Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Scott Davies

#16080

DI Filration And Bacteria | 24 April, 1998

I inherited a DI system that's um...not in good shape. I would be forever indebted to anyone who could help me with several problems related to this. Flow rate 3.5-5GPM Incoming pressure:50PSI Application: deionized water provided to Electrovert H-400 wash machine. Question No.1: Electrovert says that I should have 25-30 PSI going into wash machine. What happens if I don't? What if I can only deliver 20PSI? Question No.2: My water heater is *after* the postfilter, and get this, it's not even stainless. The DI water is actually killing the heater. Does anyone know where I can get a stainless heater? I probably have <$11K for this. Question No.3: Has anyone ever dealt with Culligan in upstate NY? What is the general opinion of their service? Question No.4: Culligan keeps talking about how batch regens of the filter tanks is a bad idea-how bad is it? Question No.5: How much should I worry about bacteria deposition on my PCBs? Bacteria is carbon based so I wonder if we're not headed for trouble with the ever- decreasing pitch of SMT devices.

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Mike Konrad, Aqueous Technologies

#16084

Re: DI Filration And Bacteria | 24 April, 1998

We have purchased several DI water heaters from Coates Water Heaters. (253) 872-7256. They have worked well... A little too much $$$ however. Mike Konrad

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Mikec

#16081

Re: DI Filration And Bacteria | 24 April, 1998

| I inherited a DI system that's um...not in good shape. | I would be forever indebted to anyone who could help me | with several problems related to this. | Flow rate 3.5-5GPM | Incoming pressure:50PSI | Application: deionized water provided to Electrovert | H-400 wash machine. | Question No.1: Electrovert says that I should have 25-30 | PSI going into wash machine. What happens if I don't? | What if I can only deliver 20PSI? Our wash (H400) runs between 20-30 PSI in the final DI rinse.( It seems to fluctuate when someone flushes a toilet). If you have a Ionic cleanliness tester (Omega) test the boards and see what kind of results you are getting, consider lowering the pressure to 15 psi and also test the boards (just to giver yourself a buffer). Also consider, as the nozzles get plugged (although usually not a problem in the DI rinse) the pressure will rise, but the GPM will fall, so pressure alone is not a good indicator( I would install flow meters inline to monitor the GPM). If pressure is still a problem try plugging some of the rear (away from the door) nozzles but only if you are running smaller boards. Keep in mind these machines run in a cascade effect to replenish and purge the wash tanks, therefor less GMP out of the DI rinse will result in a slower purge cycle of your wash tanks. | Question No.2: My water heater is *after* the postfilter, | and get this, it's not even stainless. The DI water is | actually killing the heater. Does anyone know where I | can get a stainless heater? I probably have <$11K for | this. Some things to consider here, Yes the SS heaters are expensive but the power to run those babies is a lot more expensive. You should do some calculations and decide which will be best, if running OPEN loop (dumping all that nice warm expensive water down the drain) or running a closed loop system. Based on my location and considering the cost of the water, the temp rise I needed ( Cost of the power to reach the required temp ), and the cost of the DI beds, it was cheaper to run an open loop system with a heat exchanger to preheat the incoming DI water pre SS heater. The biggest cost factor was going to be the DI beds, running a closed loop system would have required changing the beds out every 2 weeks (not to mention the cost of SS DI tanks (Required for the 150 f temp we required)).. Any way having said all that the best source for SS heater was from the Guligan Man (utilizing a heat exchanger we purchased a 20 gallon SS cost was about 5K) | Question No.3: Has anyone ever dealt with Culligan in | upstate NY? What is the general opinion of their service? I Don�t Know about upstate NY but generally I have been satisfied with Culligan. | Question No.4: Culligan keeps talking about how batch | regens of the filter tanks is a bad idea-how bad is it? I am not sure what you mean by Batch regens, but if you are considering sending your Beds out for regen, its not worth it, the life of regenerated beds is about half of new and if you are changing out your own beds that stuff really stinks..

| Question No.5: How much should I worry about bacteria | deposition on my PCBs? Bacteria is carbon based so I | wonder if we're not headed for trouble with the ever- | decreasing pitch of SMT devices. Beats me

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Scott Davies

#16082

Re: DI Filration And Bacteria | 27 April, 1998

We dump our water. We only run the wash machine a total of three hours a day so there's not a ton of waste there.

Our cation, annion, and mixed-bed tanks are leased. Consequently, they must be sent back for what the vendors call "regeneration," where the resin beads are replaced or treated in some way? Culligan says that the tanks are just regenerated (by the other guy)all at once and that we could pick up tanks from a company that has just let theirs sit around and grow all kinds of junk inside. Should I worry about something like this? We run at 120*F to 140*F. How did you decide on 150*F? Another stupid question: why would SS heaters use more power than others? I think you suggested this. My Culligan connection said he couldn't find a SS heater to save his life. Not very helpful. How come your salesman knows where to find them? I guess I should not have deleted the text. My responses are all over the place and not in order. Sorry. Anyways, thanks for the response, Mike!!

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Mike Cox

#16083

Re: DI Filration And Bacteria | 27 April, 1998

| We dump our water. We only run the wash machine a | total of three hours a day so there's not a ton | of waste there. | | Our cation, annion, and mixed-bed tanks are leased. | Consequently, they must be sent back for what the | vendors call "regeneration," where the resin beads | are replaced or treated in some way? Culligan says | that the tanks are just regenerated (by the other | guy)all at once and that we could pick up tanks | from a company that has just let theirs sit around | and grow all kinds of junk inside. Should I worry | about something like this? I am not sure about what could grow in the tanks, but I have had no problems with tanks hanging around for a couple of months | We run at 120*F to 140*F. How did you decide on 150*F? We probably could to, but most manufacturers recommend 150, We might do some testing to see if we can lower the temp. But it goes back to thats the way I have allways run, and I don't have a whole lot of time to investigate a different setup. | Another stupid question: why would SS heaters use | more power than others? I think you suggested this. If I did, I did not intend to, A KVA is a KVA, but to run a closed loop at 150 the DI tanks need to be Metal rather than the Fiberglass tanks | My Culligan connection said he couldn't find a SS | heater to save his life. Not very helpful. How | come your salesman knows where to find them? I was working with Culligan in Denver, try calling them they will be able to help. I don't work there anymore and of trashed all of the info on my SS tanks | I guess I should not have deleted the text. My | responses are all over the place and not in order. | Sorry. Anyways, thanks for the response, Mike!!

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