| | What quality DI water do you need(ie >1 MOHM, 18 MOHM)? | | | | What state are you located? | | | | What type of volume will you use (1 drum per week, month, year)? | | | | Mike | | (800) 218-8128 | | | | We are located in Illinois (Southwest Suburb of Chicago). Our usage will probably be in the 1 drum per month ballpark. We don't need mega-quality (1 MOHM would probably suffice) water, since we're only using it for cleaning wave solder fluxing equipment. | For the 10 litres/day, your best bet is a filter/mixed bed deioniser with, say, 50 - 100 litres of resins. With medium quality tap water, this will last you typically 2-3 months before a cartridge change at 1 �S-cm. Initial capital cost, with a conductivity meter, will be typically in the thousand buck range and cartridge changes a few tens, if you shop around. If you buy the stuff in, with a guarantee on quality and stated packing dates, it will probably cost you 2-3 times more, counted over a 2 year amortisation. If it's cheaper than that, then it is probably not good quality, because the guy who is packing it will probably be doing exactly the same AND you will be paying for the containers. Remember, never store DI water in an opened container for more than a week: it will no longer be DI.
FYI, my company made thousands of litres of ionic conductivity testing solution (50% and 75% purest isopropanol, rest RO + DI water with conductivity < 0.075 �S-cm) and we had to re-polish the water back to spec if it had been kept in a sealed container for just one day. OK, I grant you, this spec is a lot tighter than you need, but it illustrates how unstable DI water is. If you have an open tray of such water, it will stabilise from 0.075 to c. 1 �S-cm (depending on local pollutants) within hours, without agitation, much faster with.
Brian
reply »