Calibration with Dishwasher Thermostrips?

Need help with equipment usage or want to share your latest discovery?
BCN

#1: Post by BCN »

Has anyone of you ever tried to calibrate a PID espresso machine using these dishwasher Thermostrips inside the portafilter? https://www.telatemp.com/p/616/thermost ... -170f-180f

They have an accuracy of +-1 degree celsius, are HACPP compliant and pretty cheap. Could this be a solution for people who do not have a Scace device available?

They could be attached e.g. to a pice of plastic and put in the portafilter, then you raise the temperature slowly, pulling an empty shot each time and check for the change of indicator to black. If someone with an already Scace calibrated machine would do this it might be possible to see if there is a temperature difference and according to that many other people could set the Offset on their machines.

Please note that the strips I am talking about are irreversible and completely different from these reversible one, which are showing the temperature outside of the machine: https://www.orphanespresso.com/Group-Te ... _2133.html

I know that many people think it does not make sense to calibrate a machine. I respect that opinion, but I would not like to discuss it here. In my Victoria Arduino Eagle One Prima I have an App that allows me to share brew recipes with exact temperatures (e.g. 93.4 degree celsius, I know the machine is not that accurate) with other users. From my point of view the prerequisite for using/evaluating this function is a calibrated machine.

harrisonpatm

#2: Post by harrisonpatm »

Chef here, familiar with their use. Assuming that you don't mind the waste of these as a one-time use thing, and the associated cost therof, what you'll get is only a broad temp range, and maybe not even then. They're for health inspectors visiting a lot of different restaurants to keep in their kit and roughly check the function of the dish machine on the fly, to see if its coming somewhat close to hot enough to sanitize. These are designed to be run constantly for 1-2 minutes straight to get a reading. I can't say they'd measure the temp of the 15-30 second test pull. Even if they did, I'm gonna dispute the accuracy of their claim that they measure +-1 degree. If that was the case the display range would be in increments of 1 degree, not 5-10.

But now you've got me wondering about another non-traditional tool that might work in the absence of a Scace device. What if you pointed an infrared thermometer up into the group? I'd be interested to see that data.

BPlus: turning your coffee spirit
Sponsored by BPlus
randytsuch

#3: Post by randytsuch »

It will only tell you if the temp went over 180F, assuming the temp is high. Or it will tell you the temp is lower than 180F, which seems like you'd know if it was that low.

Not sure how much value that would be. If they had a higher temp version it would be better, but still not much resolution, only in 10 deg increments.

I remember sticking a thermocouple in the middle of the top of a puck to get temps, but you need something to read the thermocouple.
The wire was small enough to fit, and still lock in, if I remember correctly how I did the setup.

Randy

BCN (original poster)

#4: Post by BCN (original poster) »

The measurement would be more of a one time or once a year thing to calibrate the offset. Or for example after a firmware update, that messes up the offset handling (this is exactly what just happened to my machine). Therefore waste is not so much of an issue.

As these indicators are also used in controlled environments like hospitals, I would think their stated accuracy should be correct.

Measuring with an IR Thermometer would not help here, as you are not measuring the contact temperature with the coffee, but the temperature of the outside of the machine and that Temperature depends on various factors especially when you compare different machines. Also you cannot measure IR on a reflecting surface. Some people who tried put soot on the group to measure IR but the results do not tell you much about the inside.
randytsuch wrote:It will only tell you if the temp went over 180F, assuming the temp is high. Or it will tell you the temp is lower than 180F, which seems like you'd know if it was that low.

Not sure how much value that would be. If they had a higher temp version it would be better, but still not much resolution, only in 10 deg increments.
Randy
But this is exactly what I want to measure, if the temperature at some point of my measuring row goes over 82 Celsius (180F). I would start a lot lower than that and check after every "Shot" if the color changed. When e.g. at a PID setting on my machine of 77 Celsius the indicator goes to black, then I know my PID calibration is 5 degree off and adjust the offset by 5 degree. This setting is relevant for all other temperatures so the machine should be calibrated.

harrisonpatm

#5: Post by harrisonpatm »

It's an interesting proposition: are you saying that if you can calibrate a machine to know that when it says its pulling 175, its actually pulling 175, and you can assume that 200 is 200, and so on? I suppose that would make sense.

Thanks for the info on infrared, I haven't considered it reflecting. In my mind I was imagining it reading the water, but of course the grouphead screen would block it and reflect.

As for the comment on the strips being used in controlled environments like hospitals... This is not the forum to discuss the practicalities and politics of heath inspections. I'll just say that the food service portion of a hospital is not the same department as their cardiac ward, and the health inspector for a hospital one day is just as likely to inspect a McDonalds. Speaking from experience.