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Re: Farewell and coolant-related machine shop question


Congratulations and good luck in your new position.  It sounds  important . I
hope it is a  promotion.  I will miss your input on P2 tech.

I do not think the lead is coming from the coolant.  The source is likely the
brass.  As I recall, acidic ground water in New England is fairly common.  It
could be that this is the case and the acidic conditions in the rinses is
leaching out lead.  The longer the dwell time, the more lead in solution.   A
pH adjustment would probably help.   Caustic is effective but hazardous, soda
ash is safer and cheap, and TEA may be more compatible with the coolant but it
is expensive.   I think some public water works use lime to prevent leaching in
older lead and copper pipes.    In this case though, calcium hardness from the
lime would likely cause more problems than it solves.   The coolant  probably
has a pH of 9-10, but if mixed with acidic water the use pH could drop to the
acid side and cause leaching in the sawing operation. This could be a source to
check, particularly if it is recirculating and cycles of concentration cause the
lead concentration in the coolant to "cycle " up.

Again, good luck and best wishes.