Watch out for the steam! 2017-02-08 3:44 GMT+01:00 Gene Heskett <[email protected]>:
> 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 > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
