Agree with Graham. There are SS and SS ;-) a bit of Ti in the SS, such as
416 would do you a lot of good. On the otherhand, if you use "not so pure"
DI, you actually has less concern about the corrosion of SS ...
jk
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]]On Behalf Of Graham Naisbitt
>Sent: Thursday, July 11, 2002 7:40 AM
>To: [log in to unmask]
>Subject: Re: [TN] Water soluble batch washers.../deionised water
>
>
>On 7/11/02 12:41 AM, "[log in to unmask]" <[log in to unmask]>
>wrote:
>
>> DI Water itself is not corrosive, but it is aggressive, if you get the
>> difference. Having been stripped of all it's ionic content, it's "hungry"
>> to replace those ions, and will draw them from wherever it can.
>That's what
>> makes it so effective at removing ionic contamination from
>boards. However,
>> it doesn't discriminate about where it draws ions from, and
>draws them just
>> as readily from seals and gaskets if it can. Domestic appliance seals are
>> not resistant to this sort of attack, and the loss of ionic content from
>> their composition degrades them to the point where they fall
>apart and dump
>> more dirt back onto boards than is ever removed. The machines
>then leak and
>> eventually become useless for anything.
>>
>> Peter
>>
>>
>> Rudy Sedlak <[log in to unmask]> 10/07/2002 09:08 PM
>> Sent by: TechNet <[log in to unmask]>
>>
>> Please respond to "TechNet E-Mail Forum."; Please respond to RSedlak
>>
>> To: [log in to unmask]
>> cc: (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group)
>> Subject: Re: [TN] Water soluble batch
>washers.../deionized water
>>
>>
>>
>>
>>
>>
>>
>>
>> The "hazards" of deionized water are somewhat blown out of proportion.
>>
>> Deionized water is not really that corrosive, only marginally
>more than tap
>> water...
>> HOWEVER, deionized water lacks the buffering capacity of tap water. (All
>> that water hardness serves to buffer the pH nicely) So, if the "stuff"
>> you are rinsing is corrosive inherently, the deionized water also becomes
>> corrosive, especially to metals.
>>
>> However, most of the aqueous cleaners are pretty mild and
>non-corrosive, so
>> rinsing them with deionized water should be safe, even for the
>common home
>> dishwasher.
>>
>> This is assuming that the ratio of (acidic/corrosive) flux on
>the parts in
>> the washer to the amount of alkaline cleaner being used is not
>so bad that
>> the wash water becomes acidic...then you have BIG problem.
>>
>> The answer is to clean just a few boards, OR use a lot of cleaner to keep
>> the pH above 9, and preferably higher than that...
>>
>> Rudy Sedlak
>> RD Chemical Company
>>
>>
>>
>> [This e-mail is confidential and may also be privileged. If you
>are not the
>> intended recipient, please delete it and notify us immediately;
>you should
>> not copy or use it for any purpose, nor disclose its contents to
>any other
>> person. Thank you.]
>>
>>
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Techies,
As Peter said, De-ionised water is aggressive. It will leach carbon from
welds and over time, degrades stainless steel for the same reason - as was
discovered by the Nuclear Power industry when they found reactor vessels
breaking down.....but that would be somewhat more of a problem than a
scrapped dishwasher!
--
Regards, Graham Naisbitt
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