING A DELTA 1 1/2 HP DC WITH 1100 CFM.

1. 
   forestgirl | Oct 29, 2005 06:56pm | #3

   I side with you on the likelihood of a dust explosion -- not to worry, IMHO, and it sounds like you've done your homework.  This is one of those discussions that'll go on forever, it seems, and each to their own.

   Bill Pentz is my guru for ducting info, his page on that subject is here and might help you with your decision.  Section 3 is where he discusses the S&D piping.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)Another proud member of the  "I Rocked With ToolDoc Club" .... :>) 

2. 
   highfigh | Oct 29, 2005 09:09pm | #4

   You have to remember that the static discharge won't necessarily occur in the pipe. Ever seen what happens when a grain silo blows up? Same situation on a bigger scale. If for no other reason, ground everything so you don't get zapped by the static. I got nailed big time the first day I used mine without the ground wire.
   "I cut this piece four times and it's still too short."

2. 
   dondownunder | Oct 30, 2005 06:28am | #5

   Probably best to think in terms of what is available for what you want to do. Here the thin walled stormwater pipe doesn't have the range of fittings that sewer pipe has & the elbows are much tighter. It is also available in a variety of diameters such as 4, 6 & 8" but once you get to the larger diameters galvanised steel duct becomes a better buy.

   Don