Calibration tolerance for data logger

[asteroid1122]

Hellow dears,

I am trying to calibrate Rotronic data loggers Model HL-20 which is used to record temperature and humidity using a Testo brand Huminator II but I am not sure about the calibration tolerance. In other words what is the acceptance criteria in the calibration.



Appreciate your support if you can share any reference in this matter.

 

[Eredhel]

This is completely out of my area of expertise but a quick google brought up the manual with a calibration section that has this:

"4. Maintenance
[FONT=Arial,Arial][FONT=Arial,Arial]4.1 Periodic calibration check
[/FONT][/FONT][FONT=Arial,Arial][FONT=Arial,Arial]
[/FONT][/FONT][FONT=Arial,Arial][FONT=Arial,Arial]Both the Pt 100 RTD temperature sensor and associated electronics are very stable and should not require any calibration after the initial factory adjustment.
Long term stability of the ROTRONIC Hygromer humidity sensor is typically better than 1 %RH per year. For maximum accuracy, calibration of the HL20 should be verified every 6 to 12 months. Applications where the data logger is exposed to significant pollution may require more frequent verifications.
[/FONT][/FONT]Note:
[FONT=Arial,Arial][FONT=Arial,Arial]Calibrating and adjusting the data logger typically require a humidity-temperature generator or other specialized equipment that may not be available to all users.
[/FONT][/FONT]Procedure for adjusting the data logger with the ROTRONIC HW4 software:
[FONT=Courier New,Courier New][FONT=Courier New,Courier New]o [/FONT][/FONT][FONT=Arial,Arial][FONT=Arial,Arial]Use cable AC3006 to connect the service connector of the data logger to the USB port of a PC with the ROTRONIC HW4 software installed. Note that the ROTRONIC USB driver must be installed on the PC as explained in the HW4 manual [/FONT][/FONT]E-M-HW4v3-Main
[FONT=Courier New,Courier New][FONT=Courier New,Courier New]o [/FONT][/FONT][FONT=Arial,Arial][FONT=Arial,Arial]Start HW4 on the PC and search for the data logger (HW4 Main Menu Bar > Devices and Groups > Search for USB Masters).
[/FONT][/FONT][FONT=Courier New,Courier New][FONT=Courier New,Courier New]o [/FONT][/FONT][FONT=Arial,Arial][FONT=Arial,Arial]After finding the data logger with HW4, expand the device tree to see the data logger functions. Select [/FONT][/FONT]Probe Adjustment[FONT=Arial,Arial][FONT=Arial,Arial].
[/FONT][/FONT][FONT=Courier New,Courier New][FONT=Courier New,Courier New]o [/FONT][/FONT][FONT=Arial,Arial][FONT=Arial,Arial]For further instructions see HW4 manual [/FONT][/FONT]E-M-HW4v3-A2-001 "

 

[asteroid1122]

Thank you my friend for your response. I have seen the manual but I didnt find anything regarding the calibration tolerance.

 

[dwperron]

I am afraid that you are "upside down" on the tolerances of the instruments involved here.

Your Rotronic has temperature accuracy of 0.3°C and humidity accuracy of 0.8% to 60% and 1.3% from 60 to 100%.

The Testo is accurate to 0.2°C, but only accurate to 1.5% RH.

The Rotronic is more accurate than the instrument you are trying to calibrate it with. This is happening more and more these days with humidity calibrations. The good old 4:1 ratio is getting harder to achieve, in cases like this it is almost impossible.

A couple of suggestions would be either to send the Rotronic out for calibration, or to limit its accuracy to something the Testo can handle. I would not use the Testo for anything with a tolerance less that ±3%, because that still only gives you a 2:1 accuracy ratio.