posted 20 March 1999 07:51 AM               

Dave:

I really don't have any experience with glassware. We'll see if anyone here on the forum has any expddrience in glassware.

I also suggest you contact:

Greg Gogates
ListServe = [email protected]

posted 23 March 1999 02:40 PM               

----------snippo----------

From: "David Smith"
To: [email protected] 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

----------response----------

Subject: Calibrate/verify glassware
Date: Tue, 23 Mar 1999 09:40:16 -0500 (EST)
From: Greg Gogates
To: [email protected]

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

posted 05 April 1999 07:46 PM               

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Subject: Liquid in Glass Thermometers, NATA position
Date: Thu, 25 Mar 1999 09:57:52 -0500 (EST)
From: Greg Gogates
To: [email protected]

Date: Wed, 24 Mar 1999 08:32:46 +0800
From: "Carman, Herbert"
To: 'Greg Gogates'
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-----

From: Greg Gogates [mailto:[email protected]]
Sent: Tuesday, March 23, 1999 10:40 PM
To: [email protected]
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-----