Details of my digital thermometer setup for monitoring pan and stack on hobby evap

[maple6275]

Hey gang,

Just wanted to share some quick notes of the digital temp monitoring setup I came up with for my new rig. After trying a 5" analog dial and finding it didn't fit my pan well (stem too short,) I decided to go the custom route and piece together something to monitor both syrup pan and stack simultaneously.

The thermometer is a 2-channel unit from ThermoWorks (model TW8060), which accepts any K-type thermocouple and can monitor two probes simultaneously. To that I connected two 7" high temperature probes (model 113-420-MC). Each probe has a 8x1.0 metric threaded base. For the pan mount I drilled/tapped a matching metric threaded hole into a standard 1/4 NPT stainless plug, so that now screws right into the factory pan port. For the stack I just drilled a hole through and fastened the probe in with nuts on both sides. One problem I found is that the stack temp is too hot for the probe wire insulation... while the probe is rated to 2000F, the insulation on the wire coming from the mount is only safe up to 500F. So I have a couple melted spots on the insulation. I had to rig up a little stainless wire "cord keeper" to keep the cable from bumping against the stack in one spot.

To mount the thermometer to the pan, I used Loc-Line, which is a fantastic ball-and-socket tubing orginally designed for directing cutting fluid into machining operations. But it also works great for repositional mounting setups. Conveniently, there are also Loc-Line 1/4 NPT fittings, so I was able to screw the arm directly into the other pan port. Then I epoxied a 1/4-20 bolt into the end of a 1/4" Loc-Line nozzle, which screws into the mounting socket on the back of the thermometer. Everything I needed was in the $9 kit part number 40413.

Here are links to all the parts for those interested:
http://thermoworks.com/products/handheld/TW8060.html
http://thermoworks.com/products/probe/tc_imm_gen.html
http://www.loc-line.com/quarter-inch.php

Happy sugaring!



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[TerryEspo]

Looks pretty darn professional if you ask me. Nice job.

Thanks for sharing.

Terry

[Sugarmaker]

I agree it looks great! Nice evaporator and invisible sugarhouse too! :) Just kidding! Great looking rig! Nice steam!
Regards,
Chris

[Bucket Head]

I like that setup! Nice job.

And we had an invisible sugar house for years. Or as another syrupmaker called it, "a sugarhouse made of glass". And I added, "and with a roof that leaked every time it rained". Lol!

Steve

[DrTimPerkins]

The thermometer is a 2-channel unit from ThermoWorks (model TW8060), which accepts any K-type thermocouple...

Looks like a nice setup. One thing to be careful of....although Type K Thermocouples can resolve down to about 0.1 deg C, the tend to have fairly modest accuracy of about +/- 2 deg C, which at the boiling point of syrup is about 2 deg F, meaning that if you draw off syrup at 219 deg F, it could be as low as 215 or as high as 223 deg F The specs on that particular unit http://www.thermometricscorp.com/thertypk.html are better, at about 1 deg C, meaning they probably used what is called "Special Limits of Error" thermocouple wire, however that still means at an indicated 219 deg F, the actual syrup temp could range from 217-221 deg F even with the unit functioning perfectly. It is simply a limitation of the type of sensor system you are using.

To be sure you're getting good temperatures, I'd put the probe end in boiling water every week or so to be sure that you're getting close to 212 deg F.

Different "types" of thermocouples (indicated by the wire color and composition) have different levels of accuracy, which can also vary depending upon the temperature range you are using. Type K (yellow) is the most common because it is inexpensive and has a fairly broad range of useable temperatures.

Thermistors have much better limits of error of about 0.1 deg C, which is typically close to the resolution limit.

[maple6275]

Great info Dr. Tim, thanks! That Thermometrics site is very informative. Regarding accuracy I did find this on the Thermoworks site:


Unless otherwise noted, ThermoWorks employs high performance thermocouple wire with tighter tolerances than Special Limits of Error wire over common industrial ranges in its probe construction. Probe tolerances are listed below: Type K: ±0.9°F (0.5°C) from 32 to 212°F (0 to 100°C)
So combined with the meter accuracy of ±0.1% reading + 1.4°F, I guess that gives a system accuracy of ±2.5°F at 219°F? Anyway, close enough for government work and easy to get used to.