Sika 18600E Dryblock Temperature Calibrator - Teardown, Pictures, Testing.

[beanflying]

Ever wondered if your Temperature measurements are accurate?

I have been casually looking for one of these for a long while to test Thermocouples, RTD's and other Temperature measuring devices. Below Freezing and from 0-100 can be done with reasonable accuracy using more conventional cludges such as Ice/Water or a combination of both. For commercial Ovens, Kilns or one of the areas I play with Coffee Roasters being able to accurately test measurement devices well above that are needed.

This example turned up on the other side of Australia out of Perth and was what I consider a bargain at $150USD (only bidder  ) to my door with a range of different diameter inserts compared to $700-1k generally without inserts/blocks. Its only downside is for higher temperature kilns as it has a limit of 600C but for what I do not really an issue and above that most of the common thermocouples are 'reasonably' linear so if you track them below fairly safe above will be close. If I develop a need for higher temperature calibration then back to the bay of evil again.

I will get around to putting a more accurate 4 wire RTD on it over the next few days but overall it while it is well out of current NATA (NIST) Cal it seems to be close to its +-1C accuracy spec with +-0.1C stability.

Closest currently available model (0-200C) https://www.sika.net/en/products/test-and-calibration-instruments/temperature-calibrators/series-tp-basic/item/965-temperature-calibrator-type-tp-18200e.html#technical-features Programming is simple and the operation manual is fairly much ok to use on this model.

Basic construction is made up of a hot and an electronic side kept apart by a small airgap but the outside case remains cool even at fairly high temperatures on both so the electronics is really only at ambient. The Spagetti will be getting some attention or some cable ties at a minimum The main Block takes an age to cooldown so you really want to take your calibration points on the way up. More accurate testing to come.

[beanflying]

The Manual for this particular one doesn't seem to be available online but a quick few emails to and from Sika got me what I need. I do have the calibration procedure for a slightly earlier model and if it works I will add it here too.

Spent a little time with some 800 and 1200 wet and dry removing many years of crud from the blocks. They get locked in place effectively by the expansion of the main block as shown above when heated. The level of unclean made them very hard to remove with the hook device without quenching the inner block with water to shrink it even when cooled.

Specified cool down time from 400'ish to 100C is 1 hour 

[beanflying]

More research and to and fro from SIKA. The controller for this and other models is made by TECNOLOGIC and it has available RS485 serial comms using MODBUS-RTU base. I will look at some sort of automation for it for automatically characterising TC's and RTD's in the future.

Controller Manual and Protocol guide is below to keep it all together.

[beanflying]

More clean up of the unit and making sure the Brass blocks don't get to knocked around in future with a solid 3D printed case. If anyone is interested in the STL files just let me know.

Nice snug fit and doesn't actually need any lock mechanism fitted to keep it all together.

[nfmax]

Weirdly I just happened to have almost simultaneously acquired a 'mini' dry-block calibrator, made by TMS Europe originally for their own internal use. Only covers 40˚C - 200˚C, and has a fixed block with a range of useful-sized holes. Nothing like as good a deal as @beanflying managed to score, but significantly less than they usually go for here - especially refurbished & recalibrated by the original manufacturer.  It's a dinky little thing, 160mm x 135mm x 50mm. I checked it out over the entire range, using my semi-standard PRT probe, and it is within 0.5˚C all the way. Very stable too, once it settles.

The only real drawback is the notoriously opaque Eurotherm controller UI!

The design was subsequently refined, and is now a commercial product: https://tmseurope.co.uk/products/calibration-equipment/dry-well-block-calibrators-temperature/bc2001

[beanflying]

'Cute' or as much as a lump of heated metal can be I did look at some of the mini Calibrators with fixed wells a while ago. For a lot of the 3-5mm diameter range devices they work well. The 880 Euro new pricetag isn't to much of a sticker shock compared to the likes of Omega, Fluke and Sika either.

Depending on how the interface with the current controller goes I may even look at swapping it out for something different entirely or at least making something to test and revert back if the original is better. It could be hacked from an Arduino and a Maxim 31865 https://datasheets.maximintegrated.com/en/ds/MAX31865.pdf which I have used on other jobs in the past.

Because I have this one I am now looking at Ice Point Calibrators 

[nfmax]

Next thing you know, it will be a triple point cell! Kelvin-nuttery lurks...