Acid Handling

[yoopertool]

I know that many people dont classify electropolishing a "Mass Finishing Technique", but this forum is the closest I can find. Right now our shop has several EP systems located around the shop in various work cells. As of right now we dont have very good (Safe) methods for transporting and pumping our acid to the different stations. I am thinking of making my own portable acid fill cart that I can take between machines that would help with this situation. Does anyone know of a company that already does this? Carting around a 55 gallon barrel of the stuff is not a good situation. Any suggestions would be appreciated. Thanks

[mactec54]

Hi yoopertool

You should not have this process anywere near your machines, it should be in a separate area in the shop away from all controls & electronics as you will find over time a lot of electronics having to be replaced & no company would do this this way

[yoopertool]

We have had small EP systems around our shop for probably around 12 years without any noticable degredation to our other machines. Each system is fully enclosed with small access doors to load parts and have forced venting systems which go out of the building. I am really just looking to find out if there are any existing products used to transport and pump EP acid in a controlled and safe manner. Thanks agian!

[mactec54]

Hi yoopertool

Now that is different than what was in the first post you have fully enclosed & venting this of course will not do any harm to the machines,

Because this is not that common in a machine shop to have acid (EP) in or around work cells I think you will find it hard to find what you are looking for, to have 55 gallons to be moving around easy, May be you could make a cart for a 5 gallon PP container & have that to move around it would be easer than 55 gallons I have seen what you are looking for but not sure which company it was that sell what you want

[yoopertool]

I think that it is going to come down to me making my own custom cart with built on tanks with pumps. Thanks for the input, and if you find the company you saw one at before please let me know. Thanks

[yoopertool]

Ok, it looks like I am going to make a cart to transport / pump the acid. I was wondering if anyone know what plastic would be best suited to handle hot (200 degree max) acid. If I am correct the EP solution (EPS 4000) is part phosphoric acid and part sulfuric acid with a PH around 1. Any info would be appreciated. Thanks

[Cruiser]

When moving any acid around over a period of time, I would not use any plastic that could dry out, crack or in any way get brittle from acid or heat or any outside influence ! It may be a bit exotic, but, I understand that the refineries which produce these acids use an extruded CP Zirconium tubing (CP = commercial purity) These tubing supplies or other suitable should be available from somewhere for your system. It would be a disaster if anything broke or leaked causing a release of acid within the shop or on any personnel. Glass works good but too easily shattered for a portable system. Unless my memory is totally defunctified I am pretty sure Zirc is inert in use with acid. I used to machine billets and liners that were assembled and drawn out for just that purpose, or so I understood at the time. All we did was the machining, then shipped to customer for the rest of the process, so info I got was hearsay !

[harryn]

Hi,

There are commerical acid carts like this, and they were commonly used in the semiconductor industry. It's not quite as common anymore as moving high purity acid into a clean room and around the area is challenging.

As the volume as acid usage grew, many have installed bulk chemical distribution piping. In those, the acid drums are stored in an H1 or H2 area, and the acids are pumped through double contained lines to the stations in the work areas. The acid can be pumped either with diaphram pumps or air pressure. The plumbing is usually teflon tubing inside of PVC pipe (secondary containment)

These can get pretty sophisticated in their function, but a common method is to have a small plc at each work area. The operator pushes a button, the acid is drained, then refilled automatically, with redundant sensors to make sure nothing overflows.

You can also set them up to "top off", or add trickles of chemical for replenishment.

The largest cost is actually the pipe and installation, the rest of the systems used to run about $ 50 - 75 K / chemical.