On Tuesday 07 February 2017 18:30:18 Leonardo Marsaglia wrote: > Hello to all! > > I'm in the process of designing and planning a system to rapid > heating/cooling a mold for plastic injection. The project is still in > the board so I think it's a good time to ask help from you guys. > > I'm trying to make the system as simple as possible so I'll tell you > what I have in mind and what are my doubts and concerns. So here it > is: > > A high pressure vessell with resistors is what I'm planning to have as > an accumulator and heating device. (The vessel should have pressure > relief valves and maybe a rupture disc). The idea is to reach 1000 PSI > (to avoid water to start boiling) and 280°C. From what I've been > reading the best pump for this cases is a gear pump because it can > handle better the thermal dilatation of the components. > > My main concern is, at the inlet of the pump the pressure is going to > be 1000 PSI, and I have only worked with pumps at atmospheric pressure > at the inlet side. Is this going to be a problem? The differential > pressure at the output is intended to be 50 or 100 PSI more than at > the inlet just to make the water flow through the mold and return to > the vessel. There are going to be valves to switch between cool and > hot water. > > Also I may need to consider using special materials on the pump > because of the corrosion, or may be some additives in the water, but > my main concern is the rough construction of the system. I'm attaching > a little diagram with my idea just to start and discuse if it's doable > or not. Needless to say I'm going to take every safety measure > possible with this kind of system. > > I would be thankful if you can guide me or tell me if this is too > complicated and dangerous to even give it a try. > > Thanks as always!
Corrosion control for something like that is to maintain the water with a deionizer system. Kill the conductivity, and you have pretty well stopped the corrosion. The main problem I'd see is the water needs to be not more than 150F as it goes thru the deionizer cartridge. Culligan can handle that with a wound fiberglass bottle that I ran as a bypass system on that 1955 GE transmitter. I'd pulled a 1/8" pipe plug out of the top of the pump casting, putting a small needle valve in its place, then ran some plastic ice maker tubing over to the cartridge sitting on a shelf, hooked up by way of some adapters since the cartridge had the usual 3/4 hose bib fittings on it, then a std piece of cheap hose back over to the tank. That totally stopped the electralisis (sp?) driven corrosion. We had 4 places in that plumbing that was grounded on one end of a piece of 1" ID hose about 6 feet long, with 7200 volts at the pipe fitting on the other end of the hose. I had my choice of swaged, galvanized iron hose barbs, or brass ones that while quite a bit shorter, were also much smoother for the water flow. Paid 10x the price for the brass version, but with grocery store distillled water in it, those hose barbs were junk in 6 months. Since it was a 2 man all night job to change them out every 6 months, I instituted the culligan deionizer to keep the water in better shape. I think it was 2 years later I got nervous and changed the hoses and barbs again, but the ones I took out went on the shelf for future re-use as they were not damaged other than some discoloration. When we shut it off on June 30th 2008, the set I'd put in, in about 1998 were still in there, working just fine. I'd stick the probes of a std DVM into the water in the tank, and if it was under 5 megohms, I'd haul the cartridge down to Culligan and get it re-charged. About a $100 bill at the time. I'd guess at about yearly intervals. Bring it back & get the flow running, and in a week, the probes couldn't find the water. That was the general idea. But I don't think the glass tank would have been happy at above 200F water. Now I need to go check on my baby, she wasn't cogent when I was there about 6pm. They didn't work on her till the middle of the afternoon. :( Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
