How to protect the DS18B20 from the elements
- Thread starter rmeldo
- Start date
Hobby shops and Rapid do various thin-walled metal tubing.
Maybe even B&Q?
Everywhere sells potting compound.
Some people even use silicone sealant or Araldite. Though I believe some epoxies get degraded by prolonged sunlight.
Remember not to have too much mass if you want reasonably rapid response.
And, obviouly, you will have chosen a suitable robust wire which doesn't get degraded.
Maybe even B&Q?
Everywhere sells potting compound.
Some people even use silicone sealant or Araldite. Though I believe some epoxies get degraded by prolonged sunlight.
Remember not to have too much mass if you want reasonably rapid response.
And, obviouly, you will have chosen a suitable robust wire which doesn't get degraded.
Andrew Cowan
Senior Member
The legs definitly need protecting - the silicon body does not. I protect mine by soldering on wires, then covering the legs in bathroom silicon sealant. It can be cut of if required, and if fully waterproof.
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BeanieBots
Moderator
Actually the body DOES need protection.
It can suffer water ingress which will effect accuracy and eventually result in total failure if actually immersed in water.
For a really simple quick/easy solution, pop into your local motor accessories store (very good one near the Grenadier pub just up the road from you) and get some "liquid metal".
It's a two part epoxy like Araldite but much tougher.
Also, I've got some spare suitable stainless tube if you want some.
Could pop a short length round to you. Not today but maybe tomorrow.
It can suffer water ingress which will effect accuracy and eventually result in total failure if actually immersed in water.
For a really simple quick/easy solution, pop into your local motor accessories store (very good one near the Grenadier pub just up the road from you) and get some "liquid metal".
It's a two part epoxy like Araldite but much tougher.
Also, I've got some spare suitable stainless tube if you want some.
Could pop a short length round to you. Not today but maybe tomorrow.
Abs BB.
Just covering legs will end in tears in prolonged damp exactly as said by BB. And that doesn't provide any physical protection from 'accidental handling' either
Encapsulating the complete thing is the best way, and, optionally there are potting compounds with improved thermal conduction (not electrical) if important. Probably doesn't matter and its a bit expensive for just half a teaspoon.
Full encapsulation also provides a bit of strain relief for wires too.
I remember getting some plated copper battery terminals which were a tube with one end squashed flat and an 'ole drilled. I used that for a thermistor in a project yonks ago. The hole made for easy mounting. But still not as good as thin-walled stainless.
Now, if BB is being generous with materials, I wouldn't mind some adhesive for Acetyl Copoloymer if you have some in the shed? After all, I did clean your car for you , though I forgot to polish the offside wing.
Just covering legs will end in tears in prolonged damp exactly as said by BB. And that doesn't provide any physical protection from 'accidental handling' either
Encapsulating the complete thing is the best way, and, optionally there are potting compounds with improved thermal conduction (not electrical) if important. Probably doesn't matter and its a bit expensive for just half a teaspoon.
Full encapsulation also provides a bit of strain relief for wires too.
I remember getting some plated copper battery terminals which were a tube with one end squashed flat and an 'ole drilled. I used that for a thermistor in a project yonks ago. The hole made for easy mounting. But still not as good as thin-walled stainless.
Now, if BB is being generous with materials, I wouldn't mind some adhesive for Acetyl Copoloymer if you have some in the shed? After all, I did clean your car for you , though I forgot to polish the offside wing.
BeanieBots
Moderator
Yes Dippy, thought I'd not notice the off-side
Anyway, my tubing is NOT very thin walled so won't give ultra fast response but is VERY durable. In a previous life it carried high pressure nitrogen.
As Dippy mentioned, the leads are just as important. You can't use any old bit of wire. I honestly don't know of a suitable type except some I already have which was taken from an existing outside insatllation. Even the readymade thermometers with "external" probes dissintegrate after a few years under water. I slip mine inside silicon air line for protection.
Anyway, my tubing is NOT very thin walled so won't give ultra fast response but is VERY durable. In a previous life it carried high pressure nitrogen.
As Dippy mentioned, the leads are just as important. You can't use any old bit of wire. I honestly don't know of a suitable type except some I already have which was taken from an existing outside insatllation. Even the readymade thermometers with "external" probes dissintegrate after a few years under water. I slip mine inside silicon air line for protection.
BB
Thanks for the tip about the potting compound.
For the tubing I have just stolen the tip from my colleague's pencil. (he is on holiday, the Bast**d, he won't mind) . It is thin walled so low thermal inertia. The other good thing is that it is closed at one end, so total damp proofing.
If someone wants to wash my car too, feel free to say. (what a great forum!!!). I can repay in kind. I have a bag of plaster and a paint roller that I don't need anymore.... and I'll make you a cup of tea.
Dippy, do you live nearby or you travelled especially to service BB's car?
Riccardo
Thanks for the tip about the potting compound.
For the tubing I have just stolen the tip from my colleague's pencil. (he is on holiday, the Bast**d, he won't mind) . It is thin walled so low thermal inertia. The other good thing is that it is closed at one end, so total damp proofing.
If someone wants to wash my car too, feel free to say. (what a great forum!!!). I can repay in kind. I have a bag of plaster and a paint roller that I don't need anymore.... and I'll make you a cup of tea.
Dippy, do you live nearby or you travelled especially to service BB's car?
Riccardo
BeanieBots
Moderator
I keep losing the tips from my pens. Now I know where they're going!
Good choice, if they can withstand saliva & teeth, I'm sure they'll cope with a little moisture.
Dippy made a special trip. So kind of him.
Good choice, if they can withstand saliva & teeth, I'm sure they'll cope with a little moisture.
Dippy made a special trip. So kind of him.
BeanieBots
Moderator
How do they make the teflon stick to the pan?
A couple of genuine questions.
1. "Bathroom" silicone? Doesn't the smelly acidic stuff do nasties to copper?
2. What's this wire like outside?
http://www.rapidonline.com/Cables-Connectors/Equipment-Wire/Test-Cable/Silicone-test-cable-23AWG/73359/kw/silicone
It's certainly very flexible, and pairs or triples
hold their "twist" very well.
e
1. "Bathroom" silicone? Doesn't the smelly acidic stuff do nasties to copper?
2. What's this wire like outside?
http://www.rapidonline.com/Cables-Connectors/Equipment-Wire/Test-Cable/Silicone-test-cable-23AWG/73359/kw/silicone
It's certainly very flexible, and pairs or triples
hold their "twist" very well.
e
ec:
1. Don't know, but the acetic acid business dissipates after the cure. Having said that, the 'proper' potting compounds make quite an issue about the curing process as there are a number of issues. Have a Google.
2. Don't know. Many durable cables use modified PVC and PTFE (and probably all sorts of wierd plastics) for outside use (damp, UV, temperature, schoolboys etc.)
So, have another Google. I don't think there is a one-size-fits-all answer.
I really don't know how non-stick is stuck. I'm sur someone can Google and pretend they knew all along. Now where is he?
My best frying pan before SKK was a made in France tefal, which finally failed after 10 years.
We had a couple of expensive stainless Meyers, both failed after about a year, non-sick very soft and eventually blistered. However, a Meyer Analon Pro (anodised al then coated) is proving to be very good too. Did some scrambled eggs this mroning, overcooked of course, and washing was no problem. Ten seconds with a cloth and Fairy Liquid. All a bit pricey though.
1. Don't know, but the acetic acid business dissipates after the cure. Having said that, the 'proper' potting compounds make quite an issue about the curing process as there are a number of issues. Have a Google.
2. Don't know. Many durable cables use modified PVC and PTFE (and probably all sorts of wierd plastics) for outside use (damp, UV, temperature, schoolboys etc.)
So, have another Google. I don't think there is a one-size-fits-all answer.
I really don't know how non-stick is stuck. I'm sur someone can Google and pretend they knew all along. Now where is he?
My best frying pan before SKK was a made in France tefal, which finally failed after 10 years.
We had a couple of expensive stainless Meyers, both failed after about a year, non-sick very soft and eventually blistered. However, a Meyer Analon Pro (anodised al then coated) is proving to be very good too. Did some scrambled eggs this mroning, overcooked of course, and washing was no problem. Ten seconds with a cloth and Fairy Liquid. All a bit pricey though.
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BeanieBots
Moderator
Silcon wire is certainly very good for test leads due to the extra flex, however, I've no data regarding degredation due to UV or moisture.
PTFE coated wire withstands just about anything you can throw at but NOTHING will stick to it so very hard to make a bond/seal with. Very tight rubber grommet is the only way I've managed it.
The wire I've used in the past came from a cheap external CCTV camera. It's black, four core and a bit stiff. Other than that, I've no idea what it is. Doesn't 'feel' like any other cable I've come across. Can't be expensive or there wouldn't have been 15m of it supplied with a £50 camera. Also, for some unknown reason, the local squirrels leave it alone. Unlike the very expensive satalite cable
What I can say, from experience, is that cheap hookup wire won't last a year outside.
PTFE coated wire withstands just about anything you can throw at but NOTHING will stick to it so very hard to make a bond/seal with. Very tight rubber grommet is the only way I've managed it.
The wire I've used in the past came from a cheap external CCTV camera. It's black, four core and a bit stiff. Other than that, I've no idea what it is. Doesn't 'feel' like any other cable I've come across. Can't be expensive or there wouldn't have been 15m of it supplied with a £50 camera. Also, for some unknown reason, the local squirrels leave it alone. Unlike the very expensive satalite cable
What I can say, from experience, is that cheap hookup wire won't last a year outside.
For my outside DS18B20, I used a short length of micro bore copper tube and epoxy resin to seal the sensor, leaving just a couple of millimetres of the plastic protruding, and then housed it into an old plastic 'thermostat' housing with the original guts removed...still allows the airflow around the sensor.
On a similiar note, why is 'abbreviation' such a long word??
lbenson
Senior Member
For outside DS18B20 I used about an inch and a half (given to me free by the hardware man) of 3/8th inch flexible copper tubing. End sealed with epoxy and then DS18B20 with blob of thermal compound on the end pushed in. Wired end then epoxied. Now you've got me wondering about the life of my wire.
westaust55
Moderator
knew a work colleage who went by the nickname of "PTFE".
Nothing stuck to him no matter how he stuffed up.
Nothing stuck to him no matter how he stuffed up.
If the DS18B20 is just being used for simple outdoors monitoring, then the first step is to position it AWAY from direct elements, perhaps under the sheltering roof eaves etc. Rapid thermal response will not always be needed of course either, so extra covers of plastic insulation/heat shrink etc are tolerable. IMHO it's pretty important to retain the ability to access sensor leads etc if need be.
Copper tubing encasing has merits too, much as outlined here, but I prefer sealed glass test tubes, or clear heat shrink as these suit inspection. You can even slip a label inside these too =>http://www.picaxe.orconhosting.net.nz/datds08m.jpg.
Copper tubing encasing has merits too, much as outlined here, but I prefer sealed glass test tubes, or clear heat shrink as these suit inspection. You can even slip a label inside these too =>http://www.picaxe.orconhosting.net.nz/datds08m.jpg.
westaust55
Moderator
Riccardo,
What is the application? For example is it a fixed loaction?
Weather stations use a Stephensons Box (or is that Stevenson - found both spellings when trying to verify).
They are used by Meteorology Dept's for official weather sites.
Louvered boxes, painted white in which Temp and RH equipment is located.
Keeps the UV and IR light off, no water entry (except maybe a cyclone (Tornado goes the other way) . . . . .
What is the application? For example is it a fixed loaction?
Weather stations use a Stephensons Box (or is that Stevenson - found both spellings when trying to verify).
They are used by Meteorology Dept's for official weather sites.
Louvered boxes, painted white in which Temp and RH equipment is located.
Keeps the UV and IR light off, no water entry (except maybe a cyclone (Tornado goes the other way) . . . . .
Andrew Cowan
Senior Member
I've never tried it, but maplins (and others) sell heatshrink with an adhesive lining. Heat it up, and it should be waterproofed and sealed (on wire joints, anyway). You can make your own lot of this by placing hot glue gun stick pieces in heat shrink.
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westaust55
Moderator
Heat Shrink sleeving
Heatshrink sleeving will work but a few things to keep in mind:
1. any sharp edges and the heat shirk will split or puncture so nice parallel solder conenctions to the leads is a must,
2. It does take a reasonable heat level. 1200 W Hair dirier will not be enough (be there. . . ) I (and most major electrical contractors who do work for me) use a gas bottle with fishtail burner.
3. Do not over shrink - will cause a lot of tension and cause the heat shrink to split at some later time.
Heatshrink sleeving will work but a few things to keep in mind:
1. any sharp edges and the heat shirk will split or puncture so nice parallel solder conenctions to the leads is a must,
2. It does take a reasonable heat level. 1200 W Hair dirier will not be enough (be there. . . ) I (and most major electrical contractors who do work for me) use a gas bottle with fishtail burner.
3. Do not over shrink - will cause a lot of tension and cause the heat shrink to split at some later time.
