The applications I'm thinking of are more along the lines of critical process temperatures loops that are "calibrated" annually, and have calibration tolerances associated with them. Throughout this research I've been asking myself how a "single-point check" can satisfy our needs as some have...
The first reference is a 10-page document, but I've highlighted the pertinent material. With this material in mind - including the fact that the first reference refers to temperature elements (TCs/RTDs) as the "weak link" with regard to accuracy - I don't see that a "single-point check" would...
Sorry, I thought I posted two references, but I suppose it only allows one file per post. Let me try this one again...http://files.engineering.com/getfile.aspx?folder=88dd5dbe-78bf-459b-a7b1-e842b4e2fd5b&file=Selected_Slides_from_ISA_training.docx
electric pete
I've attached my references that initially supported my suspicion that thermocouples and RTD's drift. Can anybody attach other references/data to the contrary, because I would seriously love to see them...
Thanks for the input guys! It is much appreciated! Everything piece of information I've come across leads me to believe that the "single point check" tells us little to nothing about the percent error in the loop, especially with the elements being the "weak link". Thanks again, and take care!!
Does anyone use a "single point check" to verify the output of their thermocouples and RTDs (basically checking to make sure the element is reading something), then use a TC/RTD simulator to check the rest of the loop? Everything I've read indicates that RTD's drift, and thermocouples drift...
We want our TC instruments calibrated to properly reflect process temps. As far as the other two questions, I hesitate to call this a blanket procedure, but we do want to have calibration prodedures in place that will be applicable to the biggest percentage of TCs on site. Obviously the accuracy...
Yeah, when I said TC calibration I was referring to the entire loop. Sorry, I guess I should have more specific. I can't find anything anywhere that says it is necessary to remove the thermocouple to check it, as long as it is operating correctly at the process temp. It looks like we can use...
Some people at work are suggesting the use of single point calibration in-place to calibrate our thermocouples/RTDs, and prevent damaging them through removal. Others are saying that this isn't effective because it doesn't give you at least one other point to set 0-point and span. Does anyone...
