ITTSB.EU Blog Forum
ITTSB Blog Specific => ITTSB - Small projects by Kiriakos & User reviews => Topic started by: Kiriakos GR on February 04, 2013, 08:18:07 PM
-
I was having this quick experiment or test in my mind for some time now.
I wanted to find out how those identical made Agilent U1186A thermocouple behave up to 100 Celsius.
I wanted to see the BRYMEN BM869 how well it maintains it scalability with dual probes?
I wanted to see the measurement update rate in this dual temperature measurement mode, by monitoring a rising up temperature in the unit of time.
The test bed is simple, two K-Type probes and hot water.
The two ends kept together by plastic tube, and were almost touching the bottom of my Kenwood water heater.
One timer measured the time, which is 5 minutes up to the water boiling point.
I took pictures mostly from the interesting part that is the 60C up to the 100C.
As you can see the results are more than great with almost identical values.
The thermocouple needed around two minutes to recover for the 100C back to the room temperature.
At about the half of the journey the BM869 shown the Low battery indicator but no worries, it works with the new rechargable NiMH Tenergy centura 9V for about 8 months up to date ;)
-
Set No2
-
Really cool that the Brymen can take two Thermocouples! I like that a lot....
Settling time of about two minutes from around 100°C to ambient is kinda slow. When I used the Thermocouple with my Agilent meters on an oven or in boiling water (to get the right Temperature for a coffee ;)) it was settling back to ambient in about 10s after I took them out.
I really don't think that the thin wires of the TC could store that much heat to be that slow. In fact, that's what I like about TC's....they are really fast!
________________________________________
About your Tenergy 9V. Do you have a 9V charger that you can recommend?
-
About temperature recovery .. by removing the probes from the hot water at 100C the temperature dropped in 3 seconds at 50C and then started to drop more.
The truth is that I did not pay much of attention to record in detail the recovery time.
But imagine that about 15 centimeters of length of those probes, was in the water for some time, I believe that the insulation plastic slowed down a bit this process.
-
I just made me a coffee, and I did the test of deeping the probe for 5/S when the water is at 100C ,
and I did pull it out and measured the recovery time back to 15.5C in door. :)
-
About temperature recovery .. by removing the probes from the hot water at 100C the temperature dropped in 3 seconds at 50C and then started to drop more.
The truth is that I did not pay much of attention to record in detail the recovery time.
But imagine that about 15 centimeters of length of those probes, was in the water for some time, I believe that the insulation plastic slowed down a bit this process.
Exactly.... the insulation and the wire of the TC itself store some heat and give that away. So you'll have a decrease (it's logarithmic). The more mass of wire (thicker or longer), the more can be stored. The Temperature is measured on the wire interconnection (tip of the TC) anyway. So there is no need to submerge it deep into the water...except if you want to measure the temperature at that depth of course ;). The same happens if you try it reverse....drop in the TC into boiling water, and it need a while to settle.
As I said, TC's are mostly much faster than RTD's........ because they have less mass to heat up ;).