Re: Ocean-side location corrosion precautions


Christopher Erickson
 

Conformal coatings are good for boards that aren't already contaminated. Not so good for already-contaminated boards. There are ways to clean contaminated boards to stabilize them, dry them and then coat them.

I use Marine connector silicon grease, a.k.a. O-ring grease in just about all electrical connectors. Displaces air, humidity and whatever else might be carried around in the air, like salt.

Raw and burned diesel fumes can be rather corrosive too. Keep fumes from diesel fuel cans/barrels and diesel engine/generator exhaust well away from your precious observatory and anything else you care about.

I only use stainless steel fasteners everywhere in all observatories and equipment, regardless of proximity to salt air.

To prevent galling and damaged/broken parts, always add a small drop of oil to stainless and aluminum threads before putting things together. 

I only use stainless wood screws in observatories with wood components. I never use nails whenever they can be avoided. Observatories are not static structures, they are dynamic machines with moving parts. Nails are just about always completely unsuitable for machines. When using nails, everything works loose over time.

I recommend using fiber optic communications wherever possible. Minimize damage due to ESD, GPR, RFI, etc. My preference is for 50 micron multimode. It is more tolerant of dirty connectors and such versus single-mode fibers. 

All USB connectors suck and are unreliable. Currently USB-C is the least horrible USB connector. USB-A is the most horrible. Just FYI.

Keep all copper conductor cables in an observatory as short as possible. I put NUC's on OTA's and control them remotely. 

I use big SSD drives in all observatory computers. Especially above about 2.5 km elevation. Mechanical drives have air cushion bearings that keep the heads near but not touching the spinning discs. Thin air is dangerous for them.

Never let any cable run openly across a floor. Copper conductor cables will be at greater risk from ESD & GPR. Fiber cables will be at risk of damage from being stepped on. Also a tripping hazard.

Leaving USB/Ethernet/etc. cables with one end unconnected laying on or near a floor in dry, static-prone climates is almost guaranteeing getting a USB/Ethernet/etc. port blown out by ESD.

I hope this helps.

"Always take the high road. There's less traffic."

-Christopher Erickson
Observatory Engineer
Summit Kinetics
Waikoloa, Hawaii


On Mon, Jul 4, 2022 at 1:43 PM Brian Valente <bvalente@...> wrote:
Hi Steve

I had to deal with this recently. One of the things I added was conformal coating to the circuit boards/electronics. It shields the boards from corrosion


On Mon, Jul 4, 2022 at 3:09 PM Steve Wilkins <stevewilkinsmail@...> wrote:
Yes that was my understanding. Good suggestion on the stainless, thanks, I do see some signs of corrosion on the small level on the baseplate; not too worrying as it’s not core to the mount’s function, looks like it might be plated steel. 



--

Join main@ap-gto.groups.io to automatically receive all group messages.