Al metal in the tank

[bkiba]

Randy

Is it ok to have aluminium metal touching my tank water? I'm trying to use this as a buffer between electronic temperature sensor IC and the water itself. Al has great thermal conductivity properties so a thin piece would be ideal. I will only be exposing about a 1 cm^2 area to the water for each of the 6 sensors.

LMK

thanks

 

[Randy Holmes-Farley]

I wouldn't recommend it. I'd use stainless steel or plastic.

FWIW, for heater/chiller control, you do not need a super fast response because the water changes temperature very slowly. I have some temperature sensors (thermistors) that seemed to eventually let water into them even though designed for submersion. I inserted them into thin plastic tubing (like air line tubing) long enough to stick it well under the water but still have both open ends of the tubing above the water surface. That has worked well for years now to control heaters and my cooling system.

 

[bkiba]

but I know that stainless will corrode in the salt water even, this is ok?

 

[BeanAnimal]

bkiba...

just use a plastic interface. Like we talked about in the other thread, and Randy eluded to here. There is no need for a metal interface for the speeds you need.

Again if you need to catch a 2 degree swing in 1-3 seconds, then you have a serious problem with your tanks heating, cooling system. On the otherhand to catch a 1-2 degree swing in a -15-30 seconds , plastic will be fine. It will likely be much faster than that.

Bean

 

[Boomer]

I agree with Randy and Bean. Also, it is the grade of SS. There was a marine store in Minneapolis were the guy custom built all the tank frames of SS. After years I saw no corrosion. The there is also Titanium

 

[Randy Holmes-Farley]

but I know that stainless will corrode in the salt water even, this is ok?

Depends on the grade, but some are OK. I have two float switches in my tank with SS arms that have been there more than 10 years. I can't see them easily to see if they are corroded, but they haven't broken yet.

 

[bkiba]

what grade would you recommend?

I use 316 a lot at work for medical applications (I figured this would be the best corrosiion resistance), but I've seen it rust after sitting in the lab sink for a while.

Like I said in the other thread the titanium has crappy heat transfer about 10% of Al. I will probably end up going with a plastic buffer as suggested. Maybe some soft silicone, has a high heat transfer.

thanks guys

 

[Randy Holmes-Farley]

316 should be OK. That's what I've been using for my float switchs arms.

 

[bkiba]

alright thanks again for the suggestions. Probably just going with some PLASTI DIP. Seems to be easy enough and should be water proof.

http://www.plastidip.com/consumer/index.html

 

[Randy Holmes-Farley]

Yes, that could be a fine option .