Saw this later...
-----snippo-----
Subject: Liquid in Glass Thermometers, NATA position
Date: Thu, 25 Mar 1999 09:57:52 -0500 (EST)
Date: Wed, 24 Mar 1999 08:32:46 +0800
From: "Carman, Herbert" - health.wa.gov.au
Subject: RE: Calibrate/verify glassware
Liquid in glass thermometers can be checked for changes in the bulb volume over time by a single ice point check. The ice point check is suitable for checking change in the glass elasticity over time. The scale calibration is used to check the scale has been etched onto the glass in the proper place and should not change. Any change in ice point should be linear over the scale. NATA (Australia) require complete calibration of reference thermometers every 10 years and ice point checks every 6 months.
-----Original Message-----
Sent: Tuesday, March 23, 1999 10:40 PM
Subject: Calibrate/verify glassware
Moderator Note,
NIST publication NUST/SP-819 "A Procedure for the Effective Recalibration of Liquid-in-Glass Thermometers" states that high quality liquid-in-glass thermometers require only one complete calibration in their lietime. It is possible to avoid the usual requirement for complete recalibration of the instrument by recalibration of a SINGLE previously calibrated temperature. The need to recalibrate is due to the gradual relaxation of residual mechanical strains in the glass that have significant effect on the volume of the bulb. Recalibration of a SINGLE point provides reliable indication of the effect of this change in volume and provides a means for the accurate adjustment of the remainder of the scale. This is how to deal with thermometers. I would think that other glassware would exibit similar strains.
Greg
-----The REAL Original Message-----
--> From: "David Smith"
Date: Mon,
--> 22 Mar 1999 13:29:20 -0500 Subject: Calibrate/verify glassware
-->
--> Hi Greg, Can you provide me with some tips or suggestions on
--> calibrating / verifying burets, sacchrometers,etc.? How do I decide
--> if it is necessary? When the test points can't be altered due to
--> being etched in place, is a calibration check necessary? I have been
--> trying to keep a check using weight comparison; 1grm = 1ml distilled
--> water. This is difficult to justify accuracy. I am puzzeled with
--> this, give me a suggestion if you can, thanks Sincerly, David
--> Smith...