We run a lot of non-calibrated RM Young 43347-IX PRTs for air quality monitoring and have run into a bit of a conundrum. I typically use ShortCut to create the framework for our programs, but it seems like it doesn't quite jibe with other sources of information in this case. When creating a program for the CR6 or CR3000 to sample the 43347-IX ShortCut uses the older PRT instruction instead of the newer (so presumably better?) PRTCalc. The help file claims PRTCalc has superceded the older instruction, but clearly that hasn't made its way to ShortCut. As such, I've simply followed the programming instructions in the CSI manual for the instrument and used the PRTCalc instruction. However, we've recently been having a hard time getting one of the PRTs to pass the +-0.5C three point check required by EPA. The site operator reached out to support and was informed about a discrepancy between the instrument manual and ShortCut for what the multiplier should be. He was advised to use what ShortCut outputs, which is 1.0267, vs. the manual which states 1.0. The latest manual (9/19) indicates that the PRTCalc instruction should be used, so my question is should I be using PRTCalc with the ShortCut multiplier, or should I be using the dated PRT instruction as output by ShortCut? I'm not versed enough in the details to know how PRTCalc is better, but the difference in the two multipliers certainly seems significant.
After digging deeper, it seems like perhaps the addition of the variable "Type" to PRTCalc might address the discrepancy. Using the Type 5 recommended in the instument manual looks like it changes the alpha (aka temperature coeffficient) from the old catch-all of 0.00385 to RM Young's specified 0.00375. The difference between 1.0 to 1.0267, and between 0.00375 to 0.00387 both seem to be 2.67%, if my arithmetic is right. Can anyone confirm that this removes the need to make the multiplier 1.0267?
To close this out I received an prompt email from support which read:
"We went through this. Your math is good, apart from the typo. Those are equivalent. We're looking into updating shortcut to avoid potential confusion in the future. We are recommending that you use 1.0 as the multiplier."
The second to last sentence from my second post should instead read:
"The difference between 1.0 to 1.0267, and between 0.00375 to 0.00385 both seem to be 2.67%, if my arithmetic is right."
I confirmed with a follow-up email that the advice is to use the 1.0 multiplier with the PRTCalc instruction.
Much thanks to David-Scott Rollins for keeping up the excellent customer service I always get from CSI!