Rescuing wet electronics
 

One of our outreach robots was the victim of a flash flood, and collected a significant amount of rainwater (while powered off) before being safely stowed.

Almost all electronics (PDB+fuses, Talon SRs, cRIO, DSC, breaker, relays, solenoids) were exposed to this water. No voltage has been supplied to the robot after its exposure to water.

What's the best way to go about ensuring that electrical components/the robot can be safely used again?

Re: Rescuing wet electronics
 

Rice has been a popular trick to get moisture out of eletronics, put said electronic device in a bag of rice and let it sit over night. Since FRC electronics are easy to take apart though, I would strip everything down wipe it off and then put them in rice.

Also with breakers and such make sure the contacts haven't rusted or you might need to toss them. Same with bearings/etc.

Re: Rescuing wet electronics
 

Do you have access to a large vacuum chamber?

Re: Rescuing wet electronics
 

Sadly no. We barely had access to a tarp.

Re: Rescuing wet electronics
 

A facility full of rice... then put your robot in there

Re: Rescuing wet electronics
 

While this is not a problem for my family and I, we may have to take Mk.32's suggestion and strip down the electronics/dry them individually instead.

Re: Rescuing wet electronics
 

Just put it somewhere where the water can drain and it can dry out. A little bit of air circulating might help dry it faster.

It is common for a lot of electronics to actually be washed in something that looks like a giant dishwasher. Admittedly not all components are suitable for washing but a lot are.

We have a few robots that have been drenched multiple times by intense thunderstorms. We just take our time and let them air dry after dumping out the excess water.

Some of the bearings we didn't have to change out for a couple of years.

Re: Rescuing wet electronics
 

Um, seriously: It is good that it was powered off.

Take everything out and wash it in clean water. Things like speakers and wires are trash (as are breakers), but PC Boards are usually OK since they get washed as part of the production process.

Disassemble the cases of each item, then wash and lightly scrub (use a soft bristle brush like a toothbrush) under water to remove any surface contaminants (like mud). Rinse in clean water, then rinse with 91% isopropyl alcohol and set it to dry. Blow the board with compressed air or a 'duster' if possible to get any trapped liquids from under components.

After it dries - at least overnight! - inspect the circuit carefully. If you don't see any corrosion or other issues, let it dry another few days (you can bake it at about 130 degrees Fahrenheit for 2 hours if there's no plastic), then reassemble it (you cleaned the casing, right?) and power it up.

In about 70% of such cases the device will power up and run fine. Conformally-coated boards like Jaguars and the PDB will have a high success rate.

Unrelated: This also works with phones, but few of us can disassemble the phone for this. Note that phones also have moisture-sensitive labels which turn color to show it was wet, thus voiding the warranty. If you can't disassemble the device, it is often trash, but rinse it thoroughly in distilled water then let it dry for a week or more; ideally sealer in a chamber (like a ziplock bag) with a desiccant (such as silica gel or, in a pinch, white rice).

Good luck, let us know if you did this and how it turns out.

Re: Rescuing wet electronics
 

I have worked in marine research area for years. Several years ago I was involved in a vessel sinking offshore. We had in excess of $200,000 of marine data collection instrumentation on board that went to the bottom. We called in divers and a vessel salvage crew and raised the vessel within 24 hours. When the divers brought up the vessel and gear I quickly opened up all the electronic deck boxes and flushed away the salt water with distilled water then the distilled water with isopropyl alcohol then dried everything as best I could with paper towels and spray cans of air, and a hair dryer. I let everything air dry for a few days. All the equipment still works fine to this day. We lost a few laptops but no data. The laptops were the cheapest thing on board and the data on the hard drives were more valuable. We ripped the hard drives out of the laptops and flushed them the same way. Sent the hard drives to a data recovery service and didn’t lose a single byte of data.

My suggestion is distilled water then isopropyl alcohol then dry as best you can. Spray cans of air to get in all the little crevices.

Re: Rescuing wet electronics
 

Rice works because it works as a hygroscopic substance and absorbs moisture. While this ok, it would be better to get a real commercial hygroscopic substance, desiccant. You know those bags with beads in them that you are not supposed to eat.

Any equipment shipped overseas will have big bags of this stuff, go to a big appliance store or any local supplier of big equipment and see if they will give you the big bags that come packed with the equipment.

You could even bag and tag it with these bags inside. Remember time is your friend when it comes to clearing out the moisture.

Re: Rescuing wet electronics
 

If they are really dirty, you could soak them in Ethyl Alcohol which would clean them with no risk to the boards or plastic. The Ethyl Alcohol would displace any water and evaporate very rapidly with no residue.

Re: Rescuing wet electronics
 

All good advice. As noted by several, be sure to remove contaminants and watch for corrosion, then remove the water and check again.

Another good (but slower) way to draw the water out is to place the (preferably disassembled) components in a working refrigerator. Of course, you would not want any open/unsealed food or drink items with this, as they will add moisture to the air as well.

Re: Rescuing wet electronics
 

Rain water is generally pretty clean. To point you cannot use conductive style probes for level detection. I would dissemble cases that can collect water like roboRios & PDBs. Blow nooks & crannies with dry compressed air (good luck with that) or canned air. If it was submersed in flood water a more thorough cleaner like Don suggests is in order.

As a side note IBM used to immerse their mainframes in water for cooling. I understand immersive cooling technology is coming back although generally with fluids other than water.

Re: Rescuing wet electronics
 

The OP did say "rainwater", but he also said "flash flood", so it's unclear how clean was the water that got into the bot.

Also, is the rainwater in NYC cleaner than LA rainwater?

Re: Rescuing wet electronics
 

Watch the movie "Spare Parts" :)