Homebrew PCBs

At 08:04 AM 9/11/2006, lcdpublishing wrote:
>Hi guys,
>
>Went out to etch a board this morning only to find my tank empty -
>luckily I store it inside a bucket so all was well.  The Ferric
>Chloride siphoned out through the air hose inlet which passes through
>a hole in the side of the tank.  Aside from it completely disolving
>the brass fitting which connects to my compressor, nothing else bad
>happened.

If I may make a suggestion: put a tiny air hole in the hose.  Place 
the hole at the highest point in the siphon - where the hose goes 
over the edge of the bucket.

This hole need not be large - something on the order of a #60 drill 
bit is fine.  If the hose is plastic, even consider using a hot 
needle or a really small soldering iron tip.

The purpose of the hole is to stop a vacuum from forming in the 
hose.  That stops accidental siphoning action.

My tank is quite large (10 gallon tank filled with 7 gallons) and the 
air supply is a vacuum motor blower fed through 1" plastic pipe.  I 
used a 1/8" hole where the pipe goes over the top of the tank - I 
have way more air volume that I need and don't notice the air that is 
lost through the hole.

Even though the blower motor is located about 40" below the top of 
the liquid, I've NEVER had etchant get down into the blower.

I had initially considered using a 1-way valve but finding a valve 
that was low cost, low pressure drop, and impervious to the etchant 
seemed impossible at the time.  The air hole simply eliminated the 
need for the valve.

dwayne

-- 
Dwayne Reid   <dwayner@...>
Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
(780) 489-3199 voice          (780) 487-6397 fax

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