Djävulssnickarn skrev:Sen undrar jag osså över vad man kan ha som filter, funkar påslakan?
Djävulssnickarn skrev:I systemet finns 5 fläktar, en 3kw tömningsfläkt som blåser ut spånet i ett silo, 1 11kw fläkt i sågverket med cyklon, 1 5.5 kw fläkt till vedkapen o fliskvarnen med cyklon. Så är det denna stora 18.5 kw fläkten till snickeriet, där finns bland annat bredbandsputs o andra slipmaskiner och cykloner kan inte avskilja detta damm, då luften återvänder från fläktsystemet in i lokalen så måste allt damm avskiljas så att det inte sprutar in damm. Så finns det en fläkt till, en högvakuumfläkt på 4kw till små maskiner å handverktyg i snickeriet, men till denna ska jag försöka hitta filter från ÅSS. I samtliga fall så sitter fläktarna före filtren
There is always someone who will bring up the concerns about duct static potentially causing an explosion when you use PVC pipe. PVC pipe is an excellent insulator that will build up a static charge, particularly in a dry cold climate. Although that charge can shock you, the experts say it is not ample to cause an explosion in hobbyist based systems. Dr. Rod Cole wrote an excellent article in Fine Woodworking that debunked the static myth with PVC pipe. He also posted that article on a woodworking forum and gave me permission to include a link to his article. If you are still concerned, go read his information. Dr. Rod Cole has some excellent additional information on grounding PVC on his site: Dr. Rod Cole on Grounding PVC (Click here).
Explosion or not, getting a good zap while next to a sharp blade or cutter can be plenty dangerous, so if you live in a dry climate and chose to use PVC, you might want to seriously consider protecting yourself. We cannot ground PVC because it is an insulator, so all we can do is provide a way to bleed of static before it builds to unhealthy levels. Most do something which works poorly which is to run a single grounded wire around the outside of your PVC. If done right that wire also attaches to the metal coil spring inside your flex hose then you ground that wire both at your machine and your blower. However in dry climates, static can be a real pain around tools and doing a better job of grounding your dust collection piping is worth doing. As I said before most grounding approaches do not work well at all and most attempts to put metal inside our ducts leads to plugged pipes. Here is a workable solution shared by one of the many contributors to this site. Thanks for sharing Brent!
Brent Dugan was the Maintenance Supervisor/Plant Engineer for a large 'Meltblown' polypropylene manufacturer (oil sorbents) for 9 years. He shared his way to eliminate those nasty static shocks, "Our product was plastic and our conveying systems both air and mechanical were plastic. Polypropylene fibers traveling through 3" or 4" PVC piping creates massive amounts of static electricity. Our problem was so severe that we had sparks jumping 1 1/4" from our piping that would leave burn marks on your skin. Our employees dreaded working with the equipment. We tried all of the available methods you proposed and more; e.g., wire inside, wire outside, wrapped wire outside, etc. We spent quite a bit of my company's money to try and solve the problem with consultants and experts all to no avail.
I finally came up with a solution. It was so simple and inexpensive that you will not believe it. As you stated, static means electrons building on the surface of an object. Well, I solved the problem by sticking 2" wide aluminum foil tape to the outside and inside of the PVC piping and then grounding that tape. It is easy to just stick the tape on the outside of the pipe. Unfortunately that was not enough and I also had to put a strip of tape on the inside of the duct.
Putting the tape on the inside was an interesting challenge. I wanted my tape inside and tape outside to end up right next to each other with just the PVC in between so I could use a screw and nut to ground the two layers together. I was only able to make the aluminum tape with a backing like double-sided tape work on the inside. To do so I started by sticking the aluminum tape to the bottom edge of the PVC pipe. Slightly peel the backing and adhere the aluminum tape to the end of a piece of 1/2" EMT, conduit pipe, or other long rod. Feed the aluminum tape through the pipe as you unroll it from the roll. When you have the tape through the PVC, stick the aluminum tape to the end of the PVC pipe. Now 'tape' the backing to the rod then stretch the aluminum tape tightly angling it towards the top of the PVC piping (12 o'clock position). This keeps it from sticking prematurely. Now gently pull the rod out of the PVC that also removes the 'backing strip' off as you go. Keeping the aluminum tape stretched tightly lower it to the bottom side of the PVC pipe. To smooth it onto the inside I slipped in a longer piece of PVC and simply rolled that pipe inside to "iron" the aluminum tape down.
Having the tape back to back made grounding easy. I drilled a hole near each pipe end through both layers of foil, inserted a 1/4-20 screw from the inside of the pipe, put on a nut to make a good circuit, then connected each section using 14 gauge wire. I connected each end with alligator clips to another strip of the aluminum tape adhered to the concrete floor. That totally eliminated the massive static electrical discharges and earned me a bonus!"
Some have had problems with this technique. Here is what I did and it worked well to help me install my aluminum duct tape inside my duct. I put my pipe on my workbench oriented with where I want the tape on top. I then attach the tape end sticky side up to a long 2x2 and feed that board through the pipe while unwinding the tape. When it is all the way through stick the tape to the inside top of the pipe using a tennis ball to smooth it down as far as I can reach. From the other end pull the tape fairly tight without tearing. Now take a tight ball of rags and push it through the pipe from that well secured end. This will get the tape stuck. To smooth the tape and stick it well, rotate the pipe down then using a tennis ball on the end of the 2x2 smooth and press the tape down well.
Användare som besöker denna kategori: Inga registrerade användare och 2 gäster