These messages indicates that the Effective Range of the chamber is outside the normal boundaries that we expect for a chamber of that type and species. The Effective Range is the maximum/minimum allowable flow through the chamber's pneumotach based on its resistance. A higher (wider) Effective Range indicates that more flow can pass through due to less resistance, whereas a lower (tighter) Effective Range indicates that less flow can pass through due to more resistance.
First, check the relevant Application Manual and find the section on acceptable Effective Ranges:
If your Effective Range is higher/wider than the acceptable range, this is often due to the calibrator not being filled enough. The calibrator should be filled as precisely as possible to the Fill line on the sticker, not necessarily to the etched groove on the calibrator. Another reason is a leak in the chamber. A leak can develop over time due to the o-rings cracking, so check for this and replace any cracked o-rings from the maintenance kit. Remember that regular lubrication of the o-rings by the included silicon grease helps keep them good for even longer. A leak can develop suddenly if a fitting is forgotten and part of the chamber is "open". If a leak is not obvious, it can be checked by following the steps in this Knowledge Base article: https://support.datasci.com/hc/en-us/articles/360007406054-Leak-Test-Process-for-FinePointe-WBP-Chambers
Note: if you are seeing the "Nearing Unacceptable Range" message on a new chamber or new system and are confident that the calibrator is filled properly and there are no leaks, it may be that the chamber itself has a naturally larger range than normal. This is not a problem and can be solved with a file change on the computer by a Technical Support representative, but we will always want to verify the aforementioned possibilities first.
Note: if you are using an older system (before 2016) and just upgraded to FinePointe 2.4.6 or above, these Effective Ranges may be exacerbated by inaccurate calibrators or a firmware bug. Both were solved in 2016. Please refer to the following Knowledge Base to verify that you are using an accurate calibrator and newer firmware: https://support.datasci.com/hc/en-us/articles/360005361214-FinePointe-Accuracy-Improvements
If your Effective Range is lower/tighter than the acceptable range, this is sometimes due to the calibrator being filled over the Fill line. If the "Outside Acceptable Range" error happens suddenly with no warning and the effective range is significantly lower than normal, please check to see if the chamber portion with the pneumotach was submerged in water during cleaning. Remember, we do not want the screens within the pneumotach to ever be wet, so submerging the pneumotach in water will cause higher resistance and a lower Effective Range.
However, a gradually decreasing Effective Range over time is completely normal and occurs because of animal dander, fur, and moisture getting collected in the pneumotach screens. If you see the "Nearing Unacceptable Range" message after repeated use, and the Effective Range is slightly lower than acceptable, this means that you should change the screens on the Animal side of the pneumotach.
In both the above scenarios, please refer to the relevant Application Manual for the system you are using and find the section regarding Replacing Pneumotach screens.