Dear Lab Guy,

I am trying to set up a recirculating system for an acid bath for etching zinc plates for a traditional printmaking process.

We are using approximately 4.5 gallons of water and 0.5 gallons of concentrated nitric acid, so it seemed like your hand pump H32787-0000 and 5-gallon carboy F10795-0000 might be a good starting point.

Approximately what volume is delivered per stroke at a low head like a foot or two? Alternatively, how many strokes to empty?

Also, would it be acceptable to leave the pump in the acid indefinitely?

Thank you for your assistance.

Walt P.

Hi Walt,

You have made excellent choices, both for the hand pump and the carboy!  Both are made from polyethylene which is the perfect material for handling your nitric acid solution.

For volume calculation, the inner 19-inch tube has a capacity of about 3.5 ounces, or about 100ml.  While this may seem like a small amount, the stroke bore and length are not that great so moving through the cycle should be pretty quick.  Working off of these numbers there would be approximately 36 strokes per gallon.

Finally, leaving the pump in the acid for long periods of time is definitely not recommended. You won’t need to take it out every day or every time you use it, but if it is going to sit in the acid for a longer period of time I’d play it on the safe side and remove it at least once a week and rinse it out with distilled water.

Thanks for writing to Lab Guy, and please feel free to write back if I can help in any other way.

Lab Guy