Re: Calibration/Verification of Rotameters

[Bernard L Cohen <blc+@pitt.edu>]

On Fri, 6 Oct 2000 dennis.hadlock@srs.gov wrote:
> 
> All,
> 
> I would like to know how often you calibrate/verify the rotameters 
> associated with air sampling equipment at your facility and to what 
> accuracy.  This would be for both installed and mobile air sampling 
> systems/equipment.  We are currently calibrating our rotameters annually 
> with a +/- 15% accuracy and would like to try and justify a longer 
> calibration period.

	--I calibrated rotameters by inverting a beaker with calibration
markings filled with water and placing it in a water bath; I then ran a
hose from the rotameter thru the water bath and up into the beaker. The
air pumped thru the rotameter displaces water causing the water level in
the inverted beaker to fall and the surface of the water read from the
calibration markings tells you how much air was pumped thru the rotameter.
The time required to pump this volume of air then gives the desired
calibration. The entire operation takes less than 5 minutes and it seems
to me that it should be quite accurate, surely better than 15%. Since it
is so easy, I don't see why you would hesitate to do it much more often
than once a year.
	Am I missing something here?

Bernard L. Cohen
Physics Dept.
University of Pittsburgh
Pittsburgh, PA 15260
Tel: (412)624-9245
Fax: (412)624-9163
e-mail: blc+@pitt.edu


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