Homebrew PCBs

Frank wrote:
> 
> 
> That's great work. A spray etcher is on my todo list. I currently
> just agitate in a plastic container with hot ammonium persulphate.
> 
> Where did you get the spray nozzles from? And what pump are you
> using?
> 

The nozzles were from a company with the web site http://www.spray.com 
You should find a sales office somewhere in your country. They are setup 
for worldwide orders and they don't complain if buying just 1 nozzle.
I used 4 fan type nozzles. Let me know if you want part numbers.

I had to choose the right flow rates nozzles to maximize power usage of 
the pumps. This is estimated by looking at flow rate vs pressure graphs 
of both the pump and nozzle. I have the formulas somewhere. Operating 
pressure is about 2.3 bar which is just below pump limits before causing 
heating problems. Current drain is 6.5A at 12.5Volts per pump. The pumps 
are diaphragm type used for caravan water. These give good pressure, and 
cheap. They are made by Shurflo, but needed modifying internally to make 
them acid resistant. Unfortunately I bought them in the belief there 
were no metal-fluid contact, but I later found the hard way they used 
stainless screws to hold the "pistons". I replaced these with plastic 
coated screws and so far have survived over 1 year in cupric chloride. 
According to customer support at Flojet (competitor) their pumps no not 
have any metal-fluid contact so they should be ok in HCl.
Below are links to  their pumps, and it looks like Shurflo have brought 
out replacement models since. I would suspect they too have internal 
stainless steel screws.

http://www.shurflo.com/pages/RV/rv_categories/general_purpose/generalPurposePumps.html

http://www.flojet.com/prodInfoApp/servlet/DisplayProducts?typeId=FRQSP&page=0&catalogId=RV&categoryId=FRMPU&companyId=FLOJET

The exact pumps I used are here:
http://www.shurflo.com/pdf/rv/product_data_sheets/pds-2088-422-144.pdf

Because they are not terribly expensive I bought 2 pumps, and run them 
in parallel for double flow rate.

Adam