I just posted this information on HokieMojo’s blog
I hope this helps someone planing a dust collection system or air piping.
Plumbing 101 ( I used S&D piping on my dust collection system.)
Below are different types of pipe and their general uses.
Schedule 80 PVC is gray and is mainly used for commercial applications. Also very expensive.
#1- Schedule 40 PVC can be used for pressure or drainage applications and has a wall thickness of about a 1/4 inch. The pipe is white and the color code printed on the side, most of the time is either red or blue. The fittings are different though. The fittings for drainage are called DWV (drainage, waste, vent) and they do not make them in a size less than 1- 1/2” and anything 1-1/4” and below is strictly used for cold water pressure applications only. (This pipe can melt if used on Hot water!!)
#2- What we plumbers in my locality call foam-core can only be used for DWV application. They came out with this product a few years back to save cost in manufacturing, plus it does not conduct noise as much when used on drainage, regular schedule 40 conducts a lot more noise. Foam-core pipe is also more brittle and breaks easier. The (ID) or inside diameter and the (OD) outside diameter of foam-core and schedule 40 are exactly identical. The pipe is also white and the color code on this pipe is usually Black. Uses the same glue and primer as schedule 40.
#3- S&D piping is PVC pipe used strictly for underground utilities such as septic tanks and storm drain connections for down spouts. It has a wall thickness of about 1/8 to 3/16 inch. I do not think this pipe comes in any other sizes larger than 4 inch or 6 inch. The fitting choices for this pipe is limited. However they do make hub adapters enabling you to use schedule 40 fittings. Same glue and primer as schedule 40.
#4- CPVC piping is used for domestic water. Hot or Cold. The pipe is usually beige with a black lettering code on the side and the glue used is orange.
NOTE! (You can not use regular PVC glue on this pipe) this pipe cannot be mixed with PVC. the sizes are slightly different.
#5- schedule 40 Galvanized threaded pipe is for water and air applications. It is not used for gas because the galvanising can flake and cause blockages in the orifice. Note (most building codes do not permit use for water any more)
#6- Schedule 40 black threaded is mainly used for natural gas and petroleum products. NOTE ( Do not use for air lines) The moisture in the air will cause rust on the interior walls and then be transmitted to the equipment being used, such as spray guns, etc., etc.
I hope this helps someone and God bless
P.S. About grounding. I am sure it needs to be grounded with the wire ran on the inside of the piping. If you spiral rap it on the outside? Well, (YOU) won’t get a static charge. However, this will not prevent a fire. I may be wrong, so (PLEASE) check this aspect out before your installation.
-- Gene, a Christian in Virginia