[NLRS] piezoresistive transducers, more

[Dr. Gerald N. Johnson]

I went googling for NIST's calibration capabilities. I didn't find them 
stated in an easy to read format for recent times. I did find in the 
1980s they were doing .04% which is not much more than that vendor's 
claim of .025%.

I also found a vendor of one with .015% claim with NIST traceability, 
for a mere $2439.00. Hand held with graphing, didn't say what kind of 
sensor it used.

I would think that a resolution exceeding that accuracy claim, would 
give a wandering reading, depending on wind speed, direction, and more 
on the pressure changes inside a building just because a door was opened 
or closed changing the volume of the building (or room) ever so slightly 
without considering the influence of wind in or out that door. Maybe 
even opening or closing a refrigerator door and swapping cool air for 
warm air would change the reading. And making the graph have fuzz on it 
that didn't actually reflect significant weather changes.

On the other hand, some NIST weight comparing techniques require 
recording the barometric pressure because it can affect weight compares 
in the ppm range of precision.

73, Jerry, K0CQ

On 12/25/2012 6:04 PM, Curt Peterson wrote:
>
>
> Perhaps one of you electronic experts can help me. I am considering buying adigital barograph that uses a "piezoresistive transducer" to determine atmospheric pressure. The manufacture  -  Aquatech Scientific Instr.  LLC claims their barograph has an accuracy of +/- 0.25 mb (or =/- 0.007 " hg) atmospheric pressure. The Company seems legit. but the claimed accuracy is very high. Are piezoresistive transducers that good ? ? Please reply. Thanks.  KC0FQZ  Curt Peterson
>