K-type thermocouples

[Swift Pint]

Ages ago before I really understood PIDs & PT100s etc, I got excited and bought a cheap PID from ebay. I thought it was a bargain. I then found out that it only works with K-type thermocouples.

Since then I've gone down the PT100 route & got my HERMS setup & working nicely. However I have a feeling that I should be using the K-type for something... I just cant think what.

I've read that K-types have a margin of error of about 2C. Has anyone had any luck with them? Any ideas what I should use mine for? Any uses I can come up with, either dont really need measuring or would be worth getting more PT100s for...!

:wha:

Oh and just out of interest, what sort of accuracy does a cheap glass thermometer get?

 

[Vossy1]

Oh and just out of interest, what sort of accuracy does a cheap glass thermometer get?

Very varied :shock: Go into your local HBS and look at all the GT's, you'll be lucky to get 2 reading the same :lol:

I've read that K-types have a margin of error of about 2C. Has anyone had any luck with them? Any ideas what I should use mine for? Any uses I can come up with, either dont really need measuring or would be worth getting more PT100s for...!

Type K's can vary across a range whereas PT100's tend to be fairly linear, so if a PT100 reads a true 0 deg c it's likely to read true at other temps, whereas a Type K may vary.
I used to 'calibrate' my type k's with an ice bath and boiling water and found them to be quite accurate at 0 but they could be out like you say by 2 deg nearer boiling.
It also depends what type K you have, class 1 or 2, this is also the same for PT100's.

I'd use the type K where the temp accuracy isn't that important. Having said that, 2 deg isn't that much really and it's not worth getting hung up over, though I wouldn't use it for checking mash temps, personally.

 

[Aleman]

Type K are typically used in Furnace applications where 2C at 600C is unimportant . . .indeed 2C at 200C (as in an oven) is only 1% error and could be considered unimportant . . . 2C at 50C is 4 % and that is where it starts to be important.

 

[pjbiker]

Oh and just out of interest, what sort of accuracy does a cheap glass thermometer get?

I had one that was rubbish, read about 2.5 degrees too low (compared with a digital one) which resulted in me mashing too hot and getting v high finishing gravities til I worked out the reason. OK if you calibrate it as Vossy suggests, ice bath-boiling water.