Q. I am currently working on a streamer/angel-hair problem where I work. What is the proper psi setting for a delivery truck unloading material to a silo? Are there guidelines or proper handling procedures?
—Greg Marshall, Toyota team leader, Jackson Plastics, Nicholasville, Ky.
A. Limit railcar or truck unloading pressures to 6.5 psi maximum. We recommend hanging a sign at the connection point on the silo warning personnel not to exceed 6.5 psi unloading pressure from bulk trucks. Still, angel hair can be created whenever plastic is transferred from one location to another. As the plastic travels through conveying lines, it can “rub” onto the walls of the tubing, building up residue on the walls and eventually creating small streamers, “skins,” or angel hair. This can even happen in the resin production plant before you receive the material. It is a good idea to install an angel-hair trap at the bottom of your silo to prevent streamers from entering your process. You can also use conveying tubes with spiral grooves or “rifling” to greatly reduce or eliminate streamers. High-wear elbows in the bends of tubing reduce streamer build-up in these areas.
Doug Brewster, National Sales Manager
The Conair Group
Cranberry Township, Pa.