Are 'waterproof' DS18B20 sensors really waterproof?

[rkhanso]

I searched the forum first and didn't come up with an answer....

I bought a 10-pack of 'waterproof' DS18B20 sensors off eBay. I'm wondering if these are really waterproof, or if I should add some silicon caulk at the junction of the stainless steel probe and the rubber shrink tubing just to be safe? I planned on putting one in the fermenting bucket to monitor the temp during primary fermentation.

Here are the probes I bought:
http://www.ebay.com/itm/272227289398?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT

 

[Tiber_Brew]

Did the seller give any description of an IP rating, i.e. IP66, IP67, etc.?

 

[Leadpencil]

I would use a thermowell. No sense in taking chances.

 

[day_trippr]

The short answer is "probably not for long".
I wouldn't test that...

Cheers!

 

[Kent88]

I think I've seen ds18b20 sensor wires being sold that were described as water-proof and safe for contact with food.

Wish I could remember where I saw that. Probably isn't much help without the name of the seller or link.

 

[bruce_the_loon]

That's standard heat-shrink tube over the joint, I'd be unlikely to trust it submerged at any depth. It may have shrunk visually, but especially on the wire side, it might not have sealed enough to prevent capillary wicking.

Silicone caulk on both ends of the heat-shrink tube might work as long as you get it evenly spread on the joint edge.

What might be a better idea is to get some new heat-shrink tube of the right size, remove the existing tube, cover the wire joint to the sensor with silicone caulk and then shrink the new tube over the silicone starting from the middle so that the silicone is forced into both ends of the heat-shrink.

 

[mattd2]

This probably doesn't help you since you have already bought them but I always considered these sensors to be sold as waterproof from the pint they are install in a short 50mm thermowell already... you just have to figure out a way to mount that 6mm thermowell into you fluid. I have used 1/2" NPT 6mm compression fittings which I drilled out to 6mm all the way through the fitting with good success. Only issue is you only have about a 1/2" stick out past the end of the NPT thread (an virtually nothing on the outside - to the point of needing to cut back the heat shrink on some!).

 

[ame]

I think the heat-shrink joint is waterproof, but not particularly good. I have tried a couple of things. First, remove the heatshrink, then slide on a short piece of silicone tubing. The diameter must be a snug fit for the wire (which is smaller than the stainless steel cap). The silicone tubing will grip the wire on one side and the steel cap on the other and cover the joint.

If you are happy submerging the wire itself in your beer then you're done. The stainless steel cap and silicone tubing should be inert in your beer.

If not, the second suggestion is to either get another silicone tube, big enough to cover the first short piece and the rest of the wire, or, if the wire is quite thin, a long piece of tubing to cover the wire and the joint and the cap.

 

[rkhanso]

I bought some FDA approved hose with 1/4" ID. The store didn't have any plastic plugs for the hose to seal is up on the end that goes into the bucket.
Can I just take some 100% silicone caulk (I got the kind with NO mildew preventative on the label, just silicone caulk) and put about 1" inside the tube at one end to seal it up - and then put the temp probe in through the other and stick the hose in the bucket?

The heat shrink that goes over the metal probe part makes it too big to put into the hose, so I'd have to cut that short bit of heat shrink off to get it to go down into the hose.

 

[rkhanso]

After a little further research, I'm not going to use the 100% silicone caulk I bought at Menards.

I'm going to be going to the pet store and get some aquarium silicone sealer.

 

[cegan09]

You probably don't have to deal with any additional sealing at all. Cut the shrink tube off and see what's under it. Every one of those that i've bought has been properly potted at the joint between the wire and metal. The shrink tube is just there for who knows what reason, probably strain relief on the wires.

I cut the shrink tube off my first one because it didn't fit in my thermowell with it on. I often fill my thermowell with sanitizer to ensure a better thermal connection between the thermowell and sensor. Never had a problem.

 

[rkhanso]

You probably don't have to deal with any additional sealing at all. Cut the shrink tube off and see what's under it. Every one of those that i've bought has been properly potted at the joint between the wire and metal. The shrink tube is just there for who knows what reason, probably strain relief on the wires.

I cut the shrink tube off my first one because it didn't fit in my thermowell with it on. I often fill my thermowell with sanitizer to ensure a better thermal connection between the thermowell and sensor. Never had a problem.

Thanks for that suggestion cegan09. I did as you suggested and yes, it appears that there is a good seal at the SS end of the probe. I'll leave it as-is and put it in water as a test for a week and see if it stops working. If it works OK as-is, I'll just sanitize it and stick in the fermenting bucket as-is the next time I brew.

 

[bordev]

From experience I van tell that they are not water proof especially on high temps.

 

[Sadu]

I find these work well for several batches then they start to give bad readings. When this happens you beer can get very hot/cold and its bad times all round.

 

[rkhanso]

It's been a few days and the two sensors I have in the water are still working OK. It's just room temperature water - and I don't anticipate doing anything much higher than that anyway - when fermenting. When I get to building a HERMS system, thermowells will be expected anyway.

When using for fermenting next time, I'll probably take off the little piece of heat-shrink tubing and put a thin layer of aquarium silicone at the metal/wire junction of the sensor and call it good enough. I bought a 10-pack of sensors off ebay so if some go bad, I'll have some backups handy.

 

[cegan09]

I've had one submerged in water for over a year. Forgot about it honestly. It's in a fridge and I use a glass of water to get a stable temp reading (to mimic what things in a bottle are doing). It's still going strong.