On Wednesday 08 February 2017 21:22:12 Leonardo Marsaglia wrote: > Thanks to all four your answers! > > I'll try to answer to all of you in one response just to make it more > readable. > > *Andy*: I was reading about PW reactors when I started to plan this > kind of system but I really couldn't find too much information about > it other than general aspects. I was trying to contact EATON to get > information about their Vickers pumps for this application, but no > luck so far. > > *Gene*: I was thinking about using inox tubing to avoid corrosion and > for the ducts on the mold I was thinking about inserting some piping > inside them to make them more corrosion proof. The other thing was to > use some sort of additive in the water but I really don't know it > there's such a product. Same thing goes for the pump wich is going to > handle the high temperature of the fluid.
If there is any electrical potential between the parts, the additives will fail miserably because they will very quickly increase the waters conductivity, leading to electralysis damages quickly. In UHF transmitters where the power levels demand liquid cooling, only one additive is allowed to the deionized water, technical grade ethylene glycol. Pure stuff, no anti-corrosion additives allowed. Same grade they make electrolytic capacitors with. Maximum without taking the building construction into the figures to keep it from freezing, is 30% glycol. because its heat moving ability by the gallon going by is reduced, which can lead to local hot spots, and its slightly more viscous than pure water so the pumps work harder but move less gallons a minute. Eventually something has to give & the last thing you want to happen is a hot spot, melting a hole in a $120,000 (1973 price) klystron. Story time: Coming up on the winter of 1973 when opec created some huge petroleum shortages, I am the transmitter supervisor at KXNE-TV, one of Nebraska ETV's UHF satellite transmitters for Nebraska ETV's statewide network. Getting on into the fall, and the usual place I had been buying a barrel of tech grade ethylene glocol had not been able to locate me a barrel of it, so I got on the horn, scouting the major oil companies for a barrel of it. 3, 4 days later Mobil found me one, sitting on the dock scheduled to be shipped to CD-E about 2 weeks later. I grabbed it, paying about a $3 a gallon premium for it, delivered the next day to our site about 130 miles NW of the Mobil dock in Omaha NE. That was the last barrel in captivity. So now you know what caused that huge shortage of electrolytic capacitors that winter and much of the next summer. > *Nicklas*: That's the main concern about something like this, other > than the investmen since this is a new field for me! > > *Chris*: I really was doubtful about that aspect since I read in some > place that pressurised water reactors have an "air cushion" in the > pressurizer to compensate for sudden increases in water pressure. But > I guess I can't have that problem since I'm planning to heat the fluid > using resistors. > > *Jim, Todd and Gregg*: I was a little bit reluctant about using some > sort of oil because I thought that the heat tansfer ratio of the water > is a lot better than any oil. It is. > But given the benefits in safety and > simplicity of the system using those DOW oils I think I'm going to > contact them to have some more information. I've been reading the > datasheets and they should work pretty well for my application. In > fact, I wouldn't matter to increase the heating and cooling time by 2 > minutes in favour of more safety and simplicity. The maing thing is I > would like that both circuits (cooling and heating) use the same fluid > so I can use the same conducts in the mold. Don't forget that many of those DOW products are some of the purest PCB's on the planet, and to render them safe for the environment takes feeding them and everything they come in contact with, into a 6800F or higher fire. Very unpleasant stuff to deal with, and costly to boot. Been there, done that, even forgot it was there for 15 years hoping it would go away. It didn't. A 500 lb piece of gear, and the dirt it was sitting on cost us almost $30,000 to load it on a Westinghouse truck (they run a disposal service that has a paper trail all the way to the EPA approved furnace that legally disposes of it and gives you a copy to prove it) and wave goodby to it. But we had to get rid of it as the stink is un-mistakable, you know what it is instantly. Bringing that financial liability to your company would be considered Very Bad Form. > I hope I've been clear with this response method, and I know it's not > the usual way here in the list but I didn't want to let anyone out! > > Thanks as always for your help! > > 2017-02-08 22:53 GMT-03:00 Gregg Eshelman <[email protected]>: > > A liquid system has a safety advantage over a system filled with a > > gas, or a liquid that will easily flash to vapor if there's a leak. > > A hot liquid that stays liquid when pressure is let off will only > > spurt through a leak for a short time as the pressure drops. It may > > spray into a mist but it won't (as easily) fill a large volume with > > scalding hot material. (If it's flammable when sprayed into a mist > > in air and there's an ignition source, then you have a bigger > > problem.) > > > > Pressurized hot water will flash to steam (dry steam if it's hot > > enough) and will keep going until the whole system is emptied, and > > the burning hot steam will fill the whole room. > > That's why pressure systems for air or other gasses or hot water get > > hydro tested at low temperatures, to pressures higher than they'll > > experience under normal operation. If something breaks, it spurts > > for a short time. If it's a large break, it spews a lot of water but > > it's over quickly. Pump it up to failure with a gas or heated water > > and it explodes with shrapnel and possible injuries and deaths. > > > > > > > > From: andy pugh <[email protected]> > > To: Enhanced Machine Controller (EMC) > > <[email protected]> Sent: Wednesday, February 8, 2017 > > 1:31 PM > > Subject: Re: [Emc-users] OT: Need some guidance on high > > temp/pressure water circuit > > > > On 8 February 2017 at 19:45, Jim Craig <[email protected]> > > > > wrote: > > > Dowtherm is used in thermal solar power plants. An environmental disaster of epic, bankrupting proportions in the event of a leak of that magnitude. And even the best silicon rubber gasket materiel will swell and degrade to a leak in 2 or 3 years, I've had to deal with that too. > > That sounds a lot less trouble than my molten salt idea. Those are > > super-stable at high temp (and relatively inexpensive) but if > > allowed to freeze would be very troublesome. > > > > > > ------------------------------------------------------------ > > ------------------ > > 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 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
