As we approach the 21st century, the need for qualified calibration laboratories has increased. More applications require the use of an instrument calibrated and traceable to NIST (formerly NBS). To meet this ever growing need, MILLER & WEBER, INC. has established a state-of-the-art laboratory with full time, highly qualified, trained personnel. We have technical representatives sitting on ASTM Committee E 20.05, Liquid-in-Glass Thermometers and Hydrometers, and our members are active in writing and updating the ASTM specifications dealing with Liquid-In-Glass Thermometers. Our President has been a member of and served on ASTM Committees for over 30 years. Our Technical Director has been a member of E 20.05 for over 5 years. MILLER & WEBER, INC. issues three types of written Certifications: Report of Calibration, Certificate of Accuracy, and Certificate of Conformance.

1.The Reports of Calibration issued by MILLER & WEBER, INC. are traceable to NIST and show corrections to be applied to within one tenth of the smallest scale division of the instrument. All test temperatures are carefully attained using microprocessor controlled equipment. Readings of the thermometer being tested are done by a process which virtually removes any chance of human error. Corrections to be applied, as stated on the Reports, are generated by computer. For immediate shipment of thermometers with Reports of Calibration, please go to that section of our catalog. <Therms w/ Reports>

2.The Certificates of Accuracy issued by MILLER & WEBER, INC. are verifications of accuracy and are traceable to NIST. They do not show the corrections to be applied.

3.The Certificates of Conformance issued by MILLER & WEBER, INC. are available at no cost and state thermometers in question are within the specifications supplied (ie NIST, ASTM, SAMA). This Certificate does not make the thermometer NIST traceable.

 

Any other instrument in our catalog can have a Report of Calibration issued. We will also certify your instruments on request.

The choice of calibrated temperatures is determined by the end user/customer. However, we suggest using the following guidelines.

A well calibrated standard may be used between known calibrated temperatures using algebraic interpolation. For this reason, the number and choice of calibration temperatures is critical. If the user has only one critical temperature, the Report of Calibration need only show that temperature and the ice point (if the thermometer has one). However, using this method, the thermometer most likely cannot be used at other temperatures with known accuracy and Algebraic interpolation is invalid.

If the thermometer bears the ASTM designation, we suggest using the Calibration and Verification Temperatures found in Table 3 of ASTM E-1. These temperatures, and standard emergent stem temperatures, if applicable, have been specified for best compliance with the ASTM Test Methods.

If a non ASTM thermometer is chosen that has no standard calibration and verification temperatures, we suggest calibration at every 100 lines. Therefore, a thermometer in 1° divisions will need calibration every 100° and a thermometer in 0.1° division will need calibration every 10°. The ice point (0°C or 32°F), if available, should always be included. The 100 scale division rule is usually valid for thermometers graduated not above 200°C. This will yield an interpolated value with an uncertainty of approximately one half scale division. If uncertainties in interpolated values of one tenth to two tenth of a scale division are required, the calibrated temperature interval will need to be reduced to 40-50 lines. An instrument graduated above 200°C should have an interval of 50 lines to achieve the one half scale division uncertainty. Again, for a better uncertainty of one tenth to two tenths of a scale division, the interval will have to be reduced to 20-25 lines.

Our calibration services take between one and two weeks. This is because our Certification process meets the strict quality controls of ISO Guide 25 and ASTM E-77 (as well as other quality standards).

Each instrument, either ours or yours, is given a thorough visual inspection before it is tested. It is inspected to make sure that there are no residual strains in the glass. The lines and numbers are checked for uniformity and placement and the capillary clearances are checked. The mercury or other fluid is then drawn down into the bulb (out of the capillary) and the capillary is checked for foreign matter and irregularity. The liquid is also checked for moisture. AFTER THIS INSPECTION THE THERMOMETER MUST RECOVER AT ROOM TEMPERATURE FOR A MINIMUM OF 72 HOURS.

Only after these 72 hours can the proper temperature testing be done. The instrument is tested in state-of-the-art baths against NIST traceable master standards at the test points specified either by standard or by our customer.

If the thermometer has an ice point that is calibrated, we will notify the end user after one year that the thermometer needs to have an ice point re-calibration (either in house or sent back to us). If the thermometer does not have an ice point calibration, the Report of Calibration will have an expiration date, and we will notify the end user that a complete re-calibration is due.