ASTM E1750-23 PDF

Overview

ASTM E1750-23: Standard Guide for Use of Water Triple Point Cells provides comprehensive guidance on the use of water triple-point cells as a reference temperature for the calibration of thermometers. The water triple point is a thermometric fixed point fundamental to defining the Kelvin Thermodynamic Temperature Scale (KTTS) and the International Temperature Scale of 1990 (ITS-90). This guide covers procedures for preparing and qualifying different types of commercially available water triple-point cells (Type A and B), maintaining their integrity, and employing them in precise temperature measurements.

Key Topics

• Nature and Configuration of Triple-Point Cells: The standard discusses the features of Type A and Type B water triple-point cells, which comprise high-purity sealed glass vessels filled with pure, air-free water.
• Realization of the Triple Point: Guidance on preparing the cell to establish the water triple-point by forming a uniform ice mantle, ensuring equilibrium between water’s solid, liquid, and vapor phases.
• Qualification Process: Details on qualifying a triple-point cell by comparison with a bank of similar cells of known history, as opposed to calibration.
• Reference Temperature: A qualified water triple-point cell is assigned the temperature 273.16 K on ITS-90, unless corrected for isotopic composition.
• Expanded Uncertainty: Specified procedures enable the realization of the triple-point temperature with expanded uncertainties ranging from ±0.05 mK to ±0.25 mK, depending on cell preparation and water isotopic composition.
• Integrity and Handling: Emphasizes maintaining the physical integrity of the cell, including tests for detecting air or soluble impurities and precautions to avoid breakage during handling.
• Measurement Procedures: Covers procedures for using Standard Platinum Resistance Thermometers (SPRTs) with the triple-point cell, including corrections for self-heating and hydrostatic head effects.

Applications

ASTM E1750-23 is crucial for laboratories, calibration service providers, and metrology institutes that require precise and reliable temperature calibration methods. Its primary applications include:

• Calibration of Thermometers: Used for calibrating high-precision thermometers, particularly standard platinum resistance thermometers (SPRTs), by providing a stable, intrinsic temperature reference.
• Temperature Scale Realization: Supports national and international metrology institutes in realizing and disseminating the ITS-90 temperature scale.
• Quality Assurance: Provides procedures to verify and maintain the integrity of reference cells, critical for sustained accuracy in temperature measurement and instrument calibration.
• Research and Development: Essential for scientific research that demands tight control and verification of temperature standards and ensuring traceability to the kelvin unit.

Related Standards

Several related ASTM and international standards provide complementary guidelines and terminology:

• ASTM E344 - Terminology Relating to Thermometry and Hydrometry: Provides key definitions used in temperature measurement.
• ASTM E1594 - Guide for Expression of Temperature: Offers guidance on expressing and reporting temperature measurements.
• ITS-90 (International Temperature Scale of 1990): The definitive scale for accurate temperature measurement, with the water triple point as a foundational reference point.
• ISO and BIPM Documentation: International references outlining the principles for temperature scale realization and the isotopic composition of reference water.

By adhering to ASTM E1750-23, organizations ensure the highest level of precision in temperature measurements, facilitate comparability across laboratories worldwide, and maintain compliance with internationally recognized measurement standards. This guide is an indispensable reference for anyone involved in precise thermometry and calibration activities.