Tom: A couple of comments.
1. I have never found a good monitor and control system that didn't bring
more headaches than it was worth. However if you have a fairly steady thru
put of product i.e. square footage being processed in the washer and you
know your dragout in gals/hr you can put in a chemical feed pump.
This would continually dose the wash sump at a given rate (ml/min) or
whatever units and time you want. This is typically tied into the washer
control system so it's only running while product is  being washed. This
will give you a pretty good steady state concentration.

2. Regarding bath turnovers and mask and solids loading. Be careful on your
assumption for wash bath turn over. You do not actually turn the complete
bath over in 12 shifts and create a fresh bath. Example: You have a 1 liter
beaker filled to the top with water that has red dye. You add a second liter
of water without dye to this, mixing into and overflowing out of the
original beaker. After adding the second liter of water to the original is
the water now clear water white? No it is pink. You have diluted the
original but not replaced it. To make it a little more complicated you are
constantly adding more dissolved solids and water soluble mask as you
process additional boards. So you are continually adding contaminates and
removing a percentage thru dragout.


Regards

Michael Barmuta

Staff Engineer

Fluke Corp.

Everett WA

425-446-6076

-----Original Message-----
From: Tom Gervascio [mailto:[log in to unmask]]
Sent: Thursday, November 20, 2003 4:22 AM
To: [log in to unmask]
Subject: [TN] Automatic monitoring systems for in line cleaners


We are considering using an automatic system to monitor and control
additions of a saponifier to our Electrovert H400+ wash. Any recommendations
on systems that other's have used? Any trade-offs on closed loop monitoring
systems using pH versus refractometer? I thought that if you use water
soluble masks that the dissolved materials might influence the dissolved
solids measured with refractometer. However it seems that drag out with
normal operation approaches 7 gal/8 hour shift. with a prewash and wash
capacity of 95 gallons this means that over 12 shifts that the wash should
be turned over but I suspect that all the material may not be turned over
due to dead spots in the construction of the wash (i.e. 2" level in wash
below a U joint that connects the prewash to the wash section). That said is
location of the sensors critical- i.e. place them in these areas where the
wash may be stagnant or items may settle to the bottom of tanks and heaters.

Thanks for the input

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