I keep running into this kind of thing.
There is a recurring question we are asked as instrument manufacturers:
"Is my equipment working OK?"
This is of particular concern when a production process seems to be off standard.
QC says: "Clearly Process Problems" 
Production says: "Bad Test Results"
These challenges arise often.
What to do?
Must we call in our outside certifier, send it to the manufacturer for calibration and/or run it on a known standard? What else can resolve this issue? Most of the solutions can take hours if not days to obtain. With a measure of analysis, equipment know-how -- and a bit of diplomacy -- the dilemma can be resolved on-the-spot.
The first option is a quick test to determine if the equipment is working properly, which answers the questions:
Is the Instrument Lying ?
Is QC right or is Production right?
Another major annoyance is when results don't seem to match between instruments of the same type. The initial conclusion is that all but one is lying, but which one?
Run the quick test to determine if each instrument is working properly. If a problem is found in one or more, the answer is fairly clear.
If all instruments pass the quick test, we are then confronted with a mystery that impels further investigation:
- Are the testing environments different?
- Are the product samples identical?
- Are the test parameters the same?
- Can the differences be duplicated with different operators?
If answering these questions do not resolve the mystery, it is clear that we are being lied to by one or more of the instruments. However, we must keep looking for some outside influence. ---- Need we find someone who can perform magic?
Yet another challenge arises when multiple labs are convinced that a test instrument is lying about given results. This can happen when the Corporate R&D people, a new outside lab or new QC staff determine that an industry standard test will be needed for samples. Frequently, this test will be off-site or the results will take hours if not days to obtain.
This is a major quandary.
We are faced with issues that require careful analysis of testing method differences, product sample reaction to these different
methods, environmental differences between test locations and strongly biased opinions. Finding rational answers to the "Is my instrument lying?" question is tough. A bit of luck is always welcome.
I would like to hear of your experiences with Lying Test Equipment and how you solved these problems. Comment about that here or email me at artgatenby@cscscientific.com.
I will share these experiences in future rants.
Art
P.S. These kinds of things happen for Moisture, Particle Size and Surface Tension instruments. No area of measurement escapes the question: Is My Instrument Lying to Me?
