Spike Brewing 12.5 Conical Fermenter Giveaway - Enter Now!

Home Brew Forums > Home Brewing Beer > DIY Projects > K Type Thermocouple vs RTD temperature sensor

Reply
 
LinkBack Thread Tools
Old 10-19-2009, 02:50 PM   #1
maxbing
Feedback Score: 0 reviews
Recipes 
 
Join Date: Nov 2008
Posts: 84
Liked 2 Times on 2 Posts

Default K Type Thermocouple vs RTD temperature sensor

I am about to pull the trigger on some PID temp controllers from Auber Instraments. I can't decide on the type of temp sensors to go with K Type Thermocouple vs RTD temperature sensor. RTD is a little more expensive but not enough to really matter.

Does anyone have any advice? Pros or cons of each?

Thanks

__________________
maxbing is offline
 
Reply With Quote Quick reply to this message
Old 10-19-2009, 03:03 PM   #2
Yuri_Rage
Gritty.
HBT_MODERATOR.png
Feedback Score: 0 reviews
 
Yuri_Rage's Avatar
Recipes 
 
Join Date: Jul 2006
Location: Southwest
Posts: 13,910
Liked 606 Times on 376 Posts
Likes Given: 54

Default

This link gives a nice comparison of the two: http://www.smartsensors.com/spec.htm

I've seen a lot of posts recommending RTDs for their higher accuracy and linear response. However, it's splitting hairs, IMHO. Both sensors are capable of less than +/-1% accuracy (effectively, less than +/-1.5 degrees at mash temps). For brewing applications, a decently calibrated thermocouple is just fine. I chose thermocouples for my rig, mostly due to the faster response time.

__________________
Homebrewed Blog..........YouTube Channel .......... Shirts, posters, etc
Yuri_Rage is offline
 
Reply With Quote Quick reply to this message
Old 10-19-2009, 03:05 PM   #3
conpewter
HBT_SUPPORTER.png
Feedback Score: 0 reviews
 
conpewter's Avatar
Recipes 
 
Join Date: Nov 2007
Location: East Dundee, Illinois
Posts: 5,109
Liked 40 Times on 35 Posts
Likes Given: 7

Default

In our application I don't think you'll see a lot of difference. Just make sure to match your controller to the type of temperature sensor you are going to get. Here's a chart that tells some of the differences
http://www.smartsensors.com/spec.htm

Edit:
darnit, beat by a couple minutes

__________________

"People should not be afraid of their governments. Governments should be afraid of their people." - V

Primary: Nothin
Secondary: Shady Lord RIS, Water to Barleywine, Pumpkin wine, burnt mead
Kegged: Crappy infected mild
Bottles: Apfelwein, 999 Barleywine, Oatmeal Stout, Robust Porter, Robust smoked porter, Simcoe Smash

conpewter is offline
 
Reply With Quote Quick reply to this message
Old 10-19-2009, 03:24 PM   #4
maxbing
Feedback Score: 0 reviews
Recipes 
 
Join Date: Nov 2008
Posts: 84
Liked 2 Times on 2 Posts

Default

Nice link,

Thanks guys.

one column made my decision for me...Ruggedness. other than that for the temps we are talking about both look like they would be fine.

__________________
maxbing is offline
 
Reply With Quote Quick reply to this message
Old 10-19-2009, 05:47 PM   #5
Sawdustguy
Feedback Score: 1 reviews
Recipes 
 
Join Date: Mar 2009
Location: Manorville, New York
Posts: 2,772
Liked 28 Times on 25 Posts

Default

Thermocouples are just a junction between two dissimilar metals where a RTD is simply a resistor that changes value with temperature. As the previous posters pointed out, for our purposes, it's a non issue. I went with a thermocouple because I found one, for not too much money that had a 1/2" NPT thread on it so I could screw it right into my keggle.

__________________

Guy

Sawdustguy is offline
 
Reply With Quote Quick reply to this message
Old 10-21-2009, 03:23 AM   #6
ILOVEBEER
Feedback Score: 0 reviews
Recipes 
 
Join Date: Sep 2009
Location: CA
Posts: 728
Liked 5 Times on 5 Posts
Likes Given: 1

Default

The tech at Auberins told me that the RTD coupler is a more accurate sensor. The price difference is not much. What I like about mine is that the actual 1/4" NPT probe is able to be removed from the probe via a quick disconnect. I did not plan on this, just discovered it after I ordered it (to be honest with you I had no idea what I was ordering) after talking to the Auberins tech....who I pissed off with all of my elementary questions.

__________________

Last edited by ILOVEBEER; 10-21-2009 at 03:27 AM.
ILOVEBEER is offline
 
Reply With Quote Quick reply to this message
Old 10-21-2009, 06:12 AM   #7
StMarcos
Feedback Score: 0 reviews
Recipes 
 
Join Date: Apr 2008
Location: Sebastopol, CA
Posts: 947
Liked 29 Times on 24 Posts
Likes Given: 1

Default

RTD is my vote. They offer more repeatable readings over time, and thus more robust in my opinion. I use 3wire RTDs that compensate for the resistance of the wires, which is important if you want to use long runs like I do. 4wire will compensate for different resistances between the wires.

Doorbell wire is a cheap source for wire... get some quick connectors from omega they are only a couple of bucks. Mine have 1/8mpt which I thread into 1/8fpt - 1/8straight thread. A silicone oring and a nut are used to make watertight connections. That's how I modded my stainless conicals to monitor temperature of the beer. I use a dial probe on the kettle... only used to gauge approach to boiling. Good luck!

__________________
StMarcos is offline
 
Reply With Quote Quick reply to this message
Old 11-01-2009, 06:39 PM   #8
Bigscience
Feedback Score: 0 reviews
Recipes 
 
Join Date: Sep 2009
Location: Woodinville, WA
Posts: 614
Liked 25 Times on 24 Posts
Likes Given: 4

Default Thermocouple Types

Any thoughts on the type of thermocouple to choose? J vs K vs T ect?

Also, I'm thinking about ordering from omega since they seem to have better quality than the Auberins ones I've gotten. The question is the configuration. I can get a connector on the end of the probe, braided line with a connector on the end of the line as well. Does anyone have the connector at the end of the probe? If so, do you like it?

__________________
Bigscience is offline
 
Reply With Quote Quick reply to this message
Old 11-01-2009, 09:03 PM   #9
Sawdustguy
Feedback Score: 1 reviews
Recipes 
 
Join Date: Mar 2009
Location: Manorville, New York
Posts: 2,772
Liked 28 Times on 25 Posts

Default

Quote:
Originally Posted by StMarcos View Post
RTD is my vote. They offer more repeatable readings over time, and thus more robust in my opinion.
Not true. You can't change Physics. A junction between between two dissimilar metals will always induce an EMF and unless the two metals change their chemical composition over time the EMF will stay constant.
__________________

Guy

Sawdustguy is offline
 
Reply With Quote Quick reply to this message
Old 11-01-2009, 11:14 PM   #10
StMarcos
Feedback Score: 0 reviews
Recipes 
 
Join Date: Apr 2008
Location: Sebastopol, CA
Posts: 947
Liked 29 Times on 24 Posts
Likes Given: 1

Default

It is true. There are more sources of drift in a thermocouple than in an RTD. They are also more accurate.

__________________
StMarcos is offline
 
Reply With Quote Quick reply to this message
Reply


Quick Reply
Message:
Options
Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
What type of thermocouple probe to use? stoutaholic Equipment/Sanitation 2 10-11-2010 01:46 AM
DIY Sensor Probes for RANCO Controllers gregdech DIY Projects 7 09-01-2010 02:12 AM
freezer sensor doug1395 Bottling/Kegging 1 10-02-2009 02:40 AM
This thermocouple?? kickflip_mj Equipment/Sanitation 3 04-03-2008 08:46 PM
Thermocouple or thermocouple wire source? e lo Equipment/Sanitation 22 11-08-2007 08:09 PM